Section 3 of this law has reference to colouring matter in food, drink

Transcriber's Note: Italic text is denoted by _underscores_ and bold

text by =equal signs=

FRONTISPIECE. PLATE I.

[Illustration: TEA PLANT.]

FOOD

ADULTERATION

AND

ITS DETECTION.

_WITH PHOTOMICROGRAPHIC PLATES AND

A BIBLIOGRAPHICAL APPENDIX._

BY

JESSE P. BATTERSHALL, Ph.D., F.C.S.,

CHEMIST, U.S. LABORATORY,

NEW YORK CITY.

[Illustration]

NEW YORK:

E. & F. N. SPON, 35, MURRAY STREET,

AND 125, STRAND, LONDON.

1887.

[_Copyright, 1887._ By JESSE P. BATTERSHALL.]

PREFACE.

To embody in a condensed form some salient features of the present

status of Food Adulteration in the United States is the object of this

volume. The importance of the subject, and the apparent need of a book

of moderate dimensions relating thereto, must suffice as its _raison

d’être_. The standard works have been freely consulted, and valuable

data have been obtained from the recent reports of our State and Civic

Boards of Health. The system of nomenclature accepted by the American

Chemical Society has been generally adopted. It was, however, deemed

advisable to retain such names as glycerine, sodium bicarbonate, etc.,

in place of the more modern but less well-known terms, glycerol and

sodium hydrogen carbonate, even at a slight sacrifice of uniformity.

The photogravure plates, most of which represent the results of recent

microscopical investigation, are considered an important feature of the

book. And it is believed that the bibliographical appendix, and the

collation of American Legislation on Adulteration, will supply a want

for ready reference often experienced.

U. S. LABORATORY,

_July 1st, 1887_.

CONTENTS.

PAGE

Introduction 1

Tea 12

Coffee 29

Cocoa and Chocolate 42

Milk 49

Butter 63

Cheese 83

Flour, Bread, and Starch 87

Bakers’ Chemicals 101

Sugar 104

Honey 121

Confectionery 129

Beer 132

Wine 157

Liquors 186

Water 200

Vinegar 225

Pickles 232

Olive Oil 233

Mustard 239

Pepper 243

Spices 249

Miscellaneous 254

Bibliography 258

Laws 268

Index 320

PLATES.

PAGE

I. Tea Plant _frontispiece_

II. Tea Leaves 17

III. Tea and other Leaves 18

IV. Cream and Cow’s Milk 61

V. Skimmed and Colostrum Milk 62

VI. Butter and Oleomargarine 78

VII. Fat Crystals 79

VIII. Artificial Digestion of

Butter and Oleomargarine 82

IX. Starches 100

X. Polariscope 112

XI. Organisms in Water 218

XII. Spices 252

FOOD ADULTERATION.

INTRODUCTION.

Of the various branches cognate to chemical research which excite

public attention, that of food adulteration doubtless possesses

the greatest interest. To the dealer in alimentary substances, the

significance of their sophistication is frequently merely one of profit

or loss, and even this comparatively unimportant consideration does

not always attach. But to the general community, the subject appeals

to interests more vital than a desire to avoid pecuniary damage, and

involving, as it necessarily does, the question of health, it has

engendered a feeling of uneasiness, accompanied by an earnest desire

for trustworthy information and data. The most usual excuses advanced

by dishonest traders, when a case of adulteration has been successfully

brought home to them--guilty knowledge being also established--are,

that they are compelled to resort to the misdeed by the public demand

for cheap commodities, that the addition is harmless, or actually

constitutes an improvement, as is asserted to be the case when

chicory is added to coffee, or that it serves as a preservative, as

was formerly alleged to be the fact when vinegar was fortified with

sulphuric acid. Pretexts of this sort are almost invariably fallacious.

The claim that manufacturers are often forced into adulteration by

the necessities of unfair trade competition possesses more weight--an

honest dealer cannot as a rule successfully compete with a dishonest

one--and has undoubtedly influenced many of the better class to

co-operate in attempts to prevent the practice. The general feeling

of uncertainty which exists in the public mind concerning the

actual extent and importance of food adulteration is probably to be

ascribed to two causes. In the first place, most of the literature

generally accessible relating to the subject has been limited to

sensational newspaper articles, reciting some startling instance

of food-poisoning, often unauthenticated and bearing upon its face

evidences of exaggeration. By reason of such publications, periodical

panics have been created in our large cities which, however, as a

rule quickly subside, and the community relapses into the customary

feeling of doubtful security, until aroused from its apathy by the next

_exposé_. The fact that the only reliable results of food investigation

have, until recently, been confined to purely scientific journals,

and therefore not prominently brought to public notice, is another

explanation of the lack of creditable information which generally

prevails concerning this species of sophistication.

The adulteration of alimentary substances was practised in the

civilised countries of Europe at a very remote date, and the early

history of the art, mainly collated by Prof. Blyth in his valuable

work on food,[1] is replete with interest. Bread certainly received

due attention at the hands of the ancient sophisticator. Pliny makes

several references to the adulteration of this food. In England,

as early as the reign of King John, the sale of the commodity was

controlled by the “Assize of Bread,” which, although originally

designed to regulate the price and size of the loaf, was subsequently

amplified so as to include penalties for falsification, usually

consisting of corporal punishment and exposure in the pillory. In

France, in 1382, ordinances were promulgated specifying the proper

mode of bread-making, the punishment for infringement being similar in

character to those inflicted in Great Britain. It is related that in

the year 1525, a guilty baker “was condemned by the court to be taken

from the Châtelet prison to the cross before the _Église des Carmes_,

and thence to the gate of _Notre Dame_ and to other public places in

Paris, in his shirt, having his head and feet bare, with small loaves

hung from his neck, and holding a large wax candle, lighted, and in

each of the places enumerated he was to make _amende honorable_, and

ask mercy and pardon of God, the king, and of justice for his fault.”

In Germany, during the fifteenth century, the bread adulterator,

while not subjected to a religious penance, did not escape from a

sufficiently practical rebuke, as it was the frequent custom to put him

in a basket attached to a long pole, and purge him of his misdeeds by

repeated immersions in a pool of water.

Wine would also appear to have been exposed to fraudulent admixture

in former times. Pliny mentions that in Rome considerable difficulty

was experienced, even by the wealthy, in securing the pure article,

and in Athens a public inspector was early appointed to prevent its

adulteration. In England, during the reign of Edward the Confessor,

punishment for brewing bad beer was publicly enforced, and, in

1529, official “ale tasters” flourished, without whose approval the

beverage was not to be sold. In later years, Addison, referring to the

manipulators of wine of his time, writes: “These subtle philosophers

are daily employed in the transmutation of liquors, and, by the power

of magical drugs and incantations, raise under the streets of London

the choicest products of the hills and valleys of France; they squeeze

Bordeaux out of the sloe and draw champagne from an apple.”[2] In the

fifteenth century, at Biebrich on the Rhine, a wine sophisticator was

forced to drink six quarts of his own stock, and it is recorded with

due gravity that the test resulted fatally. Not very many years since,

a manufacturer of wine at Rheims secured for his champagne, which was

chiefly consumed in Würtemberg, a high reputation, on account of the

unusually exhilarating effects following its use. Suspicion being at

length aroused, Liebig made a chemical examination of the article,

and found that it was at least unique in its gaseous composition,

being charged with one volume of carbonic acid gas and two volumes of

nitrous oxide, or “laughing gas.” These early attempts to control and

punish adulteration, while often possessing interest on account of

their quaintness, are chiefly important, as being the precursors of the

protective legal measures which exist in more modern times.

In 1802 the _Conseil de Salubrité_ was established in Paris, and this

body has since developed into numerous health boards, to whom the

French are at present mainly indebted for what immunity from food

falsification they enjoy. A very decided advance upon all preceding

methods to regulate the public supply of food was signalised in 1874

by the organisation in England of the Society of Public Analysts, who

formulated a legal definition of adulteration, and issued the standards

of purity which articles of general consumption should meet. This

society was supported in its valuable services by the enactment, in

1875, of the Sale of Food and Drugs Act, which, with the amendment

added in 1879, seems to embrace all necessary safeguards against

the offences sought to be suppressed. The results of their work are

tabulated as follows:--

---------+-----------+--------------+----------------

Year. | Samples | Samples | Percentage

| Examined. | Adulterated. | of Adulterated.

---------+-----------+--------------+----------------

1875-6 | 15,989 | 2,895 | 18·10

1877 | 11,943 | 2,371 | 17·70

1878 | 15,107 | 2,505 | 16·58

1879 | 17,574 | 3,032 | 17·25

1880 | 17,919 | 3,132 | 17·47

---------+-----------+--------------+----------------

Of the total number of samples tested, the classification of

adulterations is as below:--

Per cent.

Milk 50·98

Butter 5·73

Groceries 12·90

Drugs 2·52

Wine, spirits, and beer 15·18

Bread and flour 2·68

Waters (including mineral) 9·18

Sundries 0·83

More recent data concerning the falsification of food in Great Britain

are as follows:--

---------+---------+--------------+-------------

Year. | Samples | Number | Per cent. of

| Tested. | Adulterated. | Adulterated.

---------+---------+--------------+-------------

1881 | 17,823 | 2,495 | 14·0

1882 | 19,439 | 2,916 | 15·0

1883 | 14,900 | 2,453 | 16·4

---------+---------+--------------+-------------

Of the samples of spirits and beer examined, about 25 per cent. were

adulterated.

The results of the work done at the Paris Municipal Laboratory are the

following:--

--------+---------+-------+-----------+------------------------

| | | | Bad.

| | | +------------+-----------

Year. | Samples | Good. | Passable. | Not |

| Tested. | | | Injurious. | Injurious.

--------+---------+-------+-----------+------------+-----------

1881 | 6,258 | 1,565 | 1,523 | 2,608 | 562

1882 | 10,752 | 2,707 | 2,679 | 3,822 | 1,544

1883 | 14,686 | -- | -- | -- | --

--------+---------+-------+-----------+------------+-----------

The American characteristic of controlling their own personal affairs,

and the resulting disinclination to resort to anything savouring of

parental governmental interference, has probably had its effect in

retarding early systematic action in the matter of adulteration.

Sporadic attempts to secure legislative restrictions have, it is true,

occasionally been made, but the laws passed were almost invariably of a

specific nature, designed to meet some isolated case, and were destined

to share the fate of most legislation of the kind--the particular

adulteration being for the nonce suppressed, the law became practically

a dead letter. Subsequent effort to obtain more comprehensive laws

inclined to the other extreme, and the enactments secured were so

general in scope, and so deficient in details, that loopholes were

inadvertently allowed to remain, through which the crafty adulterator

often managed to escape.

The present food legislation in the United States was to some extent

anticipated in 1848 by an Act of Congress to secure the purity of

imported drugs. In this enactment these are directed to be tested

by the standards established by the various official pharmacopœias;

twenty-three are specifically enumerated, the most important being

Peruvian bark and opium. The Act is still in force. All previous

efforts to regulate the quality of our food supply culminated in

1877 in formal action being taken by several of the State Boards of

Health, at whose instance laws against adulteration were formulated,

and chemists commissioned to collect and examine samples of alimentary

substances, and furnish reports on the subject. These may be found in

the publications of the same, notably in the volumes issued by the

New York, Massachusetts, Michigan, and New Jersey Boards. The service

rendered to the public by these investigations is almost incalculable,

and the annual reports containing the results of the same are fraught

with interest. For the first time we are placed in possession of

trustworthy statistics, indicating the extent of food sophistication in

this country.

The annual report of the New York City Board of Health for the year

1885 furnishes the following statistics:--

Milk examined 7,006 samples.

Adulterated milk destroyed 1,701 quarts.

Candy destroyed 72,700 lbs.

Cheese „ 5,700 „

Packages of tea, ordered out of sale 266

Canned goods condemned 39,905 „

Pickles „ „ 4,000

Coffee „ „ 4,100 „

Pepper, spices, and baking powder 1,455 „

Meat and fish 790,410 „

Fruit 212,000 „

Total inspections 43,665

Complaints made 5,786

Fines collected $2,070

Some of the results of the work performed by the New York State Board

of Health during the year 1882 are tabulated below:--

----------------+-----------+--------------+--------------

| Number of | Number | Per cent. of

Article. | Samples | found to be | Adulterated.

| Tested. | Adulterated. |

----------------+-----------+--------------+--------------

Butter | 40 | 21 | 52·50

Olive oil | 16 | 9 | 56·25

Baking powder | 84 | 8 | 9·52

Flour | 117 | 8 | 6·84

Spices | 180 | 112 | 62·22

Coffee (ground) | 21 | 19 | 90·48

Candy (yellow) | 10 | 7 | 70·00

Brandy | 25 | 16 | 64·00

Sugar (brown) | 67 | 4 | 5·97

----------------+-----------+--------------+--------------

In interpreting the significance of the foregoing table, it should be

borne in mind that in the vast majority of cases the adulterations

practised were not of an injurious nature, but consisted of a

fraudulent admixture of some cheaper substance, the object being an

increase of bulk or weight resulting in augmented profit.

Much of the embarrassment experienced by health authorities in their

efforts to bring persons guilty of food adulteration to punishment is

due to the lack of explicit detail in the law. It is far easier to

substantiate the fact of the adulteration than it is to produce the

offender in court and secure his conviction. Numerous cases are on

record illustrating the peculiar contingencies which at times arise.

Probably with the best intention, a milk vendor labelled his wagon,

“Country skimmed milk, sold as adulterated;” an inspector bought a

sample, not noticing the label, and the magistrate convicted the

vendor, doubtless on the ground that due attention had not been

directed to the advertisement.[3] Chief Justice Cockburn, in referring

to an analogous case, said: “If the seller chooses to sell an article

with a certain admixture, the onus lies on him to prove that the

purchaser knew what he was purchasing.” In most instances, when in

ostensible compliance with the law, a package bears a label purporting

to state the actual nature of its contents, the label is either printed

in such small type, or is placed in so inconspicuous a position, that

the buyer is in ignorance of its existence at the time the purchase is

made. A confectioner in Boston was suspected of selling adulterated

candy, and while it was proved that a sample bought of him contained

a dangerous proportion of a poisonous pigment--chromate of lead--he

escaped conviction, on the plea that candy was not an article of food

within the meaning of the existing law, which, it seems, has since been

amended so as to embrace cases of this kind.

In a recent action brought by the New York Board of Health to obtain an

injunction against the sale of certain Ping Suey teas, it was held by

the court, in refusing to grant the same, that, although the teas in

question had been clearly shown to be adulterated with gypsum, Prussian

blue, sand, etc., it was likewise necessary to prove that the effect of

these admixtures was such as to constitute a serious danger to public

health.

As a result of the publicity lately given to the subject of food

adulteration, a popular impression has been produced that any substance

employed as an adulterant of, or a substitute for another, is to be

avoided _per se_. Perhaps the common belief that for all purposes

cotton-seed oil is inferior to olive oil, and oleomargarine to butter,

is the most striking illustration of this tendency. Now, as a matter

of fact, pure cotton-seed oil, as at present found on the market,

is less liable to become rancid than the product of the olive, and,

for many culinary uses, it is at least quite as serviceable. Absolute

cleanliness is a _sine qua non_ in the successful manufacture of

oleomargarine, and, as an economical substitute for the inferior kinds

of butter often exposed for sale, its discovery cannot justly be

regarded a misfortune. The sale of these products, _under their true

name_, should not only be allowed, but under some circumstances even

encouraged.

The benefits accruing to the community by reason of the service of our

State Boards of Health are so evident and so important, that it is

almost incredible that these bodies have not been put in possession

of all the facilities necessary for their work. It would appear,

however, that, while our legislators have been induced to enact good

laws regulating adulteration, they have often signally failed to fulfil

all the requirements indispensable to the efficient execution of the

same. Without entering into the details of this branch of the subject,

it is proper to observe that owing to the lack of necessary funds,

great pecuniary embarrassment has been experienced in securing the

services of a competent corps of experts, who, in addition to their

inadequate remuneration, must incur the expenses of purchasing samples.

The appointment of public analysts in our larger towns and cities--as

has for some time been the case in Great Britain--is certainly to be

urgently recommended.

All attempts to awaken public interest in the subject of food

adulteration are of any real service only as they may be conducive to

the adoption of more advanced and improved measures for the suppression

of the practice.

In general, the adulterations to which food is subjected may be divided

into those positively deleterious to health (such as the colouring of

confectionery by chrome yellow), those which are only fraudulent (such

as the addition of flour to mustard), and those which may be fairly

considered as accidental (such as the presence of a small amount of

sand in tea). It would exceed the limits of this volume to enter into a

comprehensive review of the almost endless varieties of adulteration.

The following list embraces the articles most exposed to falsification,

together with the adulterants commonly employed:--

Article. Common Adulterants.

Baker’s chemicals Starch, alum.

Bread and flour Other meals, alum.

Butter Water, colouring matter, oleomargarine, and

other fats.

Canned foods Metallic poisons.

Cheese Lard, oleomargarine, cotton-seed oil, metallic

salts (in rind).

Cocoa and chocolate Sugar, starch, flour.

Coffee Chicory, peas, rye, corn, colouring matters.

Confectionery Starch-sugar, starch, artificial essences,

poisonous pigments, terra alba, plaster of

Paris.

Honey Glucose-syrup, cane sugar.

Malt liquors Artificial glucose and bitters, sodium

bicarbonate, salt.

Milk Water, and removal of cream.

Mustard Flour, turmeric, cayenne.

Olive oil Cotton-seed and other oils.

Pepper Various ground meals.

Pickles Salts of copper.

Spices Pepper-dust, starch, flour.

Spirits Water, fusil oil, aromatic ethers, burnt

sugar.

Sugar Starch-sugar.

Tea Exhausted tea leaves, foreign leaves, indigo,

Prussian blue, gypsum, soap-stone, sand.

Vinegar Water, sulphuric acid.

Wine Water, spirits, coal tar and vegetable

colours, factitious imitations.

The above table includes those admixtures which have actually been

detected by chemists of repute within the past few years, and omits

many rather sensational forms of adulteration mentioned in the early

treatises on the subject, the practice of which appears to have been

discontinued.

In the following pages, some of the more important articles of food

and drink are described with especial reference to their chemical

relations and the ordinary adulterations to which they are exposed.

It should be added, that many of the methods of examination given

are quoted in a condensed form from the more extensive works on

food-analysis.

FOOTNOTES:

[1] ‘Foods: Composition and Analysis,’ pp. 1-18.

[2] _The Tatler_, 1710.

[3] ‘Analyst,’ 1880, p. 225.

TEA.

The early history of tea is probably contemporary with that of China,

although, in that country, the first authentic mention of the plant

was as late as A.D. 350; while, in European literature, its earliest

notice occurs in the year 1550. The first important consignment of

tea into England took place in 1657. Chinese tea made its appearance

in the United States in 1711; in 1858, the importation of Japan tea

began. During the season of 1883-1884, the importation of tea into

this country[4] was--from China, 30½ millions of pounds; from Japan,

32½ millions of pounds. Recently, numerous shipments of Indian tea

have been placed upon our markets, the quality of which compares very

favourably with the older and better known varieties. During the past

four years the consumption of tea in this country has materially

decreased; whilst that of coffee has undergone an almost corresponding

increase. The _per capita_ consumption of tea and coffee in the United

States as compared with that of Great Britain is as follows:--United

States, tea, 1·16; coffee, 9·50; Great Britain, tea, 4·62; coffee,

0·89. In the year 1885 our importation of tea approximated 82 millions

of pounds, that of coffee being nearly 455 millions of pounds.

Genuine tea is the prepared leaf of _Thea sinensis_. The growth of the

tea shrub is usually restricted by artificial means to a height of from

three to five feet. It is ready for picking at the end of the third

year, the average life of the plant being about ten years. The first

picking is made in the middle of April, the second on the 1st of May,

the third in the middle of July, and occasionally a fourth during the

month of August. The first pickings, which obviously consist of the

young and more tender leaves, furnish the finer grades of tea. After

sorting, the natural moisture of the leaves is partially removed by

pressing and rolling; they are next more thoroughly dried by gently

roasting in iron pans for a few minutes. The leaves are then rolled on

bamboo tables and again roasted, occasionally re-rolled and re-fired,

and finally separated into the various kinds, such as twankay, hyson,

young hyson, gunpowder, etc., by passing through sieves. The difference

between green and black tea is mainly due to the fact that the former

is dried shortly after gathering, and then rolled and carefully fired,

whereas black tea is first made up into heaps, which are exposed to the

air for some time before firing and allowed to undergo a species of

fermentation, resulting in the conversion of its original olive-green

into a black colour. The methods employed in the preparation of the tea

are somewhat modified in their details in the different tea districts

of China and Japan. In Japan two varieties of the leaf are used, which

are termed “otoko” (male), and “ona” (female), the former being larger

and coarser than the latter. After picking, the leaves are steamed by

placing them in a wooden tray suspended over boiling water, in which

they are allowed to remain for about half a minute. They are next

thrown upon a tough paper membrane attached to the top of an oven,

which is heated by burning charcoal covered with ashes, where they are

constantly manipulated by the hand until the light-green colour turns

to a dark olive, and the leaves have become spirally twisted. After

this “firing,” the tea is dried at a low temperature for from four

to eight hours; it is next sorted by passing through sieves, and is

then turned over to the “go-downs,” or warehouses of the foreigners,

where the facing process is carried on by placing the tea in large

metallic bowls, heated by means of a furnace, and gradually adding the

various pigments used, the mixture being continually stirred. The tea

is finally again sorted by means of large fans, and is now ready for

packing and shipment.

The sophistications to which tea is exposed have received the careful

attention of chemists, but not to a greater extent than the importance

of the subject merits; indeed, it is safe to assert that no article

among alimentary substances has been, at least in past years, more

subjected to adulteration. The falsifications which are practised to no

inconsiderable extent may be conveniently divided into three classes.

1st. Additions made for the purpose of giving increased weight and

bulk, which include foreign leaves and spent tea leaves, and also

certain mineral substances, such as metallic iron, sand, brick-dust,

etc.

2nd. Substances added in order to produce an artificial appearance of

strength to the tea decoction, catechu and other bodies rich in tannin

being mainly resorted to for this purpose.

3rd. The imparting of a bright and shining appearance to an inferior

tea by means of various colouring mixtures or “facings,” which

operation, while sometimes practised upon black tea, is far more

common with the green variety. This adulteration involves the use

of soap-stone, gypsum, China clay, Prussian blue, indigo, turmeric,

and graphite. The author lately received from Japan several samples

of the preparations employed for facing the tea in that country,

the composition of which was shown by analysis to be essentially as

follows:--

1. Magnesium silicate (soap-stone).

2. Calcium sulphate (gypsum).

3. Turmeric.

4. Indigo.

5. Ferric ferrocyanide (Prussian blue).

6. Soap-stone, 47·5 per cent.; gypsum, 47·5 per cent.; Prussian blue, 5

per cent.

7. Soap-stone, 45 per cent.; gypsum, 45 per cent.; Prussian blue, 10

per cent.

8. Soap-stone, 75 per cent.; indigo, 25 per cent.

9. Soap-stone, 60 per cent.; indigo, 40 per cent.

The “facing” or “blooming” of tea is often accomplished by simply

placing it in an iron pan, heated by a fire, and rapidly incorporating

with it one of the preceding mixtures (Nos. 6, 7, 8, or 9), in the

proportion of about half a dram to seven or eight pounds of the tea, a

brisk stirring being maintained until the desired shade of colour is

produced.

Some of the above forms of sophistication usually go together;--thus

exhausted tea is restored by facing. The collection of the spent leaves

takes place in China. Much of the facing was, until about three years

since, done in New York city, and constituted a regular branch of

business, which included among its operations such metamorphoses as the

conversion of a green tea into a black, and _vice versâ_.

According to James Bell,[5] the composition of genuine tea is as

follows:--

----------------------------+-----------+-------------

| Congou. | Young Hyson.

----------------------------+-----------+-------------

| per cent. | per cent.

Moisture | 8·20 | 5·96

Theine | 3·24 | 2·33

Albumin, insoluble | 17·20 | 16·83

„ soluble | 0·70 | 0·80

Extractive, by alcohol | 6·79 | 7·05

Dextrine, or gum | .. | 0·50

Pectin and pectic acid | 2·60 | 3·22

Tannin | 16·40 | 27·14

Chlorophyll and resin | 4·60 | 4·20

Cellulose | 34·00 | 25·90

Ash | 6·27 | 6·07

+-----------+-------------

| 100·00 | 100·00

----------------------------+-----------+-------------

The ash of samples of uncoloured and unfaced tea, and of spent tea

analysed by the author, had the following composition:--

-----------------------+------------+-----------+-----------

| Oolong | |

|(average of | Japan. |Spent Black

|50 samples).| | Tea.

-----------------------+------------+-----------+-----------

| per cent. | per cent. | per cent.

Total ash | 6·04 | 5·58 | 2·52

Soluble in water | 3·44 | 3·60 | 0·28

Per cent. soluble | 57·00 | 64·55 | 11·11

-----------------------+------------+-----------+-----------

_Composition._

Silica | 11·30 | 9·30 | 27·75

Chlorine | 1·53 | 1·60 | 0·79

Potassa | 37·46 | 41·63 |

Soda | 1·40 | 1·12 |

Ferric oxide | 1·80 | 1·12 } | 16·00

Alumina | 5·13 | 4·26 } |

Manganic oxide | 2·10 | 1·30 |

Lime | 9·43 | 8·18 | 19·66

Magnesia | 8·00 | 5·33 | 11·20

Phosphoric acid | 12·27 | 16·62 | 15·80

Sulphuric acid | 4·18 | 3·64 | 1·10

Carbonic acid | 5·40 | 5·90 | 6·70

+-----------+-----------+----------

| 100·00 | 100·00 | 99·00

-----------------------+-----------+-----------+----------

“Tea dust” affords a high proportion of ash, sometimes amounting to 20

per cent., the composition of which is usually strikingly different

from that of the ash of ordinary tea. It is deficient in potassa and

phosphoric acid, and the amount of ash insoluble in water and acids

is very excessive, as is shown by the following analysis, made by the

author:--

_Ash of Tea Dust._

Per cent.

Insoluble in acids 60·30

Alumina and ferric oxide 6·60

Lime 5·10

Magnesia 7·89

Potassa 11·00

Soda 2·51

Sulphuric acid 1·23

Chlorine 0·63

Phosphoric acid 4·73

-----

99·99

Ash insoluble in water 80·00

PLATE II.

[Illustration: TEA LEAVES.]

The portion of ash insoluble in acids consisted of silica, clay, and

soapstone, indicating that the ash of tea dust is largely composed of

the mineral substances employed for “facing” purposes.

The characteristics of the ash of unspent tea are the presence of

manganic oxide, the large proportion of potassium salts present, and

the solubility of the ash in water. The amount of ash in genuine

tea ranges from five to six per cent. In the absence of exhausted

leaves, it has been found that the finer sorts of tea afford a smaller

proportion of ash than the inferior grades. It will be noticed that

spent tea ash exhibits a marked increase in the proportion of insoluble

compounds (silica, alumina, and ferric oxide), as well as a total

absence of potassium salts.

The presence of foreign leaves, and, in some instances, of mineral

adulterants in tea is best detected by means of a microscopical

examination of the suspected sample. The genuine tea-leaf is

characterised by its peculiar serrations and venations. Its border

exhibits serrations which stop a little short of the stalk, while the

venations extend from the central rib, nearly parallel to one another,

but turn just before reaching the border of the leaf.

Plate I. (Frontispiece) is a photogravure of a twig of the tea plant,

in possession of the author. The leaves are of natural size, but the

majority are of a greater maturity than those used in the preparation

of tea, which more resemble in size the few upper leaves.

Plate II. shows more distinctly the serrations and venations of the

tea-leaf. The Chinese are said to occasionally employ ash, camelia,

and dog-rose leaves for admixture with tea, and the product is stated

to have formerly been subjected in England to the addition of sloe,

willow, beech, hawthorn, oak, etc. For scenting purposes, chulan

flowers, rose, jasmine, and orange leaves, have been employed. The

writer has lately received from Japan specimens of willow, wisteria,

_te-mo-ki_, and other leaves which at one time were used in that

country as admixtures.

Plate III. exhibits some of these leaves, two genuine Japan tea-leaves

being included for purpose of comparison. The leaves represented in

this plate are: 1, beech; 2, hawthorn; 3, rose; 4, Japan tea; 5,

willow; 6, _te-mo-ki_; 7, elm; 8, wisteria; 9, poplar. From very recent

reports of the American consuls in Japan and China, it would appear

that the addition of foreign leaves to tea is at present but seldom

resorted to, and this accords with the author’s experience in the

testing of the teas imported into this country.

In 1884, the Japanese Government made it a criminal offence to

adulterate tea, and instituted “tea guilds,” which are governed by

very stringent laws, and of which most dealers of repute are members.

The facing of tea does not appear, however, to have been considered an

adulteration, its continued practice being justified by the plea that

otherwise Japan teas would not suit the taste of American consumers.

PLATE III.

[Illustration: TEA AND OTHER LEAVES.]

In the microscopic examination of tea, the sample should be moistened

with hot water and spread out on a glass plate, and then submitted to

a careful inspection, especial attention being directed to the general

outline of the leaf and its serrations and venations. The presence

of exhausted tea-leaves may often be detected by their soft texture

and generally disintegrated appearance. If a considerable quantity

of the tea be placed in a long glass cylinder and agitated with cold

water, the colouring and other abnormal substances frequently become

detached, and either rise to the surface of the liquid as a sort of

scum, or fall to the bottom as a sediment. In this way Prussian blue,

indigo, soapstone, gypsum, sand, and turmeric can often be separated,

and subsequently recognised by their characteristic appearance under

the microscope. The separated substances should also be subjected

to a chemical examination. Prussian blue is detected by heating

with a solution of sodium hydroxide, filtering, acidulating the

filtrate with acetic acid, and then adding ferric chloride, when,

in its presence, a blue colour will be produced. Indigo is best

recognised by the microscopic examination. It is not decolorised by

caustic alkali, but it dissolves in sulphuric acid to a blue liquid.

Soapstone, gypsum, sand, and metallic iron, are identified by means of

the usual chemical reactions. A compound very aptly termed “Lie-tea,”

is sometimes met with. It forms little pellets, consisting of tea-dust

mixed with foreign leaves, sand, etc., and held together by means of

gum or starch. This falls to powder if treated with boiling water.

In the presence of catechu, the tea infusion usually assumes a muddy

appearance upon standing. In case iron salts have been employed to

deepen the colour of the infusion, they can be detected by treating the

ground tea-leaves with acetic acid, and testing the filtered solution

with potassium ferrocyanide. Tea should not turn black upon immersion

in hydrosulphuric acid water, nor should it impart a blue colour to

ammonia water. The infusion should be amber-coloured, and not become

reddened by the addition of an acid.

The United States Tea Adulteration Act was passed by Congress in 1883.

The enactment of this law was largely due to the exertions of prominent

tea merchants, whose business interests were seriously affected by

the sale (principally in trade auctions) of the debased or spurious

article. It is stated in the official report of the United States Tea

Examiner at New York City, that from March 1883 to December of the same

year, 856,281 packages (about four millions of pounds) of tea were

inspected, of which 7000 packages (325,000 pounds) were rejected as

unfit for consumption. Since the enforcement in New York City of the

Tea Adulteration Act, nearly 2000 samples of tea have been chemically

tested under the direction of the author. The proportion grossly

adulterated has been a little over nine per cent. But this does not

apply to the total amount imported, since only those samples which were

somewhat suspicious in appearance were submitted for analysis. As the

result of the past two years’ experience in the chemical examination of

tea, the prevailing adulterations were found to be of two kinds--the

admixture of spent tea-leaves, and the application to the tea of a

facing preparation. A natural green tea possesses a dull hue, and is

but seldom met with in the trade; some Moyunes and uncoloured Japans

(which latter, properly speaking, is not a green tea) being almost

the only varieties not exhibiting the bright metallic lustre due to

the facing process. The addition of foreign leaves was detected only

in a few instances; the presence of sand and gravel occurred far more

frequently. Apropos of the practical utility of Governmental sanitary

legislation, it can be stated that, since the enforcement of the

Adulteration Act, the tea imported into the city of New York has very

perceptibly improved in quality.

Attempts in tea culture are being made in the United States of

Columbia, S.A. A specimen of the prepared plant received by the writer,

differed greatly in appearance from the Chinese and Japanese products.

The leaves, which had not been rolled but were quite flat, possessed

a light pea-green colour and a fine but rather faint aroma. An

examination indicated that the tea, although very delicate in quality,

was seriously deficient in body.

The analysis showed:--

Per cent.

Moisture 6·70

Total ash 4·82

Ash soluble in water 1·62

Ash insoluble in water 3·20

Ash insoluble in acid 0·16

Extract 27·40

Tannic acid 4·31

Theine 0·66

Insoluble leaf 65·90

The following Tea Assay, while not including the determinations of all

the proximate constituents of the plant, will, it is believed, in most

instances suffice to indicate to the analyst the presence of spent

leaves, mineral colouring matters, and other inorganic adulterations.

_Theine_ (_Caffeine_), C_{8}H_{10}N_{4}O_{2}.--Contrary to the once

general belief, there does not always exist a direct relation between

the quality of tea (at least so far as this is indicated by its

market price) and the proportion of theine contained, although the

physiological value of the plant is doubtless due to the presence of

this alkaloid.

The commercial tea-taster is almost entirely guided in his judgment in

regard to the value of a sample of tea by the age of the leaf, and by

the flavour or bouquet produced upon “drawing,” and this latter quality

is to be mainly ascribed to the volatile oil.

The following process will serve for the estimation of theine:--A

weighed quantity of the tea is boiled with distilled water until

the filtered infusion ceases to exhibit any colour. The filtrate is

evaporated on a water bath to the consistence of a syrup; it is next

mixed with calcined magnesia to alkaline reaction, and carefully

evaporated to dryness.

The residue obtained is then finely powdered, digested for a day or

so with ether (or chloroform) and filtered, the remaining undissolved

matter being again digested with a fresh quantity of ether, so long as

any further solution of theine takes place. The ether is now removed

from the united filtrates by distillation, whereupon the theine will be

obtained in a fairly pure condition.

Theine contains a very large proportion of nitrogen (almost 29 per

cent.), and Wanklyn[6] has suggested the application of his ammonia

process (see p. 205) to the analysis of tea. Genuine tea is stated to

yield from 0·7 to 0·8 per cent. of total ammonia, when tested in this

manner.

_Volatile Oil._--Ten grammes of the tea are distilled with water; the

distillate is filtered, saturated with calcium chloride, then well

agitated with ether, and allowed to remain at rest for some time.

The ethereal solution is subsequently drawn off, and spontaneously

evaporated in a weighed capsule. The increase in weight gives

approximately the amount of oil present. A sample of good black tea

yielded by this method 0·87 per cent. of volatile oil.

_Tannin._--Two grammes of the well-averaged sample are boiled with

100 c.c. of water, for about an hour, and the infusion filtered, the

undissolved matter remaining upon the filter being thoroughly washed

with hot water, and the washings added to the solution first obtained.

If necessary, the liquid is next reduced to a volume of 100 c.c. by

evaporation over a water-bath. It is then heated to boiling, and 25

c.c. of a solution of cupric acetate added. The copper solution is

prepared by dissolving five grammes of the salt in 100 c.c. of water,

and filtering. The precipitate formed is separated by filtration,

well washed, dried, and ignited in a porcelain crucible. A little

nitric acid is then added and the ignition repeated. One gramme of the

cupric oxide thus obtained represents 1·305 grammes of tannin. For

the estimation of spent leaves (especially in black tea), Mr. Allen

suggests the following formula, in which E represents the percentage of

spent tea, and T the percentage of tannin found:--

E = ((10 - T)100) / 8.

_The Ash._--_a. Total Ash._--Five grammes of the sample are placed

in a platinum dish and ignited over a Bunsen burner until complete

incineration is accomplished. The vessel is allowed to cool in a

desiccator, and is then quickly weighed. In genuine tea the total ash

should not be much below 5 per cent., nor much above 6 per cent., and

it should not be magnetic. In faced teas the proportion of total ash is

sometimes 10 per cent.; in “lie-tea” it may reach 30 per cent.; while

in spent tea it frequently falls below 3 per cent., the ash in this

case being abnormally rich in lime salts, and poor in potassium salts.

_b. Ash insoluble in water._--The total ash obtained in _a_ is washed

into a beaker, and boiled with water for a considerable time. It is

then brought upon a filter, washed, dried, ignited, and weighed. In

unadulterated tea it rarely exceeds 3 per cent. of the sample taken.

_c. Ash soluble in water._--This proportion is obtained by deducting

the ash insoluble in water from the total ash. Genuine tea contains

from 3 per cent. to 3·5 per cent. of soluble ash, or at least 50 per

cent. of the total ash, whereas in exhausted tea the amount is often

but 0·5 per cent. The following formula has been proposed for the

calculation of the percentage of spent tea E, where S is the percentage

of soluble ash obtained:--

E = (6 - 2S)20.

A sample prepared by averaging several good grades of black tea, was

mixed with an equal quantity of exhausted tea-leaves. The proportion

of soluble ash in the mixture was found to be 1·8 per cent. According

to the above formula, the spent tea present would be 48 per cent., or

within 2 per cent. of the actual amount.

_d. Ash insoluble in acid._--The ash insoluble in water is boiled with

dilute hydrochloric acid, and the residue separated by filtration,

washed, ignited, and weighed. In pure tea, the remaining ash ranges

between 0·3 and 0·8 per cent.; in faced tea, or in tea adulterated by

the addition of sand, etc., it may reach the proportion of 2 to 5 per

cent. Fragments of silica and brickdust are occasionally found in the

ash insoluble in acid.

_The Extract._--Two grammes of the _carefully sampled_ tea are

boiled with water until all soluble matter is dissolved, more water

being added from time to time to prevent the solution becoming too

concentrated. The operation may also be conducted in a flask connected

with an ascending Liebig’s condenser. In either case, the infusion

obtained is poured upon a tared filter, and the remaining insoluble

leaf repeatedly washed with hot water so long as the filtered liquor

shows a colour. The filtrate is now diluted to a volume of 200 c.c.,

and of this 50 c.c. are taken and evaporated in a weighed dish until

the weight of the extract remains constant. Genuine tea affords from 32

to 50 per cent. of extract, according to its age and quality; in spent

tea the proportion of extract will naturally be greatly reduced. Mr.

Allen employs the formula below for determining the percentage of spent

tea E in a sample, R representing the percentage of extract found.

E = ((32 - R)100) / 30.

In order to test the practical value of this equation, a sample of

black tea was mixed with 50 per cent. of spent tea-leaves, and a

determination made of the extract afforded. The calculated proportion

of spent tea was 44 per cent., instead of 50 per cent. It should be

added, however, that the tea taken subsequently proved to be of a very

superior quality, yielding an extract of 40 per cent.

_Gum (Dextrine)._--The proportion of gum contained in genuine tea is

usually inconsiderable. Its separation is effected by treating the

concentrated extract with alcohol, allowing the mixture to stand at

rest for a few hours, and collecting the precipitated gum upon a tared

filter, and carefully drying and weighing it. As a certain amount of

mineral matter is generally present in the precipitate, this should

afterwards be incinerated and a deduction made for the ash thus

obtained. A more satisfactory method is to treat the separated dextrine

with very dilute sulphuric acid, and estimate the amount of glucose

formed by means of Fehling’s solution (see p. 37); 100 parts of glucose

are equivalent to 90 parts of dextrine.

_Insoluble Leaf._--The insoluble leaf as obtained in the determination

of the extract, together with the weighed filter, is placed in an

air-bath, and dried for at least eight hours at a temperature of

100°,[7] and then weighed. In genuine tea the amount of insoluble

leaf ranges from 47 to 54 per cent.; in exhausted tea it may reach a

proportion of 75 per cent. or more. It should be noted that in the

foregoing estimations the tea is taken in its ordinary air-dried

condition. If it be desired to reduce the results obtained to a dry

basis, an allowance for the moisture present in the sample (an average

of 6 to 8 per cent.), or a direct determination of the same must be

made.

The following tabulation gives the constituents of genuine tea, so far

as the ash, extract, and insoluble leaf are involved:--

_Total ash_ ranges between 4·7 and 6·2 per cent.

_Ash soluble in water_ ranges between 3 and 3·5 per cent.; should equal

50 per cent. of total ash.

_Ash insoluble in water_, not over 3 per cent.

_Ash insoluble in acid_ ranges between 0·3 and 0·8 per cent.

_Extract_[8] ranges between 32 and 50 per cent.

_Insoluble leaf_ ranges between 43 and 58 per cent.

The table below may prove useful as indicating the requirements to be

exacted when the chemist is asked to give an opinion concerning the

presence of facing admixtures, or of exhausted or foreign leaves in a

sample of tea.

_Total ash_ should not be under 4·5 per cent. or above 7 per cent.

_Ash soluble in water_ should not be under 40 per cent. of total ash.

_Ash insoluble in water_ should not be over 3·25 per cent.

_Ash insoluble in acid_ should not be over 1 per cent.

_Extract_ (excepting in poor varieties of Congou tea) should not be

under 30 per cent.

_Insoluble Leaf_ should not be over 60 per cent.

The British Society of Public Analysts adopt:--

_Total ash_ (dry basis), not over 8 per cent. (at least 3 per cent.

should be soluble in water).

_Extract_ (tea as sold), not under 30 per cent.

Below are the proportions of total ash, ash soluble in water, and

extract found in 850 samples of tea (mostly inferior and faced),

examined under the direction of the author in the U.S. Laboratory:--

TOTAL ASH.

---------+--------+--------+--------+--------+-------+--------

Range |5 to 5½ |5½ to 6 |6 to 6½ |6½ to 7 |7 to 8 |8 p.c.

| p.c. | p.c. | p.c. | p.c. | p.c. |and over

Number | 21 | 76 | 102 | 194 | 421 | 36

Per cent.| 2·47 | 8·94 | 12·00 | 21·64 | 49·53 | 4·23

---------+--------+--------+--------+--------+-------+--------

ASH SOLUBLE IN WATER.

---------+---------+----------+--------------+---------------

Range | Under 2 |2 to 3 per|3 to 3½ per |3½ per cent.

|per cent.| cent. | cent. | and over.

Number | 25 | 649 | 157 | 19

Per cent.| 2·94 | 76·35 | 18·70 | 2·23

---------+---------+----------+--------------+---------------

EXTRACT.

---------+---------+------------+------------+-------------

Range |20 to 25 |25 to 30 per|30 to 35 per|35 to 40 per

|per cent.| cent. | cent. | cent.

Number | 21 | 151 | 499 | 179

Per cent.| 2·47 | 17·76 | 58·70 | 21·05

---------+---------+------------+------------+-------------

The following tabulation exhibits the results obtained by the

examination of various grades of Formosa, Congou, Young Hyson,

Gunpowder, and Japan tea, made, under the supervision of the writer, by

Dr. J. F. Davis.

It will be noticed, if the same varieties of tea be compared, that,

with some exceptions, their commercial value is directly proportional

to the percentages of soluble ash, extract, tannin, and theine

contained.

--------------+------------------------------------------------------

|Formosa Oolong, Choice, 1st Crop.

| +------------------------------------------------

| | Formosa Oolong, Superior, 1st Crop.

| | +------------------------------------------

| | |Formosa Oolong, Choice, 3rd Crop.

| | | +------------------------------------

Variety. | | | |Formosa Oolong, Superior, 3rd Crop.

| | | | +------------------------------

| | | | |Congou, Choicest.

| | | | | +---------------------

| | | | | |Congou, Medium.

| | | | | | +---------------

| | | | | | |Congou, Common.

--------------+-----+-----+-----+-----+--------+-----+---------------

| c. | c. | c. | c. | c. | c. | c.

Price per lb. | 70 | 28 | 55 | 24 |65 to 70| 24 | 14

(wholesale).| | | | | | |

|p.c. |p.c. |p.c. |p.c. | p.c. |p.c. |p.c.

Total ash | 6·50| 5·96| 5·80| 6·34| 6·22 | 6·36| 6·58

Ash soluble in| 3·60| 2·86| 3·12| 3·60| 3·56 | 3·00| 2·88

water. | | | | | | |

Ash insoluble | 2·90| 3·10| 2·68| 2·74| 2·66 | 3·36| 3·70

in water. | | | | | | |

Ash insoluble | 0·86| 0·94| 0·56| 0·66| 0·56 | 0·66| 1·06

in acids. | | | | | | |

Extract |42·00|37·40|43·20|40·60| 34·60 |29·60|26·20

Insoluble leaf|54·90|59·55|52·70|56·55| 60·75 |64·80|68·75

Tannin |18·66|16·31|18·00|16·05| 14·87 |13·70|12·26

Theine | 3·46| 2·20| 2·26| 1·39| 3·29 | 2·23| 2·35

--------------+-----+-----+-----+-----+--------+-----+-----

--------------+-------------------------------------------------------

|First Young Hyson, Regular Moyune.

| +----------------------------------------------

| |First Young Hyson, Plain Draw.

| | +----------------------------------------

| | |Second Young Hyson, Moyune.

Variety. | | | +-------------------------------

| | | |Third Young Hyson, Plain Draw.

| | | | +------------------------

| | | | |Choice Gunpowder.

| | | | | +----------------

| | | | | |Third Gunpowder.

--------------+--------+-----+--------+------+-------+----------------

| c. | c. | c. | c. | c. | c.

Price per lb. |28 to 30| 25 |17 to 18| 14 | 35 | 23

(wholesale).| | | | | |

| p.c. | p.c.| p.c. | p.c. | p.c. | p.c.

Total ash | 6·26 | 5·86| 5·84 | 6·20 | 5·76 | 5·50

Ash soluble in| 3·60 | 3·28| 3·36 | 3·34 | 3·26 | 3·14

water. | | | | | |

Ash insoluble | 2·66 | 2·58| 2·48 | 2·86 | 2·50 | 2·36

in water. | | | | | |

Ash insoluble | 0·64 | 0·58| 0·50 | 0·52 | 0·54 | 0·52

in acids. | | | | | |

Extract | 40·60 |41·00| 39·80 |30·40 | 39·60 |36·00

Insoluble leaf| 55·50 |57·70| 57·15 |61·95 | 56·70 |57·90

Tannin | 18·00 |19·96| 18·53 |16·99 | 20·09 |17·87

Theine | 2·26 | 2·30| 1·16 | 1·08 | 1·78 | 1·42

--------------+--------+-----+--------+------+-------+------

--------------+-----------------------------------------------

|Uncoloured Japan, Choicest, First Picking.

| +----------------------------------------

| |Coloured Japan, Good Medium,

| | First Picking.

| | +---------------------------------

Variety. | | |Coloured Japan, Good Medium,

| | | Third Picking

| | | +--------------------------

| | | | Japan Dust

| | | +--------------------------

| | | |Coloured, Fine.

| | | | +-------------------

| | | | |Uncoloured, Common.

--------------+------+------+------+------+-------------------

| c. | c. | c. | c. | c.

Price per lb. | 30 | 22 | 19 | 9 | 6

(wholesale).| | | | |

| p.c. | p.c. | p.c. | p.c. | p.c.

Total ash | 5·44 | 6·06 | 6·50 | 9·74 | 6·66

Ash soluble in| 3·46 | 2·84 | 2·90 | 1·48 | 2·78

water. | | | | |

Ash insoluble | 1·98 | 3·22 | 3·60 | 8·26 | 3·88

in water. | | | | |

Ash insoluble | 0·46 | 0·78 | 0·96 | 3·90 | 1·46

in acids. | | | | |

Extract |39·20 |36·40 |33·40 |31·80 |32·80

Insoluble leaf|56·85 |57·10 |59·90 |61·45 |60·05

Tannin |21·92 |18·27 |17·35 |15·66 |17·74

Theine | 1·54 | 1·66 | 0·74 | 0·82 | 2·43

--------------+------+------+------+------+-----

The following analyses of several kinds of spurious tea, received from

the U.S. Consuls at Canton and Nagasaki (Japan), have been made by the

author:--

-----------------------+-----------+-----------+-----------+----------

| 1. | 2. | 3. | 4.

-----------------------+-----------+-----------+-----------+----------

| per cent. | per cent. | per cent. | per cent.

Total ash | 8·62 | 8·90 | 7·95 | 12·58

Ash insoluble in water | 7·98 | 6·04 | 4·95 | 8·74

Ash soluble in water | 0·64 | 1·86 | 3·00 | 3·84

Ash insoluble in acid | 3·92 | 3·18 | 1·88 | 6·60

Extract | 7·73 | 14·00 | 12·76 | 22·10

Gum | 10·67 | 7·30 | 11·00 | 11·40

Insoluble leaf | 70·60 | 70·55 | 67·00 | 60·10

Tannin | 3·13 | 8·01 | 14·50 | 15·64

Theine | 0·58 | nil | 0·16 | 0·12

-----------------------+-----------+-----------+-----------+----------

1. Partially exhausted and refired tea-leaves, known as “_Ching Suey_”

(clear water), which name doubtless has reference to the weakness of a

beverage prepared from this article.

2. “Lie tea,” made from Wampan leaves.

3. A mixture of 10 per cent. green tea and 90 per cent. “lie tea.” It

is sometimes sold as “Imperial” or “Gunpowder” tea, and is stated to be

extensively consumed in France and Spain.

4. “Scented caper tea,” consisting of tea-dust made up into little

shot-like pellets by means of “Congou paste” (_i. e._ boiled rice), and

said to be chiefly used in the English coal-mining districts.

The following are the results of the analysis by American chemists of

samples representing 2414 packages of Indian tea.

Per cent. Average per cent.

Moisture 5·830 to 6·325 5·938

Extract 37·800 „ 40·350 38·841

Total ash 5·050 „ 6·024 5·613

Ash soluble in water 3·122 „ 4·280 3·516

Ash insoluble in water 1·890 „ 2·255 2·092

Ash insoluble in acid 0·120 „ 0·296 0·177

Insoluble leaf 47·120 „ 55·870 51·910

Tannin 13·040 „ 18·868 15·323

Theine 1·880 „ 3·24 2·736

FOOTNOTES:

[4] I.e. the United States.

[5] ‘Chemistry of Foods.’

[6] ‘Tea, Coffee, and Cocoa Analysis.’

[7] The degrees of temperature given in the text refer to the

Centigrade thermometer; their equivalents on the Fahrenheit scale can

be obtained by means of the formula 9/5C.° + 32 = F.°.

[8] In low grade, but unadulterated Congou tea, the extract

occasionally falls so low as 25 per cent.

COFFEE.

Coffee is the seed of the _Caffea Arabica_, indigenous to Abyssinia

and southern Arabia, and since naturalised in the West Indies, Ceylon,

Brazil, and other tropical countries. Its importance as an almost

universal beverage is only equalled by that of tea. The ancient history

of coffee is shrouded in great obscurity. It was unknown to the Romans

and Greeks, but its use is said to have been prevalent in Abyssinia

from the remotest time, and in Arabia it formed an article of general

consumption during the fifteenth century. From its introduction, in

1575, into Constantinople by the Turks, it gradually made its way into

all civilised countries. In 1690 it was carried by the Dutch from Mocha

to Java, whence specimens of the tree were taken to Holland and France.

Coffee houses were opened in London about the middle of the seventeenth

century, and in 1809 the first cargo of coffee was shipped to the

United States. As with many other articles of diet, the adulteration of

coffee has kept well apace with its increased consumption. The bean is

deprived of its external fleshy coatings before exportation, and is met

with in commerce in a raw, roasted, or ground condition. Bell[9] gives

the following analyses of two samples of coffee, both in the raw and

roasted state:--

---------------------------+---------------------+--------------------

| Mocha. | East Indian.

+----------+----------+----------+---------

| Raw. | Roasted. | Raw. | Roasted.

---------------------------+----------+----------+----------+---------

|per cent. |per cent. |per cent. |per cent.

Caffeine | 1·08 | 0·82 | 1·11 | 1·05

Saccharine matter | 9·55 | 0·43 | 8·90 | 0·41

Caffeic acids | 8·46 | 4·74 | 9·58 | 4·52

Alcohol extract (containing| 6·90 | 14·14 | 4·31 | 12·67

nitrogen and colouring | | | |

matter). | | | |

Fat and oil | 12·60 | 13·59 | 11·81 | 13·41

Legumin or Albumin | 9·87 | 11·23 | 11·23 | 13·13

Dextrine | 0·87 | 1·24 | 0·84 | 1·38

Cellulose (and insoluble | 37·95 | 48·62 | 38·60 | 47·42

colouring matter). | | | |

Ash | 3·74 | 4·56 | 3·98 | 4·88

Moisture | 8·98 | 0·63 | 9·64 | 1·13

+----------+----------+----------+---------

|100·00 |100·00 | 100·00 |100·00

---------------------------+----------+----------+----------+---------

Other authorities have obtained the following results:--

---------------------------+-------------------+---------+-------------

| König. | | Smethan.

+---------+---------+ Payen. |(Average of

| Raw. | Roasted.| Raw. |7 Varieties.)

| | | | Roasted.

---------------------------+---------+---------+---------+-------------

|per cent.|per cent.|per cent.| per cent.

Substances soluble in water| 27·44 | 27·45 | .. | ..

Nitrogen | 1·87 | 2·31 | .. | 2·26

Nitrogenous substances | 11·43 | 12·05 |11 to 13 | ..

Caffeine | 1·18 | 1·38 | 0·8 | ..

Caffetannic acid | .. | .. |3·5 to 5 | ..

Fat | 13·23 | 15·03 |10 to 13 | 10·99

Ethereal oil | .. | .. | 0·013 | ..

Sugar | 3·25 | 1·32 | .. | ..

Sugar and Dextrine | .. | .. | 15·5 | ..

Other non-nitrogenous | 31·52 | 38·41 | .. | ..

substances. | | | |

Cellulose | 27·72 | 24·27 | 34·0 | 29·28

Ash | 3·48 | 3·75 | 6·7 | 4·19

Soluble ash | .. | .. | .. | 3·37

Moisture | 11·19 | 3·19 | 12·0 | 2·87

---------------------------+---------+---------+---------+-------------

It will be noticed from these analyses that the amount of sugar is

greatly diminished by the process of roasting. According to some

analysts, the proportion of fat experiences an increase, but it is more

probable that this constituent is simply rendered more susceptible to

the action of solvents by a mechanical alteration of the structure of

the berry. Recent determinations of the ash in coffee place its average

proportion at 4 per cent.; 3·24 being soluble in water, and 0·74 per

cent. insoluble. The soluble extract in roasted coffee usually amounts

to about 30 per cent.

An analysis made by Beckurts and Kauder[10] gives the general

composition of roasted chicory, dried at 107°, as follows:--

Per cent.

Substances soluble in water 57·40

„ insoluble „ 41·90

Ash 7·66

Fat 0·73

Nitrogenous substances 7·12

Grape sugar 4·35

Cane sugar and dextrine 5·33

Starch 2·45

Other non-nitrogenous substances 49·13

Woody fibre 26·23

The most common adulterations to which coffee is liable consist

in the addition of chicory, caramel, and numerous roasted grains,

such as corn, wheat, and rye, as well as such roots and seeds as

dandelion, mangold wurzel, turnips, beans, peas, etc. The roasted and

ground article is naturally most exposed to falsification, although

letters patent have been issued for the fictitious manufacture of a

pressed “coffee bean,” containing absolutely no coffee. The addition

of chicory is by far the most prevalent adulteration of coffee. Of

thirty-four samples examined by Hassall, thirty-one (91 per cent.)

contained this root. In regard to the moral aspects of its use, it

can safely be asserted that, while the addition of chicory to coffee

is largely sanctioned, and indeed demanded by the existing tastes of

many coffee-drinkers, its use constitutes a true adulteration, and

should be condemned, unless its presence is prominently stated on the

label of the package. In chicory the active principles of coffee, which

exert valuable physiological effects on the system (viz. caffeine, the

essential oil, etc.), are totally absent; moreover, its comparative

cheapness is a constant temptation to employ a proportion largely in

excess of the amount requisite to produce any alleged improvement in

the flavour of the resulting admixture.

The sophistications of coffee may be detected, in a general way, by

physical tests, by chemical analysis, and by microscopic examination,

in which processes great aid is derived from the characteristic

properties exhibited by the pure roasted and ground berry which

distinguish it from its more usual adulterants.

(_a_) _Physical Examination._--The following tests, while not always

decisive in their results, are often of service.

A small portion of the suspected sample is gently placed upon the

surface of a beaker filled with cold water, and allowed to remain at

rest for about fifteen minutes. If pure, the sample does not imbibe the

water, but floats upon the surface without communicating much colour to

it; if chicory or caramel be present, these substances rapidly absorb

moisture and sink, producing brownish-red streaks in their descent,

which, by diffusion, impart a very decided tint to the entire liquid. A

similar coloration is caused by many other roasted roots and berries,

but not so quickly or to so great an extent. The test may be somewhat

modified by shaking the sample with cold water, and then allowing

the vessel to stand aside for a short time. Pure coffee rises to the

surface, little or no colour being imparted to the water; chicory,

etc., fall to the bottom as a sediment, and give a brownish colour to

the liquid.

If a small quantity of the sample is placed upon a clean plate of

glass, and moistened with a few drops of water, the pure coffee berries

remain hard, and offer resistance when tested with a needle; most

grains employed for their adulteration become softened in their texture.

A considerable portion of the mixture is treated with boiling water and

allowed to settle. Genuine coffee affords a clear and limpid infusion;

many foreign grains yield a thick gummy liquor, resulting from the

starchy and saccharine matters contained. An infusion of pure coffee,

if treated with solution of cupric acetate and filtered, will show

a greenish-yellow colour; if chicory be present, the filtrate will

be reddish-brown. As a rule, samples of ground coffee which are much

adulterated, pack together when subjected to a moderate pressure.

Owing to the low density of a coffee infusion (due to its almost entire

freedom from sugar), as compared with that of the infusions of most

roots and grains, it has been suggested by Messrs. Graham, Stenhouse

and Campbell, to apply the specific gravity determination of the

infusion obtained from the suspected sample as a means for detecting

adulteration. The results afforded are fairly approximate. The solution

is prepared by boiling one part of the sample with ten parts of water

and filtering. The following table gives the densities, at 15°·5, of

various infusions made in this manner:--

Acorns 1·0073

Peas 1·0073

Mocha coffee 1·0080

Beans 1·0084

Java coffee 1·0087

Jamaica coffee 1·0087

Costa Rica coffee 1·0090

Ceylon coffee 1·0090

Brown malt 1·0109

Parsnips 1·0143

Carrots 1·0171

Yorkshire chicory 1·0191

Black malt 1·0212

Turnips 1·0214

Rye meal 1·0216

English chicory 1·0217

Dandelion root 1·0219

Red beet 1·0221

Foreign chicory 1·0226

Mangold wurzel 1·0235

Maize 1·0253

Bread raspings 1·0263

Assuming the gravity of the pure coffee infusion to be 1·0086, and that

of chicory to be 1·0206, the approximate percentage of coffee, C, in a

mixture, can be obtained by means of the following equation, in which D

represents the density of the infusion:--

C = (1·00(1·020 - D)) / 12.

This was tested by mixing equal parts of coffee and chicory, and taking

the specific gravity of the infusion; it was 1·01408, indicating the

presence of 49 per cent. of coffee. Some idea of the amount of foreign

admixture (especially chicory) in ground roasted coffee may be formed

from the tinctorial power of the sample. It has already been mentioned

that coffee imparts much less colour to water than do most roasted

grains and roots. The table below shows the weights of various roasted

substances which must be dissolved in 2·000 parts of water in order to

produce an equal degree of colour:[11]--

Caramel 1·00

Mangold wurzel 1·66

Black malt 1·82

White turnips 2·00

Carrots 2·00

Chicory (darkest Yorkshire) 2·22

Parsnips 2·50

Maize 2·86

Rye 2·86

Dandelion root 3·33

Red beet 3·33

Bread raspings 3·36

Acorns 5·00

Over-roasted coffee 5·46

Highly-roasted coffee 5·77

Medium-roasted coffee 6·95

Peas 13·33

Beans 13·33

Spent tan 33·00

Brown malt 40·00

The comparative colour test may also be applied as follows:[12]--One

gramme each of the sample under examination, and of a sample prepared

by mixing equal parts of pure coffee and chicory, are completely

exhausted with water, and the infusions made up to 100 c.c. or more;

50 c.c. of the filtered extract from the suspected sample are then

placed in a Nessler cylinder, and it is determined by trial how many

c.c. of the extract from the standard mixture, together with enough

distilled water to make up the 50 c.c., will produce the same colour.

In calculating the chicory present, it is assumed that this substance

possesses three times the tinctorial power of coffee.

(_b_) _Chemical Examination._--Some of the chemical properties of

roasted coffee afford fairly reliable means for the detection of an

admixture of chicory. Coffee ash dissolves in water to the extent of

about 80 per cent.; of the ash of roasted chicory only about 35 per

cent. is soluble. Coffee ash is almost free from silica and sand, which

substances form a notable proportion of the constituents of the ash of

chicory.

The following (see p. 36) are the results obtained by the writer from

the analysis of the ash of coffee and chicory.

It will be observed from these analyses, that the most distinctive

features presented by coffee ash are the absence of soda, and the

small amounts of chlorine, ferric oxide and silica present. In these

respects, it is very different from the ash of chicory. The proportion

of phosphoric acid found in the latter is in excess of that given by

some authorities. Several analyses of chicory ash have been made by

the author, and, in every instance, the amount of phosphoric acid was

over 8 per cent.; in one sample of the ash of commercial chicory it

approximated 13 per cent.

-------------------------------+--------------+--------------

| Java Coffee. | Chicory Root

-------------------------------+--------------+--------------

| per cent. | per cent.

Percentage of ash | 3·93 | 4·41

-------------------------------+--------------+--------------

Potassa | 53·37 | 23·00

Soda | .. | 13·13

Lime | 5·84 | 9·40

Magnesia | 9·09 | 5·88

Alumina | 0·43 | ..

Ferric oxide | 0·53 | 5·00

Sulphuric acid | 3·19 | 9·75

Chlorine | 0·78 | 4·93

Carbonic acid | 15·26 | 4·01

Phosphoric acid | 11·26 | 8·44

Silica and sand | 0·25 | 16·46

-------------------------------+--------------+--------------

| 100·00 | 100·00

-------------------------------+--------------+--------------

Blyth gives the annexed table, showing the characteristic differences

between coffee and chicory ash:[13]--

------------------------+----------------+----------------

| Coffee Ash. | Chicory Ash.

------------------------+----------------+----------------

| per cent. | per cent.

Silica and sand | none | 10·69 to 35·88

Carbonic acid | 14·92 | 1·78 „ 3·19

Ferric oxide | 0·44 to 0·98 | 3·13 „ 5·32

Chlorine | 0·26 „ 1·11 | 3·28 „ 4·93

Phosphoric acid | 10·00 „ 11·00 | 5·00 „ 6·00

Total soluble ash | 75·00 „ 85·00 | 21·00 „ 35·00

------------------------+----------------+----------------

The following formula has been suggested for determining the percentage

of pure coffee, in mixtures:--

C = 2 ((100S - 174) / 3)

where S represents the percentage of soluble ash.

Another noteworthy difference between roasted coffee and chicory, is

the amount of sugar contained. As a rule, in roasted coffee, it ranges

from 0·0 to 1·2 per cent.; in roasted chicory, it varies from 12· to

18· per cent. The quantity of sugar in a sample can be determined by

Fehling’s method as follows:--

A standard solution of pure cupric sulphate is first prepared by

dissolving 34·64 grammes of the crystals (previously ground and dried

by pressing between bibulous paper) in about 200 c.c. of distilled

water; 173 grammes of pure Rochelle salt are separately dissolved

in 480 c.c. of a solution of sodium hydroxide of sp. gr. 1·14. The

solutions are then mixed and diluted with distilled water to one litre.

Each c.c. of the above solution represents 0·05 gramme of grape sugar.

The test is applied by taking 10 c.c. of the copper solution, adding

about four times its volume of water, and bringing it to the boiling

point. The coffee infusion is then gradually added from a burette,

until the copper salt is completely reduced to the red sub-oxide,

which point is recognised by the disappearance of its blue colour, and

can be more accurately determined by acidulating the filtered fluid

with acetic acid and testing it (while still hot) for any remaining

trace of copper with potassium ferrocyanide. In preparing the coffee

solution for the foregoing test, it is advisable to exhaust a weighed

quantity of the sample with hot water. The infusion is treated with

basic plumbic acetate so long as a precipitate forms; it is then

filtered, the precipitate being well washed, and the lead contained

is removed by conducting sulphuretted hydrogen gas through the fluid

which is subsequently again filtered and boiled until the dissolved gas

is expelled. The sugar determination is now made. Wanklyn employs the

following equation to estimate the amount of chicory in an adulterated

sample:--

E = ((S - 1)100) / 14,

where E is the percentage of chicory, and S the percentage of sugar.

According to the analysis of König, the proportions of sugar and other

constituents in some of the adulterants of coffee, are as follows:--

----------------------------+---------+---------+---------+---------

|Chicory. | Figs. | Acorns. | Rye.

----------------------------+---------+---------+---------+---------

|per cent.|per cent.|per cent.|per cent.

Water | 12·16 | 18·98 | 12·85 | 15·22

Nitrogenous substances | 6·09 | 4·25 | 6·13 | 11·84

Fat | 2·05 | 2·83 | 4·61 | 3·46

Sugar | 15·87 | 34·19 | 8·05 | 3·92

Other non-nitrogenous | 46·71 | 29·15 | 62· | 55·37

substances. | | | |

Cellulose | 11·0 | 7·16 | 4·98 | 5·35

Ash | 6·12 | 3·44 | 2·12 | 4·81

Substances soluble in water | 63·05 | 73·8 | .. | 45·11

----------------------------+---------+---------+---------+---------

Estimations of the amount of sugar obtained upon boiling the suspected

coffee with water containing a little sulphuric acid (see p. 37), and

the proportion of the sample which is soluble in hot water should be

made. The presence of chicory is shown by a decided increase in the

amount of soluble substances; that of rye, by the notable quantity of

sugar produced by the inversion with acid, due to the starch contained

in the grain.

In this connection, the following determinations of Krausch are of

interest:--

---------------------------------+----------+------------+----------

|Substances|Ready-formed| Sugar

|Soluble in| Sugar. | after

| Water. | |Inversion.

---------------------------------+----------+------------+----------

| per cent.| per cent. | per cent.

Roasted coffee | 23·81 | 0·20 | 24·59

„ chicory | 65·42 | 23·40 | 22·14

„ rye | 31·92 | .. | 75·37

„ coffee | | |

+ 10 per cent. chicory | 30·63 | 2·30 | 23·15

„ coffee | | |

+ 10 per cent. rye | 25·98 | 0·19 | 29·60

---------------------------------+----------+------------+----------

The presence of roasted rye, corn, and other grains in coffee, may be

qualitatively recognised by testing the cold infusion of the sample

with iodine solution for starch, which is not contained in a ready

formed state in coffee. Caffeine is absent in chicory and the other

usual adulterants of coffee, and the estimation of this alkaloid is of

decided service (see p. 21). Roasted coffee contains about 1 per cent.

of caffeine.

A popular brand of ground coffee received by the author for

examination, and labelled “Prepared Java Coffee,” had the following

approximate composition:--Coffee, 38; peas, 52; rye, 2; and chicory, 7

per cent.

A sample of “acorn” coffee, analysed by König, gave the following

results:--

Per cent.

Water 12·85

Nitrogenous substances 6·13

Fat 4·01

Sugar 8·01

Other non-nitrogenous substances 62·00

Cellulose 4·98

Ash 2·02

The non-nitrogenous constituents contained from 20 to 30 per cent. of

starch, and from 6 to 8 per cent. of tannic acid.

The composition of the well-known German coffee-substitutes, prepared

by Behr Bros., is stated to be as follows:--

“_Rye Coffee-substitutes._”

Per cent.

Substances soluble in water 61·33

Substances insoluble in water 36·45

Cellulose 9·78

Starch 8·34

Dextrine 49·51

Nitrogenous substances 11·87

Other non-nitrogenous substances 9·83

Fat 3·91

Ash 4·54

Moisture 2·22

“_Malt Coffee-substitute._”

Per cent.

{ Albuminoid substances 4·22

Soluble { Dextrine 50·19

in { Alcoholic extract 7·57

hot water { Inorganic matter, }

{ containing } 2·27

{ phosphoric acid, 0·54 }

Insoluble in hot water 35·00

Moisture 0·35

The raw coffee bean is sometimes subjected to a process termed

“sweating,” which consists in treating it with moist steam, the object

being to artificially reproduce the conditions present in the holds

of vessels, by means of which the bean is increased in size, and also

somewhat improved in colour and flavour. Another form of manipulation,

analogous to the facing of tea, is to moisten the raw bean with water

containing a little gum, and agitate it with various pigments, such as

indigo, Prussian blue, Persian berries, turmeric, alkanet, Venetian

red, soap-stone, chrome-yellow, and iron ochre. Mexican coffees are

sometimes made to resemble the more expensive Java in appearance.

The chemist of the New York City Board of Health has found in the

quantity of such treated coffee commonly taken to make a cup of the

beverage 0·0014 gramme of cupric arsenite. Indigo may be detected in

the artificially coloured product by treating a considerable portion

of the sample with dilute nitric acid, filtering and saturating the

filtrate with sulphuretted hydrogen. If indigo be present, it can now

be extracted upon agitating the solution with chloroform. Alkanet root

and Prussian blue are separated by warming the coffee with solution of

potassium carbonate, from which these pigments are precipitated upon

addition of hydrochloric acid.

(_c_) _Microscopic Examination._--Great aid to the chemical

investigation is afforded by the microscopic examination of ground

coffee. It is necessary to first become familiar with the appearance of

the genuine article--low magnifying powers being employed--and then

make comparative examinations of the adulterant suspected to be present.

The coffee bean mainly consists of irregular cells inclosed in very

thick walls which are distinguished by uneven projections. The cells

contain globules of oil. Most of the roots added to coffee exhibit

a conglomeration of cells (provided with thin walls) and groups of

jointed tubes, often quite similar to one another in structure. The

microscopic appearance of some of the starch granules, occasionally met

with in coffee mixtures, is represented on p. 100.

Of 151 samples of ground coffee recently purchased at random and tested

by various American chemists, 69 (45·7 per cent.) were found to be

adulterated.

FOOTNOTES:

[9] Op. cit.

[10] Pharm. Centralbl., 1885, p. 346.

[11] Graham, Stenhouse and Campbell.

[12] Leebody, ‘Chemical News,’ xxx. p. 243.

[13] ‘Foods: Composition and Analysis.’

COCOA AND CHOCOLATE.

Cocoa is prepared from the roasted seeds of the tree _Theobroma cacao_,

of the order _Byttneriaceæ_. It sometimes appears in commerce as

“cocoa-nibs” (_i. e._ partially ground), but it is more frequently sold

in the powdered state, either pure or mixed with sugar and starch, and

also often deprived of about one-half of its fat. Chocolate usually

consists of cocoa-paste and sugar flavoured with vanilla, cinnamon, or

cloves, and commonly mixed with flour or starch. According to Wanklyn,

the average composition of cocoa is as follows:--

Per cent.

Cocoa butter 50·00

Theobromine 1·50

Starch 10·00

Albumin, fibrine and gluten 18·00

Gum 8·00

Colouring matter 2·60

Water 6·00

Ash 3·60

Loss, etc. 0·30

R. Benzeman[14] has furnished the following averages of the results

obtained by the analysis of cocoa and chocolate. The air-dried cocoa

berries gave--husks, 13·00 per cent.; nibs, 87·00 per cent.:--

-------------------------------------+-------------+---------------

| | Chocolate made

| Cocoa Nibs. | from Cocoa and

| | Sugar.

-------------------------------------+-------------+---------------

| per cent. | per cent.

Moisture at 100° | 6·41 | 1·65

Fat | 51·47 | 22·57

Starch | 11·75 | 4·58

Other organic substances, | |

insoluble in water. | 18·03 | 8·58

Organic substances, soluble in water | 8·54 | 60·63

Mineral Ash | 3·80 | 1·99

-------------------------------------+-------------+---------------

| 100·00 | 100·00

-------------------------------------+-------------+---------------

Ash of insoluble substances | 0·89 | 0·30

-------------------------------------+-------------+---------------

Recent analysis of shelled cocoa-beans, made by Boussingault, gave the

following results:--

---------------------------+-----------+-----------

| Fresh. | Dry.

---------------------------+-----------+-----------

| per cent. | per cent.

Fat | 49·9 | 54·0

Starch and starch-sugar | 2·4 | 2·5

Theobromine | 3·3 | 3·6

Asparagine | traces | ..

Albumin | 10·9 | 11·8

„ gum | 2·4 | 2·5

Tartaric acid | 3·4 | 3·7

Tannin | 0·2 | 0·2

Soluble cellulose | 10·6 | 11·5

Ash | 4·0 | 4·4

Water | 7·6 | ..

Undetermined | 5·3 | 5·8

---------------------------+-----------+-----------

Dr. Weigman[15] obtained the following results from an examination of

several varieties of the shelled beans:--

---------------+-----------+-----------+-----------+-----------

| Water. | Fat. | Ash. | Nitrogen.

---------------+-----------+-----------+-----------+-----------

| per cent. | per cent. | per cent. | per cent.

Machala | 4·97 | 47·80 | 3·88 | 2·25

Arriba | 6·57 | 47·44 | 3·52 | 2·31

Caracas | 6·00 | 46·39 | 4·19 | 2·23

Puerto Cabello | 5·71 | 48·74 | 3·94 | 2·13

Surinam | 5·01 | 46·26 | 2·99 | 2·20

Trinidad | 6·07 | 45·74 | 2·04 | 2·04

Port au Prince | 4·73 | 48·58 | 3·89 | 2·33

---------------+-----------+-----------+-----------+-----------

The most important constituents of cocoa are the fat (cocoa-butter), and

the alkaloid (theobromine).

_Cocoa butter_ forms a whitish solid of 0·970 specific gravity, fusing

at 30°, and soluble in ether and in alcohol.

_Theobromine_ (C_{7}H_{8}N_{4}O_{2}) crystallises in minute rhombic

prisms, which are insoluble in benzol, but dissolve readily in boiling

water and alcohol. It sublimes at 170°. Theobromine is exceedingly rich

in nitrogen, containing over 20 per cent. of the element. In this and

many other respects it bears a great resemblance to theine.

The proportion of mineral ash in cocoa varies from 3·06 to 4·5 per cent.

James Bell[16] gives the following composition of the ash of Grenada

cocoa nibs:--

Per cent.

Sodium chloride 0·57

Soda 0·57

Potassa 27·64

Magnesia 19·81

Lime 4·53

Alumina 0·08

Ferric oxide 0·15

Carbonic acid 2·92

Sulphuric acid 4·53

Phosphoric acid 39·20

------

100·00

------

The most characteristic features of the ash of genuine cocoa are its

great solubility, the small amounts of chlorine, carbonates, and soda,

and the constancy of the proportion of phosphoric acid contained. Bell

has also analysed several samples of commercial cocoa. The following

will serve to illustrate their general composition:--

Per cent.

Moisture 4·95

Fat 24·94

Starch (added) 19·19

Sugar (added) 23·03

Non-fatty cocoa 27·89

------

100·00

------

Per cent.

Nitrogen 2·24

Ash 1·52

Cocoa, soluble in cold water 31·66

Ash in portion soluble in cold water 1·17

The comparatively low percentage of ash contained in prepared cocoas

and chocolate, is of use in indicating the amount of real cocoa present

in such mixtures. A large proportion of the mineral constituents of

cocoa are dissolved by directly treating it with cold water. Wanklyn

obtained in this way from genuine cocoa-nibs 6·76 per cent. organic

matter, and 2·16 per cent. ash, the latter chiefly consisting of

phosphates; a commercial cocoa gave, extract, 46·04 per cent.; ash,

1·04 per cent. The most common admixtures of cocoa and chocolate,

are sugar and the various starches. The addition of foreign fats,

chicory, and iron ochres, is also sometimes practised. Since prepared

cocoas are generally understood to contain the first-named diluents,

their presence can hardly be considered an adulteration, if the fact

is mentioned upon the packages. Many varieties of the cocoas of

commerce will be found to be deficient in cocoa-butter, a considerable

proportion of which has been removed in the process of manufacture.

This practice is also claimed to be justifiable, the object being to

produce an article unobjectionable to invalids, which is not always

the case with pure cocoa. In the analysis of cocoa the following

estimations are usually made:--

_Theobromine._--10 grammes of the sample are first repeatedly exhausted

with petroleum-naphtha. The insoluble residue is mixed with a small

quantity of paste, prepared by triturating calcined magnesia with a

little water, and the mixture evaporated to dryness at a gentle heat.

The second residue is boiled with alcohol and the alcoholic solution of

theobromine filtered and evaporated to dryness in a tared capsule. It

is then purified by washing with petroleum-naphtha and weighed. Bell

has verified the existence in cocoa of a second alkaloid, distinct

from theobromine, which crystallises in silky needles very similar to

theine.

_Fat._--The proportion of fat is readily determined by evaporating to

dryness the petroleum-naphtha used in the preceding estimation. As

already stated, it is generally present in a proportion of 50 per cent.

in pure cocoa; the amount contained in prepared soluble cocoas being

often less than 25 per cent. The English minimum standard is 20 per

cent.

_Ash._--The ash is determined by the incineration of a weighed portion

of the sample in a platinum dish. In prepared cocoas and chocolates,

the proportion of ash is considerably lower than in pure cocoa. It is

of importance to ascertain the amount of ash soluble in water (the

proportion in genuine cocoa is about 50 per cent.), and especially the

quantity of phosphoric acid contained. Assuming that prepared cocoa

contains 1·5 per cent. of ash, of which 0·6 per cent. consists of

phosphoric acid, and allowing that pure cocoa contains 0·9 per cent. of

phosphoric acid, Blyth adopts the following formula for calculating the

proportion of cocoa present in the article:--

(·6 × 100) / ·9 = 66·66 per cent.

_Starch._--A convenient method for estimating the starch is to

first remove the fatty matter of the cocoa by exhaustion with

petroleum-naphtha, and then boil the residue with alcohol. The

remaining insoluble matter is dried, and afterwards boiled until the

starch becomes soluble. It is next again boiled for several hours with

a little dilute sulphuric acid, after which the solution is purified

by addition of basic plumbic acetate. The liquid is then treated with

sulphuretted hydrogen, in order to remove the lead, and the sugar

contained in the filtered solution is determined by means of Fehling’s

solution, and calculated to terms of starch. The proportion of starch

normally present in cocoa is to be deducted from the results thus

afforded. The variety of starch contained in cocoa differs in its

microscopic appearance from the starches most frequently added.

_Sugar._--The sugar may be determined by evaporating the alcoholic

solution obtained in the preceding process, and then subjecting the

residue to the same method of procedure.

The proportion of woody fibre in cocoa can be approximately estimated

by the method of Henneberg and Stohman,[17] which consists in

extracting the fat with benzole, boiling the remaining substances for

half an hour, first with 1·25 per cent. sulphuric acid, then with

1·25 per cent. solution of potassium hydroxide. The residue is washed

with alcohol and with ether, and its weight determined. Unwashed

cocoa-berries, when treated in this manner, gave from 2 to 3 per cent.

of cellulose, while cocoa husks furnished from 10 to 16 per cent.

The presence of chicory in soluble cocoa and chocolate is easily

recognised by the dark colour of the extract obtained, upon digesting

the suspected sample with cold water; ochres and other colouring

matters are detected by the reddish colour of the ash as well as by its

abnormal composition. The addition of foreign fats to chocolates is

stated to be occasionally resorted to.

The melting point of pure cocoa-butter varies from 30° to 33°. The

identification of foreign fats can sometimes be accomplished by means

of their higher melting point, and by an examination of the separated

fat, according to Koettstorfer’s method (see p. 71). The table

following gives the melting points of various fats, and the number of

milligrammes of K(OH) required for the saponification of one gramme of

the same.

--------------------------+--------------+-------------

| |m.g. K(OH)

Fat. |Melting point.|to saponify

| |one gramme.

--------------------------+--------------+-------------

| ° ° |

Cocoa-butter | 30 to 33 |198 to 203

Arachidis oil | .. | 191·3

Sesamé oil | .. | 190·0

Cotton-seed and olive oil | .. | 191·7

Almond oil | .. | 194·5

Palm oil | 35 to 36 | 202·5

Lard | 32 „ 33 | 195·5

Mutton tallow (fresh) | 42·5 „ 45 | ..

Mutton tallow (old) | 43·5 | 196·5

Bone fat | 21 to 22 | 190·0

Beeswax | 63 | ..

--------------------------+--------------+-------------

Other tests have also been suggested for the detection of foreign fats

in cocoa-butter:--

(_a_) Treat the fat with two parts of cold ether; pure cocoa-butter

dissolves, forming a clear solution, whereas in presence of tallow or

wax a cloudy mixture is obtained.

(_b_) Dissolve 10 grammes of the suspected fat in benzole, and expose

the solution to a temperature of 0°. By this treatment a separation

of pure cocoa-butter in minute grains is produced. The liquid is now

heated to 14°·4, when the cocoa-fat will re-dissolve to a transparent

solution, while the presence of tallow will be recognised by the turbid

appearance of the liquid.

FOOTNOTES:

[14] Jahresberichte, 1883, p. 1002.

[15] Agrikulturchemische Versuchstation, in Münster.

[16] Op. cit.

[17] Repert. f. Analyt. Chemie, 1884, p. 345.

MILK.

Owing to the very important sanitary relations of milk as a model

food, the subject of its sophistication has during the past ten years

received particular notice at the hands of the food-chemist. The

investigations of our public sanitary authorities have shown that milk

adulteration is exceedingly common. It is stated upon good authority

that until quite recently (1883) the 120 millions of quarts of milk

annually brought into New York city were intentionally diluted with

40 millions of quarts of water, the resulting product rivalling in

richness the famous compound once lauded by the philanthropic Squeers.

The results of the examination of milk instituted by the New York State

Board of Health are given below, in which, however, the specimens of

skimmed milk are not included:--

------+-------------------+--------------------+--------------

Year. | Number of Samples | Number showing | Per cent. of

| tested. | addition of Water. | Adulterated.

------+-------------------+--------------------+--------------

1880 | 1514 | 167 | 11·0

1881 | 1110 | 51 | 4·6

1882 | 1775 | 120 | 6·7

------+-------------------+--------------------+--------------

From October 1883 to March 1884, of 241 samples of milk examined by the

Public Analyst of Eastern Massachusetts, 21·37 per cent. were watered;

of 1190 samples tested during the year 1884, 790 were watered.[18]

Over 73 per cent. of the milk supplied to the city of Buffalo in

1885 was found to be adulterated. A very marked improvement in the

quality of the milk received in New York city has taken place since the

appointment of a State Dairy Commissioner (1884). Under the direction

of this official the metropolitan milk supply has been subjected to a

most rigid inspection, and with very satisfactory results. During the

years 1884 and 1885 nearly 45,000 samples of milk were examined.

A very common sophistication practised upon milk consists in the

partial or complete removal of its cream. This process of skimming is

conducted at establishments called “creameries,” of which sixty-three

were formerly known to send their impoverished product to New York

city. The State Dairy Commissioner has likewise accomplished much

towards stopping this form of adulteration.

Milk is the secretion of the mammary glands of female _mammalia_. It is

an opaque liquid, possessing a white, bluish-white, or yellowish-white

colour, little or no odour, and a somewhat sweetish taste. At times

it exhibits an amphigenic reaction, _i. e._ it turns red litmus blue

and blue litmus red. From the examination of nearly one thousand

cows in the States of New York, New Jersey, and Connecticut, the

_minimum_ specific gravity of milk was found to be 1·0290, the

_maximum_ being 1·0394. The opacity of milk is only apparent, and is

due to the presence of fatty globules held in suspension; these under

the microscope are seen to be surrounded by a transparent liquid.

Upon allowing milk to remain at rest for some time it experiences

two changes. At first, a yellowish-white stratum of cream rises to

the surface, the lower portion becoming bluish-white in colour and

increasing in density. If this latter is freed from the cream and

again set aside, it undergoes a further separation into a solid

body (_curd_), and a liquid (_whey_). This coagulation of the curd

(_caseine_) is immediately produced by the addition of rennet, and of

many acids and metallic salts.

The essential ingredients of milk are water, fat, caseine, sugar

(lactose), and inorganic salts. The following table, collated by

Mr. Edward W. Martin,[19] exhibits the results obtained by numerous

authorities from the analysis of pure cow’s milk:--

--------------+-------+------+-------+-----+------+------+--------+------

Authority or |Number | | Total | |Solids| | |

Analyst. | of |Water.|solids.|Fat. | not |Sugar.|Caseine.|Salts.

| cows. | | | | fat. | | |

--------------+-------+------+-------+-----+------+------+--------+------

| | p.c. | p.c. | p.c.| p.c. | p.c. | p.c. | p.c.

James Bell | 216 |87·17 | 12·83 | 3·83| 9·00 | .. | .. | 0·71

| | | | | | | |

James Bell | 24 |86·78 | 13·22 | 4·12| 9·10 | .. | .. | 0·72

|dairies| | | | | | |

| | | | | | | |

C. Estecourt | 22 |87·26 | 12·74 | 3·37| 9·37 | .. | .. | ..

|dairies| | | | | | |

| | | | | | | |

J. Carter Bell| 183 |86·40 | 13·60 | 3·70| 9·90 | .. | .. | 0·76

J. Cameron | 42 |86·53 | 13·47 | 4·00| 9·47 | .. | .. | ..

C. Cameron | 40 |87·00 | 13·00 | 4·00| 9·00 | 4·28 | 4·10 | 0·62

C. Cameron | 100 |86·75 | 13·85 | 4·60| 9·25 | .. | .. | ..

| | | | | | | |

Fleischmann } | 120 |87·78 | 12·22 | 3·20| 9·02 | .. | .. | ..

and Veith } | | | | | | | |

| | | | | | | |

Veith | 60 |87·20 | 12·80 | 3·10| 9·70 | .. | .. | ..

Veith | 9120 |86·97 | 13·03 | 3·52| 9·51 | .. | .. | ..

Wanklyn |Average|87·50 | 12·50 | 3·20| 9·30 | .. | .. | ..

| | | | | | | |

A. Wynter } | „ |86·87 | 13·13 | 3·50| 9·63 | .. | .. | ..

Blyth } | | | | | | | |

| | | | | | | |

Marchand | „ |87·15 | 12·85 | 3·55| 9·30 | .. | .. | ..

| | | | | | | |

Henry and } | „ |87·02 | 12·98 | 3·13| 9·85 | 4·77 | 4·48 | 0·60

Chevalier } | | | | | | | |

| | | | | | | |

Vernois } | „ |86·40 | 13·60 | 3·60|10·00 | .. | .. | ..

Becquerel } | | | | | | | |

| | | | | | | |

Payen | „ |86·60 | 13·40 | 3·50| 9·90 | .. | .. | ..

O. C. Wiggin | 58 |85·92 | 14·08 | 4·01|10·07 | 4·29 | 4·99 | 0·79

E. Calder | 27 |87·23 | 12·77 | 3·32| 9·45 | .. | .. | ..

Sharpless | 34 |85·85 | 14·15 | 4·62| 9·53 | 4·82 | 4·06 | 0·65

Haidlen |Average|87·30 | 12·70 | 3·00| 9·70 | .. | .. | ..

Letherby | „ |86·00 | 14·00 | 3·90|10·10 | 5·20 | 4·10 | 0·80

J. König | „ |87·30 | 12·70 | 3·00| 9·70 | 5·00 | 4·00 | 0·70

Boussingault | „ |87·40 | 12·60 | 4·10| 8·50 | 5·10 | 3·20 | 0·70

Muspratt | „ |86·43 | 13·57 | 4·43| 9·14 | 4·73 | 3·74 | 0·67

Dieulafait | „ |87·64 | 12·36 | 3·11| 9·25 | 4·22 | 4·18 | 0·85

Gorup-Bezanez | „ |85·70 | 14·30 | 4·31| 9·99 | 4·04 | 5·40 | 0·55

Brinton | „ |86·00 | 14·00 | 4·50| 9·50 | 3·50 | 5·50 | 0·70

| | | | | | | |

Chandler | 1700 |87·45 | 12·55 | 3·83| 8·72 | .. | .. | ..

| qts. | | | | | | |

| | | | | | | |

Newton |Average|87·50 | 12·50 | 3·50| 9·00 | .. | .. | ..

Bartley | „ |87·50 | 12·50 | 3·50| 9·00 | .. | .. | ..

White | „ |87·50 | 12·50 | 3·50| 9·00 | .. | .. | ..

Waller | „ |87·50 | 12·50 | 3·20| 9·30 | .. | .. | ..

Babcock | „ |85·53 | 14·47 | 5·09| 9·39 | 5·15 | 3·57 | 0·67

Church | „ |86·30 | 13·70 | 3·70|10·00 | 5·10 | 4·10 | 0·80

Edward Smith | „ |86·40 | 13·60 | 3·61| 9·90 | 3·80 | 5·52 | 0·66

Martin | „ |86·50 | 12·50 | 3·20| 9·30 | .. | .. | 0·67

--------------+-------+------+-------+-----+------+------+--------+------

Mr. Martin obtained the following results from the examination of

cream separated by centrifugal force, and of skimmed milk:--

-----------+----------+-------------

| Cream. |Skimmed Milk.

-----------+----------+-------------

| per cent.| per cent.

Water | 52·21 | 90·34

Fat | 41·16 | 0·15

Sugar | 3·11 | 3·98

Caseine | 3·40 | 4·80

Salts | 0·12 | 0·78

-----------+----------+-------------

The proportion of mineral constituents in milk usually ranges between

0·7 and 0·8 per cent. The average composition of milk ash is as

follows:[20]--

Per cent.

Potassa 24·5

Soda 11·0

Lime 22·5

Magnesia 2·6

Ferric oxide 0·3

Phosphoric anhydride 26·0

Sulphuric anhydride 1·0

Chlorine 15·6

-----

103·5[21]

The tabulation below gives the composition of human milk and the milk

of various animals:--

------------+--------+------+-------+------+--------+-------+---------

|Specific|Water.| Milk | Fat. |Caseine.| Milk |Inorganic

|Gravity.| |Solids.| | |Sugar. | Salts.

------------+--------+------+-------+------+--------+-------+---------

| | p.c. | p.c. | p.c.| p.c. | p.c. | p.c.

White woman | 1·0315 |87·806|12·194 | 4·021| 3·523 | 4·265 | 0·28

Coloured | | | | | | |

woman | .. |86·34 |13·66 | 4·03 | 3·32 | 5·71 | 0·61

Mare | 1·0310 |91·310| 9·690 | 1·055| 1·953 | 6·285 | 0·397

Goat | 1·0323 |86·36 |13·64 | 4·36 | 4·70 | 4·00 | 0·62

Ewe | 1·0380 |82·94 |17·00 | 6·97 | 5·40 | 3·63 | 0·97

Sow | 1·0440 |81·80 |18·20 | 6·00 | 5·30 | 6·07 | 0·83

Canine | 1·0360 |77·26 |22·74 |10·64 | 9·21 | 2·49 | 0·44

Ass | 1·0330 |91·95 | 8·05 | 0·11 | 1·82 | 6·08 | 0·34

Camel | |86·94 |13·06 | 2·90 | 3·67 | 5·78 | 0·66

| | | | | \ | / |

Hippopotamus| .. |90·43 | 9·57 | 4·51 | 4·40 | 0·11

Elephant | .. |66·697|33·303 |22·070| 3·212 | 7·392 | 0·629

Porpoise | .. |41·11 |58·89 |45·80 | 11·19 | 1·33 | 0·57

Cat | .. |81·62 |18·38 | 3·33 | 9·55 | 4·91 | 0·58

Llama | .. |89·55 |10·45 | 3·15 | 0·90 | 5·60 | 0·80

------------+--------+------+-------+------+--------+-------+---------

Several varieties of preserved and condensed milk have, for a number of

years, been placed upon the market. The composition of the best-known

brands of these preparations is as follows:--

PRESERVED MILK.

----------------------+---------+---------+---------+---------+------

| | |Cane and | |

Brand. | Water. | Fat. | Milk |Caseine. |Salts.

| | | Sugar. | |

----------------------+---------+---------+---------+---------+------

| p.c. | p.c. | p.c. | p.c. | p.c.

Alderney | 30·05 | 10·08 | 46·01 | 12·04 | 1·82

Anglo-Swiss (American)| 29·46 | 8·11 | 50·41 | 10·22 | 1·80

„ „ (English)| 27·80 | 8·24 | 51·07 | 10·80 | 2·09

„ „ (Swiss) | 25·51 | 8·51 | 53·27 | 10·71 | 2·00

Eagle | 27·30 | 6·60 | 44·47 | 10·77 | 1·86

Crown | 29·44 | 9·27 | 49·26 | 10·11 | 1·92

----------------------+---------+---------+---------+---------+------

CONDENSED MILK.

-------------------+---------+---------+---------+---------+---------

| | |Cane and | |

Brand. | Water. | Fat. | Milk |Caseine. | Salts.

| | | Sugar. | |

-------------------+---------+---------+---------+---------+---------

|per cent.|per cent.|per cent.|per cent.|per cent.

American | 52·07 | 15·06 | 16·97 | 14·26 | 2·80

New York | 56·71 | 14·13 | 13·98 | 13·18 | 2·00

Granulated Milk Co.| 55·43 | 13·16 | 14·84 | 14·04 | 2·53

Eagle | 56·01 | 14·02 | 14·06 | 13·90 | 2·01

-------------------+---------+---------+---------+---------+---------

ANALYSIS.

The principal adulterations of milk (watering and skimming), are

detected by taking its specific gravity, and making quantitative

determinations of the total milk solids, the fat, and the milk solids

not fat. Of these criteria, the last-mentioned is the most constant and

reliable.

_Physical Examination._

_a. Specific Gravity._--The instrument employed by the New York health

inspectors for testing milk is a variety of the hydrometer, termed

the lactometer, and its use, which is based upon the fact that under

ordinary conditions watered milk possesses a decreased density, is

certainly of great value as a preliminary test. The Board of Health

lactometer indicates specific gravities between 1·000 (the density of

water) and 1·0348. On its scale 100° represents the specific gravity of

1·029 (taken as the minimum density of genuine milk), and 0 represents

the density of water; the graduations are extended to 120°, equivalent

to a specific gravity of 1·0348. In taking an observation with the

lactometer, the standard temperature of 15° should be obtained,

_and the colour and consistency of the milk noted_. If these latter

properties indicate a dilution of the sample, and the instrument sinks

below the 100° mark, it is safe to assume that the milk has been

watered. The scale is so constructed that the extent of the dilution

is directly shown by the reading, _e. g._ if the lactometer sinks to

70° the sample contains 70 per cent. of pure milk and 30 per cent.

of water. As the standard of specific gravity (1·029) selected for

the 100° mark of the lactometer is the _minimum_ density of unwatered

milk, it is evident that the readings of the instrument will almost

invariably indicate an addition of water less than has actually taken

place. It would therefore appear that, under normal circumstances,

the standard adopted by the New York Board of Health errs on the side

of too much leniency toward the milk dealer. Cream being lighter than

water, a sample of skimmed milk will possess a greater specific gravity

than the pure article, and it is possible to add from 10 to 20 per

cent. of water to it and still have the resulting admixture stand at

100° when tested by the lactometer. Vehement attempts have been made in

court and elsewhere to impeach the accuracy of the indications afforded

by the lactometer. These have been mainly founded upon the fact that

a sample of milk unusually rich in cream will have a lower density

than a poorer grade, so that it is quite possible that milk of very

superior quality may show a gravity identical with that of a watered

specimen. Great stress has been laid upon this by the opponents of the

measures to control milk adulteration adopted by the public sanitary

authorities. They have contended that a chemical analysis should be

made. Recourse to this method would, however, involve a greater amount

of time than it is usually practicable to devote to the examination

of the numerous samples daily inspected; moreover, the process is

resorted to whenever the indications of the lactometer leave the

inspector in doubt. With the exercise of ordinary intelligence this

contingency seldom arises, as the proportion of cream required to

reduce the specific gravity to that of a watered sample would be more

than sufficient to obviate any danger of mistaking the cause of the

decreased density. In this connection it should be stated, that the

average lactometric standing of about 20,000 samples of milk, examined

by the New York State Dairy Commissioner in the year 1884, was 110°,

equivalent to a specific gravity of 1·0319.

The following table shows the value of lactometer degrees in specific

gravity:--

VALUE OF LACTOMETER DEGREES IN SPECIFIC GRAVITY.

-----------+-----------

Lactometer.| Gravity.

-----------+-----------

0 | 1·00000

1 | 1·00029

2 | 1·00058

3 | 1·00087

4 | 1·00116

5 | 1·00145

6 | 1·00174

7 | 1·00203

8 | 1·00232

9 | 1·00261

10 | 1·00290

11 | 1·00319

12 | 1·00348

13 | 1·00377

14 | 1·00406

15 | 1·00435

16 | 1·00464

17 | 1·00493

18 | 1·00522

19 | 1·00551

20 | 1·00580

21 | 1·00609

22 | 1·00638

23 | 1·00667

24 | 1·00696

25 | 1·00725

26 | 1·00754

27 | 1·00783

28 | 1·00812

29 | 1·00841

30 | 1·00870

31 | 1·00899

32 | 1·00928

33 | 1·00957

34 | 1·00986

35 | 1·01015

36 | 1·01044

37 | 1·01073

38 | 1·01102

39 | 1·01131

40 | 1·01160

41 | 1·01189

42 | 1·01210

43 | 1·01247

44 | 1·01276

45 | 1·01305

46 | 1·01334

47 | 1·01363

48 | 1·01392

49 | 1·01421

50 | 1·01450

51 | 1·01479

52 | 1·01508

53 | 1·01537

54 | 1·01566

55 | 1·01595

56 | 1·01624

57 | 1·01653

58 | 1·01682

59 | 1·01711

60 | 1·01740

61 | 1·01769

62 | 1·01798

63 | 1·01827

64 | 1·01856

65 | 1·01885

66 | 1·01914

67 | 1·01943

68 | 1·01972

69 | 1·02001

70 | 1·02030

71 | 1·02059

72 | 1·02088

73 | 1·02117

74 | 1·02146

75 | 1·02175

76 | 1·02204

77 | 1·02233

78 | 1·02262

79 | 1·02291

80 | 1·02320

81 | 1·02349

82 | 1·02378

83 | 1·02407

84 | 1·02436

85 | 1·02465

86 | 1·02494

87 | 1·02523

88 | 1·02552

89 | 1·02581

90 | 1·02619

91 | 1·02639

92 | 1·02668

93 | 1·02697

94 | 1·02726

95 | 1·02755

96 | 1·02784

97 | 1·02813

98 | 1·02842

99 | 1·02871

100 | 1·02900

101 | 1·02929

102 | 1·02958

103 | 1·02987

104 | 1·03016

105 | 1·03045

106 | 1·03074

107 | 1·03103

108 | 1·03132

109 | 1·03161

110 | 1·03190

111 | 1·03219

112 | 1·03248

113 | 1·03277

114 | 1·03306

115 | 1·03335

116 | 1·03364

117 | 1·03393

118 | 1·03422

119 | 1·03451

120 | 1·03480

-----------+----------

_Chemical Examination._

_b. Water, Total Solids, and Ash._--Five grammes of the fresh milk are

weighed in a tared platinum dish, having a flat bottom, which is placed

on a water-bath, where it is allowed to remain for about three hours.

It is then transferred to a water-oven, and the dish is subsequently

weighed, from time to time, until the weight becomes constant. The loss

in weight is the _water_ present; the difference between the weight

of the platinum capsule and its weight with the remaining contents

gives the amount of _total solids_, which, in milk of good quality,

should not be under 12 per cent. The inorganic salts (ash) can now

be determined by carefully incinerating the residual contents of the

capsule. Too high a temperature is to be avoided in this process, in

order to prevent the fusion of the ash, which should, however, be

ignited until it shows a greyish-white colour. The amount of ash in

genuine milk ranges from 0·70 to 0·80 per cent. The addition of water

naturally decreases this proportion as well as that of the total

milk-solids.

_c. Fat, Milk Solids not Fat, Caseine, and Milk Sugar._--An approximate

estimation of the fat in milk was formerly made by the use of the

_creamometer_. This instrument consists simply of a long glass tube,

provided at its upper end with a scale. The milk under examination is

introduced into the tube and allowed to remain at rest for about 24

hours, or until the stratum of cream has completely collected upon

its surface; the quantity is then read off by means of the attached

scale. The results afforded by the creamometer are, however, far

from reliable. Cream is really milk rich in fat, caseine, etc., and

the quantitative relation it bears to the true amount of fat present

is not always a direct one. A recent form of _lactoscope_, devised

by Feser, is less objectionable, and is in very general use for the

rapid estimation of fat in milk. It consists essentially of a glass

cylinder, provided with two scales, one being graduated into c.c., the

other, into percentages of fat. In the lower end of the instrument is

a contraction, in which is placed a cylindrical piece of white glass,

graduated with well-defined black lines. In using the lactoscope, 4

c.c. of the milk are introduced into the instrument by means of a

pipette, and water is gradually added, with shaking, until the black

marks on the small white cylinder become just visible. Upon now

referring to the c.c. scale, the quantity of water used to effect the

necessary dilution is ascertained, and the corresponding percentage of

fat in the sample is indicated by the percentage scale.[22]

In the gravimetric determination of the fat (butter), 10 grammes of the

milk are put into a tared platinum dish, containing a weighed amount of

dry sand. The milk is evaporated as previously directed, the mixture

being constantly stirred with a small platinum spatula. The residue

is repeatedly treated with warm ether or petroleum naphtha of 70° B.,

and the solutions poured upon a small filter. The several filtrates are

collected in a tared beaker, and cautiously evaporated, until constant

weight is obtained. This will give the amount of _fat_. The undissolved

residue remaining in the platinum capsule, or the difference between

the quantity of fat and that of the total milk-solids, affords the

proportion of _milk solids not fat_ contained, which, in unadulterated

milk, should amount to 9 per cent. It has been determined by

experiment, that every percentage of milk-solids not fat, increases

the specific gravity of milk 0·00375, whereas each percentage of fat

decreases the gravity 0·0010, and the proportion of solids not fat can

be calculated from the data afforded by the lactometer and Feser’s

lactoscope by means of the formula:--

(S - A) / 0·00375,

where S is the specific gravity of the milk, as shown by the

lactometer, and A is the remainder obtained upon multiplying the

percentage of fat indicated by the lactoscope by 0·001 and subtracting

the residue from 1·0000.

The residue remaining after the extraction of the fat is treated with

warm water containing a few drops of acetic acid, or with dilute (80

per cent.) alcohol, in order to remove the sugar. The residue is

dried until it ceases to decrease in weight, and is then weighed. The

difference between the original weight of the sand and the weight of

the sand and residue combined represents approximately the amount of

_caseine_ (albuminoids) present. As this contains a certain proportion

of ash it is to be subsequently ignited, and the ash obtained deducted

from the first weight. The alcoholic sugar solution is evaporated to

dryness and weighed. The residue is then incinerated and the weight

of ash is subtracted. The difference is the amount of _milk sugar_

contained. The sugar may likewise be determined by means of Fehling’s

solution (see pp. 37, 111). About 50 c.c. of the milk is warmed with

a small quantity of acetic acid to precipitate the caseine, which is

removed by filtration, and the filtrate diluted to 500 c.c.; the test

is then applied. 10 c.c. of the copper solution represents 0·067 gramme

of milk sugar.

The sugar in milk can also be estimated by the polariscope (see under

Sugar, p. 112). In case the Ventzke-Scheibler instrument is used, 65·36

grammes of the sample are weighed out and introduced into a 100 cc.

flask; about 5 cc. of plumbic basic acetate solution is added, and the

liquid is well shaken, and then allowed to stand at rest for a few

minutes. It is next filtered, its volume made up to the 100 cc. mark,

and the 20 cm. tube filled and the reading made; this divided by 2

gives the percentage of sugar in the milk.

Mr. A. Adams[23] has recently proposed a method of milk analysis which

consists in first placing 5 cc. of the sample in a tared beaker, and

then introducing a weighed paper coil made of blotting paper from

which all fatty matter has previously been removed by washing with

ether. As soon as the milk is completely absorbed, the paper coil is

removed and dried at 100°. The increase of weight gives the amount of

_total solids_. The _fat_ is next extracted by petroleum naphtha or

ether, and its weight determined. The proportion of _solids not fat_ is

ascertained by again drying and weighing the exhausted coil.

The standards adopted by the English Society of Public Analysts for

pure milk, are:--

Per cent.

Specific gravity 1·030

Ash 0·70

Solids not fat 9·00

Fat 2·50

Total solids 11·50

Water 88·50

In the State of New York, the legal standards for milk are that it

shall not contain more than 88 per cent. of water, nor less than 12 per

cent. of milk solids, and 3 per cent. of fat.

In Massachusetts the law fixing a chemical standard of purity for milk

reads: “In all cases of prosecution, if the milk shall be shown upon

analysis to contain more than 87 per cent. of water, or to contain less

than 13 per cent. of milk solids, it shall be deemed, for the purpose

of this Act, to be adulterated.”

The Board of Health of New Jersey fixes the minimum amount of total

solids at 12 per cent. and the maximum amount of water at 88 per cent.

In Paris, the minimum limits _for condemnation_ are the following:--

Fat, 2·70; milk-sugar, 4·50; caseine, albumen, and ash, 4·30; total

solids, 11·50.

The following proportion can be employed in the calculation of the

amount of pure milk (_x_) contained in a suspected sample:--

From the total solids:--

12·5: total solids found = 100 : _x_.

From the solids not fat:--

9·30: solids not fat = 100 : _x_.

From the sugar:--

4·40: sugar found = 100 : _x_.

From the specific gravity:--

1·030 : sp. gr. = 100 : _x_.

In most cases the determination of the total milk-solids and the fat

(the difference being the solids not fat) furnishes all the data

required for determining the amount of watering which a sample of milk

has undergone. The Society of Public Analysts use 9 as the average

percentage of solids not fat in pure milk (which is generally

considered as too low) and adopt the formula:--

100/9 S = _x_,

in which _x_ represents the percentage of genuine milk, and S the

solids not fat.

PLATE IV.

[Illustration: Cream × 420.]

[Illustration: Cows Milk × 420.]

ARTOTYPE. E. BIERSTADT, N. Y.

In skimmed milk the percentage of fat removed (_x_) can be ascertained

by the formula:--

(2·5) / (9·0) S - _f_ = _x_,

in which S = solids not fat, and _f_ = the fat found. In case the

sample has been subjected to both skimming and watering, the water

added (_x_) can be calculated from the formula[24]:--

100 - (100 + 2·5) / 9 S - _f_ = _x_.

The addition of mineral salts to milk is detected by the increased

proportion of ash found; the presence of an abnormal amount of common

salt by the high proportion of chlorine present in the ash, which

in pure milk should never exceed 0·14 per cent. The use of sodium

bicarbonate, borax, etc., is also detected by the analysis of the

ash. Glycerine, salicylic acid, flour, and starch, if added, can be

extracted from the milk-solids and their identity established by the

usual characteristic reactions.

The microscope is of great service in the determination of the quality

of milk, and especially in the detection of the presence of abnormal

bodies, such as pus, colostrum cells, and blood. In pure cow’s milk the

globules are in constant motion; their usual size is 1/5000 of an inch,

but this depends upon the nature of the food used. Plates IV. and V.,

which represent cream, pure milk, skimmed milk, and milk containing

colostrum cells, were taken from photo-micrographic negatives furnished

through the kindness of Mr. Martin.

Numerous cases of severe illness have from time to time been developed

by the use of milk which was apparently free from any of the usual

adulterants. In a recent issue of the ‘Philadelphia Medical News’

(Sept. 1886) an instance of wholesale milk poisoning at Long Branch is

described, and the results reached by a careful study of the epidemic

are given. It was demonstrated that warm milk, fresh from the cow, if

placed in closed cans under conditions which retarded the dissipation

of its heat, may suffer fermentation resulting within a few hours in

the genesis of a sufficient quantity of a poisonous ptomaine (termed

_tyrotoxicon_) to produce dangerous toxic effects in those drinking it.

Tyrotoxicon was isolated from the milk, and obtained in needle-shaped

crystals, which reduced iodic acid and gave a blue coloration when

treated with potassium ferricyanide or ferric chloride. Prof. Victor

C. Vaughan[25] discovered the same alkaloid in poisonous cheese, and

has also detected its presence in ice-cream that had been the cause

of sickness. In this connection it is of importance to note that

the addition of gelatine to ice-cream is occasionally practised:

in case this substance is used while in a state of incipient

decomposition, the danger of the bacteria and other organisms present

subsequently resuming activity is considerable. It has been repeatedly

and conclusively demonstrated that milk from cows affected with

tuberculosis and other complaints, is capable of propagating the seeds

of disease, especially in children. The presence of impure water in

milk constitutes another source of danger. A test based upon the fact

that water which has received sewage contamination often contains

nitrites, is applied by first coagulating the suspected milk with

acetic acid, then filtering and adding to the filtrate a few cc. of an

equal mixture of sulphanilic acid and naphthylamine sulphate, when, in

presence of nitrites, a rose-red colour will be produced.

PLATE V.

[Illustration: Skimmed Cows Milk × 420.]

[Illustration: Colostrum in Cows Milk × 420.]

ARTOTYPE. E. BIERSTADT, N. Y.

FOOTNOTES:

[18] In 1885, out of 2024 samples tested, 880 fell below the standard

of 13 per cent. total solids.

[19] Second Annual Report of the New York State Dairy Commissioner,

1886.

[20] Dammer’s ‘Lexikon der Verfälschungen,’ 1887, p. 592.

[21] 3·50 per cent. should be deducted for chlorine and oxygen.

[22] For description of the “Lactocrete,” see ‘Analyst,’ Jan. 1887.

[23] ‘Analyst,’ x. pp. 46-54.

[24] Blyth.

[25] “Ein Ptomain aus giftigem Käse,” Zeit. f. Phys. Chem., x. p. 2,

1886.

BUTTER.

Butter is the fat of milk, containing small proportions of caseine,

water, and salt (the latter mostly added), and possessing a somewhat

granular structure. In its preparation the fat-globules of cream are

made to coalesce by the process of churning, and are removed from

the residual buttermilk. Its colour, due to lactochrome, varies from

white to yellow, according to the breed and food of the cow. The

fatty constituents of butter are butyric, caproic, caprylic, capric,

myristic, palmitic, stearic, and oleic acids, which are combined with

glycerine as ethers; the first four are soluble in hot water, the

remainder insoluble. It is very probable that butter fat is composed of

complex glycerides, _i. e._ tri-acid (presumably oleic, palmitic, and

butyric) ethers, of the following character:--

{O.C_{4} H_{7}O

C_{3} H_{5} {O.C_{16}H_{31}O

{O.C_{18}H_{33}O

The table on p. 64 exhibits a summary of the results obtained by

various chemists by the analysis of numerous specimens of genuine

butter.

Dr. Elwyn Waller found the following variations in the constituents of

pure butter:--Fat, from 83 to 85; water, from 8 to 10; curd, from 1 to

3; salts, from 3 to 5 per cent.

Butter fat fuses at 28° to 37°, and at 37°·7 its specific gravity

ranges from 0·91200 to 0·91400. The most common adulterations of

butter consist in the addition of water, salt, colouring matters, and

various foreign fats (notably oleomargarine). The first two admixtures

are easily recognised by the proximate analysis; the detection of the

last sophistication involves a somewhat elaborate examination of the

fatty constituents of the butter.

-----------------+--------+---------------------+---------------------

| No. | Water. | Fats.

Analyst. | of |------+------+-------+-------+-------+-----

|Samples.| Max. | Min. | Avg. | Max. | Min. | Avg.

-----------------+--------+------+------+-------+-------+-------+-----

| p.c. | p.c. | p.c. | p.c. | p.c. | p.c. | p.c.

König | 123 |35·12 | 5·50 | 14·49 |85·25 |76·37 |83·27

Bell | 117 |20·75 | 4·15 | 14·2 | .. | .. | ..

| | | | | | |

Hassall { | 48 |15·43 | 4·18 | .. |96·93 |67·72 | ..

{ | |28·6 | 8·48 | .. |96·93 |67·72 | ..

| | | | | | |

Angell and Hehner| 30 |16·0 | 6·4 | .. |90·2 |76·4 | ..

Wanklyn | 50 |24·9 | 8·6 | .. | .. | .. | ..

Caldwell | 26 |30·75 |10·45 | .. | .. | .. | ..

Ellis | 12 |10·5 | 4·9 | .. |89·7 |80·8 | ..

Larue | 12 |16·5 | 8·0 | .. |86·9 |79·14 | ..

| | | | | | |

Fleischman {fresh| .. | .. | .. | 18·0 | .. | .. |80·0

{salt | .. | .. | .. | 12·0 | .. | .. |83·5

| | | | | | |

Blyth | 5 |12·984| 8·58 | .. |87·223 |82·643 |85·45

Schacht | 8 | 9·00 | 1·25 | .. |98·00 |87·00 | ..

-----------------+--------+------+------+-------+-------+-------+-----

-----------------+----------------------+-----------------------

| Curd. | Salts.

Analyst. |-------+-------+------+--------+--------------

| Max. | Min. | Avg. | Max. | Min. | Avg.

-----------------+-------+-------+------+--------+-------+------

| p.c. | p.c. | p.c. | p.c. | p.c. | p.c.

| | | | | |

König | 4·77 | 0·25 | 1·29 | 5·65 | 0·08 | 0·95

Bell | 4·02 | .. | 1·2 | 15·08 | 0·5 | ..

| | | | | |

Hassall { | .. | .. | .. | 2·91 | 0·3 | ..

{ | .. | .. | .. | 8·24 | 1·53 | ..

| | | | | |

Angell and Hehner| 5·1 | 1·1 | .. | 8·5 | 0·4 | ..

Wanklyn | .. | .. | .. | 10·7 | 0·1 | ..

Caldwell | .. | .. | .. | .. | .. | ..

Ellis | 4·9 | 1·1 | .. | 6·2 | 0·1 | ..

Larue | 5·5 | 1·5 | .. | 3·60 | 0·4 | ..

| | | | | |

Fleischman {fresh| .. | .. | .. | .. | .. | 2·0

{salt | .. | .. | .. | .. | .. | 6·5

| | | | | |

Blyth | 5·137 | 2·054 | 2·5 | 3·151 | 0·424 | ..

Schacht | 0·5 | .. | .. | 6·0 | 0·57 | ..

-----------------+-------+-------+------+--------+-------+------

_Proximate Analysis._

About five grammes of the well-averaged sample are weighed out in a

tared platinum capsule, and dried for three hours (or until constant

weight is obtained) over a water-bath (or over a low flame, constantly

stirring with a thermometer), and the decrease in weight (water)

ascertained. As a rule, the proportion of water in genuine butter

varies from 8 to 16 per cent. The residue in the capsule is then

melted at a gentle heat, and the liquid fat cautiously poured off

from the remaining caseine and salt, these latter being afterwards

more completely exhausted by washing with ether. Upon now drying the

residue, the loss in weight will give the amount of fat present.

The caseine is next determined by the loss in weight obtained upon

incinerating the matters left undissolved by the ether, the remaining

inorganic matter being the salt contained.

The proportion of fat present in genuine butter ranges from 82 to 90

per cent.; it should never be below 80 per cent. The average amount of

caseine is 2·5 per cent.; greater proportions, frequently occurring

in unadulterated butter, render it more liable to become rancid. The

ash should consist of sodium chloride, with some calcium phosphate;

the amount of salt is quite variable, but it usually ranges from 2

to 7 per cent. The proportion of ingredients, not fat, in butter

may be conveniently determined by melting 10 grammes of the sample

in a graduated tube, provided with a scale at its lower end, which

is narrowed, adding 30 c.c. of petroleum naphtha, and shaking the

mixture. After standing a few hours, the non-fatty matters collect in

the lower portion of the tube, and their volume is read off. Genuine

butter is said to yield from 12 to 14 per cent. (assuming each c.c. to

equal one gramme), while adulterated specimens may show 20 per cent. of

matters not fat.

_Examination of the Butter-fat._

The most common and important sophistication of butter consists in the

addition of foreign fats, embracing both animal fats (oleomargarine and

lard) and vegetable oils (cotton-seed, olive, rape-seed, cocoa-nut,

almond, palm, etc.). Of these, oleomargarine is doubtless the most

often employed. Oleomargarine is the more fusible portion of beef fat,

and is prepared by straining the melted fat, allowing the oil thus

obtained to stand for some time at a temperature of about 24°, when

most of the stearine and palmitine will separate out, and cooling the

remaining oil until it solidifies. This is next churned with milk, a

little colouring matter (annato) being added, and the product is then

chilled by mixing it with ice; salt is now added, and the mass is

finally worked up into lumps.

It is stated that fifteen establishments in the United States are

engaged in the manufacture of oleomargarine, the annual production

in the State of New York alone being about 20,000,000 pounds. The

rapid increase in the manufacture of oleomargarine is shown by the

following statistics:--In 1880 this country exported 39,236,655

pounds of butter and 20,000,000 pounds of oleomargarine, while in

1885 the exportation of butter declined to 21,638,128 pounds, and

the exportation of oleomargarine reached nearly 38,000,000 pounds.

The present production is said to approximate 50,000,000 pounds per

annum. The most characteristic difference in the composition of genuine

butter and oleomargarine consists in the greater proportion of soluble

fats contained in the former. This is illustrated by the following

comparative analysis of the two products (Mége Mouriès):--

---------------+---------------+---------------

|Genuine Butter.|Oleomargarine.

---------------+---------------+---------------

| per cent. | per cent.

Water | 11·968 | 11·203

Solids | 88·032 | 88·797

+---------------+---------------

| 100·000 | 100·000

_Solids_: | |

Insoluble fats | 75·256 | 81·191

Soluble fats | 7·432 | 1·823

Caseine | 0·182 | 0·621

Salt | 5·162 | 5·162

+---------------+---------------

| 88·032 | 88·797

---------------+---------------+---------------

Lard is likewise occasionally used in the United States as an

admixture to butter, the product, “lardine,” being sold either as

oleomargarine-butter, or as the genuine article. Dr. Munsell mentions

a factory in New York city where the weekly output of larded butter is

5000 pounds. As a result of the efforts of the New York State Dairy

Commission, it has been estimated that the sale of imitation butter in

this State in 1885 suffered a decrease of about 60 per cent., although

the quantity manufactured in the United States showed an increase of 50

per cent.

The specific gravity and melting point of butter have been suggested as

criteria for its purity; in most cases, however, these determinations

possess a rather limited value; as already stated, butter fat, at the

temperature of 37°·7, has a density ranging from 0·91200 to 0·91400.

The relation between the specific gravity of a fat and the proportion

of insoluble acids contained was first noticed by Bell. This is shown

in the following table which refers to pure butter fat.

Specific Gravity | Per cent.

at 37°·7. | Insoluble Acids

0·91382 | 87·47

0·91346 | 87·89

0·91337 | 87·98

0·91290 | 88·48

0·91286 | 88·52

0·91276 | 88·62

0·91258 | 88·80

0·91246 | 89·00

The following results have been obtained by the analysis of samples of

various animal fats, and oleomargarine butter.

--------------------------+------------------+------------------

| Specific Gravity | Per cent. Fixed

| at 37°·5. | Fatty Acids.

--------------------------+------------------+------------------

Mutton suet | 0·90283 | 95·56

Beef suet | 0·90372 | 95·91

Fine lard | 0·90384 | 96·20

Dripping (commercial) | 0·90456 | 94·67

Mutton dripping (genuine) | 0·90397 | 95·48

Oleomargarine butter | 0·90384 | 94·34

„ „ | 0·90234 | 94·83

„ „ | 0·90315 | 95·04

„ „ | 0·90379 | 96·29

„ „ | 0·90136 | 95·60

--------------------------+------------------+----------------

It will be noticed that the fats mostly used to adulterate butter are

of a lower density. Blyth regards a gravity below 0·911 (at 37°·5) as

clearly pointing to the presence of foreign fatty admixture.

The specific gravity determination is made by means of the areometer,

or by the gravity bottle; numerous indirect methods have also been

proposed. P. Casamajor[26] suggests a process for distinguishing

genuine butter from oleomargarine which is based upon the fact that

the density of a liquid in which a body remains in equilibrium is the

density of the body itself. As the result of his investigations it was

found that pure butter at 15° would be held in equilibrium by alcohol

of 53·7 per cent. (sp. gr. = 0·926), and that oleomargarine would

remain in equilibrium, at the same temperature, in alcohol of 59·2 per

cent. (sp. gr. = 0·905). If equal volumes of alcohol of 53·7 per cent.

and 59·2 per cent. (_i.e._ an alcohol of 56·5 per cent.) are taken,

and a drop of melted butter and of oleomargarine are delivered upon

its surface, the former will sink to the bottom and the latter will

remain at the top, so long as the two globules are warm and liquid.

In case the temperature of the alcohol is about 30°, the butter will

solidify and also rise to the top, whereas the oleomargarine may remain

liquid. On now keeping the alcohol for a short time at a temperature

of 15° the oleomargarine becomes opaque, but remains at the top, while

the solidified butter will sink to the bottom. If alcohol of 59·2 per

cent. is employed, oleomargarine will remain at the surface and genuine

butter fall to the bottom at all temperatures above 15°, and at this

temperature oleomargarine will be in equilibrium. Since not over 33 per

cent. of butter is usually added to oleomargarine, it is proposed to

use alcohol of 55 per cent., and consider as oleomargarine any sample

which does not sink at 15°.

The foregoing method can be applied quantitatively by determining the

strength of the alcohol which will keep in equilibrium a drop of the

fat under examination. Since the difference between 59·2 and 53·7

is 5·5, the difference between the strength of the alcohol used and

53·7, divided by 5·5 (or multiplied by 0·18), will give the proportion

of oleomargarine present. For example, if the globule is held in

equilibrium at 15° in 57 per cent. alcohol, the sample contains about

60 per cent. of oleomargarine, for (57 - 53·7) × 0·18 = 3·3 × 0·18 =

0·594 or, say, 6/10.

The melting-point of butter is below that of most of its fatty

adulterants; as previously stated, it varies from 28° to 37°. The

determination is made either in the ordinary manner by means of a

fine tube, or a little of the chilled sample is attached to a looped

platinum wire, placed near the thermometer-bulb, in water which is

gradually heated until fusion takes place. Blyth gives the following

table of the melting-points of various fats:--

°

Butterine 31·3

Cocoa butter 34·9

Butter (average) 35·8

Beef dripping 43·8

Veal dripping 47·7

Mixed 42·6

Lard, from 42 to 45

Ox fat, from about 48 „ 53

Mutton fat, from about 50 „ 51

Tallow 53·3

Numerous qualitative tests have been proposed by various authorities

for the detection of foreign fats in butter, of which the following are

perhaps sometimes of use. It should be added that the value of these

tests, when applied to mixtures, is limited and very uncertain.

1. A little of the sample is heated in a test-tube: pure butter froths

and acquires a brownish colour; with foreign fats there is but little

foaming, and, although the caseine present darkens, the liquid itself

remains comparatively clear.

2. If a sample containing oleomargarine is melted and the oil burned

in an ordinary lamp-wick, a decided odour of burning tallow will be

produced upon extinguishing the flame. Specimens of real butter,

however, have been found to also emit a tallow-like odour.

3. The melted sample is filtered and treated with boiling ether;

pure butter fat dissolves much more readily than do lard and tallow.

Upon adding methylic alcohol to the solution the latter fats are

precipitated, whereas pure butter will remain in solution.

4. If the filtered fat is distilled with a mixture of alcohol and

sulphuric acid, the distillate will possess the odour of butyric ether

_in a very marked degree_, in case it consists of butter.[27]

5. The strained fat is treated with a solution of carbolic acid (1 part

acid and 10 parts water): genuine butter dissolves to a clear solution;

beef, mutton, and swine fat form two layers, the upper one becoming

turbid upon cooling.

6. If the sample consists of butter or oleomargarine, and is mixed

with about ten parts of glycerine and the emulsion digested with a

mixture of equal parts of ether and alcohol, two layers of solution

will be produced, without any deposit of solid matter between them;

if, however, lard, suet, or starch is present it will become deposited

between the layers.

It has already been mentioned that butter differs from some of its

fatty adulterants in containing a considerable proportion of fatty

acids which are soluble in hot water, the acids present in most

foreign fats being, on the other hand, almost entirely insoluble. The

estimation of the relative amounts of soluble and insoluble acids

contained in a fat possesses therefore much importance; indeed, more

significance attaches to this determination than to any other. The

processes most frequently employed in the quantitative examination of

butter fat are those of Koettstorfer, Hehner, and Reichert.

Koettstorfer’s method[28] is based upon the fact that, as butter fat

contains the fatty acids, having a smaller molecular weight than those

present in other fats, it must contain more molecules of acid, and will

therefore require a greater amount of an alkali to effect saponication.

The process is executed as follows:--One or two grammes of the filtered

fat are weighed out in a narrow beaker and heated over a water-bath

with about 25 c.c. of one-half normal alcoholic solution of potassium

hydroxide. The saponification of the fat is assisted by repeated

stirring; when it is completed the beaker is removed from the bath,

a few drops of alcoholic phenol-phthaleine added for an indicator,

and the excess of potash used titrated back with one-half normal

hydrochloric acid. It has been found that pure butter fat requires from

221·4 to 232·4 milligrammes of potassium hydroxide for saponification.

The following are the number of milligrammes of alkali necessary for

the saponification of one gramme of various other fats:--

mgr.

Olive oil 191·8

Rape-seed oil 178·7

Oleomargarine 195·5

Beef tallow 196·5

Lard 195·5

Mutton suet 197·0

Dripping 197·0

Taking 227 milligrammes as the average amount of potassium hydroxide

required to saponify one gramme of pure butter fat, the following

formula has been suggested for the estimation of the proportion of

admixture in a suspected sample:--

(227 - _n_) × 3·17 = _x_,

in which _n_ represents the number of milligrammes of potassium

hydroxide used, and _x_ the percentage of foreign fat added. In the

Paris Municipal Laboratory, 221 milligrammes of K(OH) are regarded as a

standard for the saponification of one gramme of genuine butter.

Cocoa-nut oil, unfortunately, requires a figure (250 mgr.) considerably

above that of butter, and it is quite possible to prepare a mixture

of this oil and oleomargarine, that by the foregoing test would show

a result almost identical with that afforded by pure butter. Hehner’s

process,[29] which is often employed for the determination of the

insoluble fatty acids, is as follows:--About 4 grammes of the melted

and strained sample are dissolved in 50 c.c. of alcohol, containing two

grammes of potassium hydroxide in solution, and the mixture is heated

until complete saponification takes place. The alcohol is removed by

evaporation, the residue dissolved in 200 c.c. of water, and the fatty

acids precipitated by adding dilute sulphuric acid to distinct acid

reaction. The fatty acids are next melted by heating the liquid and are

then allowed to cool, after which the insoluble acids are poured upon

a tared filter and repeatedly washed with hot water until the washings

cease to show acidity. The filter and contents are finally cautiously

dried and weighed. In genuine butter the proportion of insoluble fatty

acids ranges between 86·5 and 87·5 per cent.; it should not be above

88 per cent.[30] Oleomargarine, lard, mutton, beef, and poppy, palm,

olive, and almond oils contain about 95·5 per cent. of insoluble

acids.[31]

The preceding process is also imperfect in not effecting the detection

of cocoa-nut oil, which affords only about 86 per cent. of insoluble

fatty acids, and although the presence of any considerable proportion

of this oil in butter would probably be indicated by the decreased

melting point of the admixture, an estimation of the soluble fatty

acids is by far the most reliable means for its detection. For this

determination Reichert’s method[32] is eminently adapted. In this

process advantage is taken of the facts that the amount of soluble

acids in a mixture of fat bears a direct relation to the proportion

of genuine butter present, and that, if the aqueous solution of a

saponified fat is decomposed by an acid and heated to boiling, the

greater portion of the soluble acids escape with the watery vapours and

can be collected and determined in the distillate. The details of this

method are essentially as follows:--2½ grammes of the filtered sample

are introduced into an Erlenmayer flask together with 1 gramme of

potassium hydroxide and 20 c.c. of dilute (80 per cent.) alcohol, and

the mixture is heated over the water-bath until complete saponification

is effected, and the alcohol _entirely_ removed. The soap thus formed

is dissolved in 50 c.c. of water, and decomposed by adding 20 c.c.

of dilute sulphuric acid (1:10). The flask is next connected with a

Liebig’s condenser and the contents carefully distilled until 50 c.c.

have passed over. The distillate is now freed from any insoluble acids

possibly present by filtration; it is then titrated with decinormal

soda solution, a few drops of litmus solution being employed as an

indicator. As the result of numerous tests, it has been found that

genuine butter, when examined by the above method, requires from 13 to

15 c.c. of the decinormal solution. The following are the number of

c.c. required by various other fats:--

Lard 0·2

Rape oil 0·25

Kidney fat 0·25

Olive oil 0·3

Sesamé oil 0·35

Oleomargarine 0·7 to 1·3

Cocoa-nut oil 3·70

Dr. Elwyn Waller[33] modifies the foregoing method of procedure by

adding 50 c.c. of water to the contents of the flask remaining after

the first distillation, and again distilling off 50 c.c., the process

being repeated until the final distillate neutralises only 0·1 c.c. of

the decinormal alkali. With butter fat, it was found that the first

distillate contained about 79 per cent. of the total volatile acids

present. By means of this modification, a distinction between the

rate of distillation of the volatile fatty acids of different fats is

possible. The non-volatile acids left in the flask are washed several

times with water, in order to remove the glycerine and potassium

sulphate present, and are then dried and weighed.

For estimating the percentage of pure butter fat in a sample of mixed

fat, Reichert employed the formula: B = 7·3 (_m_ - 0·3), in which _m_

is the number of c.c. of soda solution used in the titration.

Baron Hübl[34] has recently suggested a method for butter testing,

which is founded upon the fact that the three series of fats (acetic,

acrylic, and tetrolic), unite in different proportions with the

halogens (iodine, bromine, and chlorine), to form addition products.

Iodine has been found especially well adapted to the examination of

fats. The standard solution employed is prepared by dissolving 25

grammes of iodine in 500 c.c. of 95 per cent. alcohol, and adding to

the solution a solution of 30 grammes of mercuric chloride in 500 c.c.

of alcohol. The reagent is then standardised by means of a solution

of 24 grammes of sodium hyposulphite in 1 litre of water. The test

is applied as follows:--1 gramme of the sample under examination is

introduced into a flask and dissolved in 10 c.c. of pure chloroform.

The iodine reagent is then gradually added from a burette, the mixture

being well shaken, until the coloration produced indicates that an

excess is present, even after standing for about two hours; 15 c.c.

of a 10 per cent. potassium iodide solution and 150 c.c. of water are

then added and the excess of iodine present determined by means of the

sodium hyposulphite solution, and deducted from the total quantity

used. The amount of iodine (in grammes) absorbed is calculated to 100

grammes of the fat; this is termed the iodine number. The examination

of numerous samples of genuine butter and oleomargarine, and other

fats, made at the laboratory of the New York State Dairy Commissioner,

furnished the following results:[35]--

Iodine Number.

Genuine butter from 30·5 to 43·0

Oleomargarine „ 50·9 „ 54·9

Cocoa-nut oil 6·8

Lard 55·0

Mutton fat 57·3

Oleine 82·3

Olive oil 83·0

Pea-nut oil 96·0

Sweet-almond oil 102·0

Cotton-seed oil 108·0

Poppy oil 134·0

It has been proposed to differentiate between butter and oleomargarine

by a determination of the proportion of glycerine contained.

Liebschütz[36] employs the following process for this estimation: 10

grammes of the sample are saponified by heating with 20 grammes of

barium hydroxide, until the water of crystallisation has been almost

entirely expelled. Alcohol is then added with constant stirring;

saponification quickly takes place, and is completed by evaporating

the mass nearly to dryness. The glycerine is extracted with boiling

water, the solution filtered, and the barium contained removed by

means of sulphuric acid. The filtrate from the barium sulphate is then

concentrated by evaporation, and the excess of sulphuric acid present

neutralised by adding a little barium carbonate. The filtered liquid

is now again evaporated to a small volume, and most of the salts

present precipitated by addition of absolute alcohol. After filtration

the alcoholic solution is evaporated over the water-bath, then dried

at 100° until constant weight is obtained. It is finally ignited and

the proportion of glycerine contained estimated by the loss in weight

sustained. This process is certainly far from being exact, owing

principally to the volatilisation of glycerine that occurs in the

evaporation of its aqueous and even alcoholic solutions. The following

results were obtained upon treating genuine butter and oleomargarine

according to the above method:--

Per cent. Glycerine.

Butter 3·75

Oleomargarine 7·00

Gelatine is said to have lately been used as an adulterant of butter,

more especially of artificial butter. Its detection is a matter of some

difficulty. The following method has been suggested. A considerable

quantity of the suspected butter is boiled with water, the solution

strained, a drop of acetic acid and a little potassium ferrocyanide

added, and the liquid boiled until the precipitate formed becomes

bluish in colour. The solution is then filtered hot and the filtrate

examined for gelatine by adding tannic acid to, or conducting chlorine

gas through it.

A sample lately imported under the name of “butter preservative” was

found by the author to consist of a dilute solution of phosphoric acid.

The use of this agent does not, however, appear to be prevalent to any

great extent.[37]

_Artificial Colouring._--The list of colouring matters said to be

added to butter includes the vegetable dyes, annato, carotin, fustic,

turmeric, marigold, and saffron; the coal-tar colour, Victoria

yellow (potassium dinitrocresylate), and Martius yellow (potassium

dinitronaphthalate), and the mineral pigment chrome yellow (plumbic

chromate). Of the foregoing, annato and carrot colour appear to be most

commonly employed. Mr. Edward W. Martin[38] has proposed a method for

the isolation of the former which consists in dissolving the butter in

carbon disulphide, and shaking the solution with a _dilute_ solution

of potassium hydroxide, in which the colouring matter dissolves; it

is subsequently identified by further tests. According to Mr. R. W.

Moore,[39] the presence of carotin in butter may be detected by first

agitating the carbon disulphide solution of the fat with alcohol, which

fails to extract this colour. Upon now adding to the mixture a drop

of dilute ferric chloride solution, again shaking the liquid and then

putting it aside for a short time, the alcoholic solution dissolves the

carrot colour, and if no other colouring matter is contained in the

butter, leaves the carbon disulphide colourless.

The artificially coloured butter may be dissolved in alcohol and tested

with the following reagents:--

(_a_) Nitric acid: greenish coloration, _saffron_.

(_b_) Sugar solution and hydrochloric acid: red coloration, _saffron_.

(_c_) Ammonia: brownish coloration, _turmeric_.

(_d_) Silver nitrate: blackish coloration, _marigold_.

(_e_) Evaporate the alcoholic solution to dryness and add concentrated

sulphuric acid: greenish-blue coloration, annato; blue coloration,

_saffron_.

(_f_) Hydrochloric acid: decolorisation, with formation of yellow

crystalline precipitate, _Victoria or Martius yellow_.

(_g_) Separation of a heavy and insoluble yellow powder, _chrome

yellow_ (see p. 130).

_Microscopic Examination._--The microscopic examination of butter has

lately received considerable attention as a means for the detection

of the presence of foreign fats. Genuine butter generally exhibits

under the microscope a crowded mass of globules of fat, fatty crystals

being commonly absent. In oleomargarine a more crystalline structure

is observed, with pear-shaped masses of fat and but few globules.

While the presence of crystals in a sample may justly be regarded as

suspicious, it is by no means a positive evidence of adulteration,

since, under certain circumstances, pure butter may present the same

indications. In applying the microscopic test, a small portion of the

fat is made into a thin layer on the slide, and then protected with a

glass cover, applied with rather gentle pressure.

Plate VI.[40] represents the microscopic appearance of genuine

butter and oleomargarine. It will be observed that in butter (Fig.

1) numerous globules but no crystals of fat are presented, the

crystals present being those of salt. In oleomargarine (Fig. 2) the

distinctive pear-shaped masses of fat, accompanied by only a small

number of fatty globules, are to be seen. Dr. Thomas Taylor (of the

U.S. Department of Agriculture), has made an elaborate investigation

of the microscopic appearance of various fats when viewed by polarised

light. He regards the presence of peculiar globular crystals and the

black cross commonly termed St. Andrew’s cross as characteristic of

genuine butter.[41] Lard, beef, and other fats are said to exhibit

different and, to some extent, distinctive crystalline forms. Prof.

Weber,[42] however, affirms that mixtures of lard and tallow fat,

under certain conditions, cannot be distinguished from butter by means

of this method of examination. More recently, Dr. Taylor states that

the distinguishing difference between butter and other fats under the

microscope is that the former, when observed by polarised light through

a selenite, exhibits a uniform tint, whereas the latter shows prismatic

colours. Although the results of these investigations cannot as yet be

considered as perfectly satisfactory or conclusive, they certainly are

entitled to rank as a highly valuable and important step in advance of

the optical processes hitherto employed.

PLATE VI.

[Illustration: Fig. 1, Butter × 400.]

[Illustration: Fig. 2, Oleomargarine × 400.]

ARTOTYPE. E. BIERSTADT, N. Y.

PLATE VII.

[Illustration: Butter × 40.]

[Illustration: Butter × 40.]

[Illustration: Beef × 40.]

[Illustration: Lard × 160.]

[Illustration: Butterine × 40.]

[Illustration: Oleomargarine × 40.]

FAT CRYSTALS.

Plate VII. exhibits the appearance of butter, oleomargarine, beef, and

some other fats, when viewed by the microscope and polarised light. It

will be noticed that, while a discrimination between lard and butter is

readily made, oleomargarine presents the St. Andrew’s cross, stated to

be characteristic of genuine butter. These photomicrographs represent

the results of investigations made in the Chemical Division of the U.S.

Department of Agriculture.

The question of the sanitary effects of oleomargarine and other

substitutes for butter, has been studied by many scientists, and with

very discordant results. Doubtless the great divergence of opinion

which at present exists, is largely due to the fact that the artificial

products examined have been made according to different processes,

and with varying regard to the quality of the fats used in their

manufacture, and to the degree of care and cleanliness observed. The

attention of the American public has very lately been directed to the

oleomargarine question, by the recent enactment of a national law

imposing a tax upon the manufacture of the article.

Without entering to any great extent into the subject of the

wholesomeness of artificial butter as it is generally met with in

commerce, it will be of interest to refer to the conclusions reached by

two or three sanitarians who have devoted particular attention to this

aspect of the question. Prof. W. O. Atwater[43] summarises the results

of his investigation of oleomargarine as follows:--

“1. The common kinds of imitation butter, oleomargarine, butterine,

etc., when properly made, agree very closely in chemical composition,

digestibility, and nutritive value with butter from cow’s milk.

“2. In fulfilling one of the most important functions of food, namely,

that of supplying the body with heat and muscular energy, they, with

butter, excel in efficiency all, or nearly all, our other common food

materials.

“3. Considering the low cost at which they can be produced, as well

as their palatability and nutritive value, they form a food product

of very great economical importance, and one which is calculated to

greatly benefit a large class of our population whose limited incomes

make good dairy butter a luxury.

“4. Imitation butter, like many other manufactured food materials,

is liable (but in actual commerce has been found not to be so) to be

rendered unwholesome by improper materials and methods of manufacture.

It is also open to the especial objection that it is largely sold as

genuine butter. The interests of the public, therefore, demand that

it should be subjected to competent official inspection, and that it

should be sold for what it is, and not as genuine butter.”

Dr. S. B. Sharples[44] states: “When well made, it (oleomargarine) is

a very fair imitation of genuine butter; being inferior to the best

butter, but much superior to the low grades of butter too commonly

found in the market. So far as its influence on health is concerned,

I can see no objection to its use. Its sale as genuine butter is a

commercial fraud, and as such, very properly condemned by the law. As

to its prohibition by law, the same law which prohibited it should also

prohibit the sale of lard and tallow, and more especially all low-grade

butters, which are far more injurious to health than a good sweet

article of oleomargarine. A good deal has been said in regard to the

poor grade of fats from which the oleomargarine is made. Any one making

such assertions in regard to the fats is simply ignorant of the whole

subject. When a fat has become in the least tainted, it can no longer

be used for this purpose, as it is impossible to remove the odour from

the fat after it has once acquired it.”

_Per contra_, Dr. R. B. Clark, in an exhaustive report on butter,[45]

affirms with great decision, that artificial butter is not a wholesome

article of food, for the following reasons:--

“1. On account of its indigestibility.

“2. On account of its insolubility when made from animal fats.

“3. On account of its liability to carry germs of disease into the

human system.

“4. On account of the probability of its containing, when made under

certain patents, unhealthy ingredients.”

The two last grounds for condemning oleomargarine are evidently

affected by, and, in fact, dependent upon the character of the fat and

the exercise of care employed in its manufacture. In regard to the

relative digestibility of butter and its imitations, actual experiments

have been made by several chemists. A. Mayer,[46] from the results of

feeding human beings for three days on butter and on oleomargarine,

found that 1·6 per cent. less of the latter was absorbed by the system

than of the former, and inclines to the opinion, that with healthy

persons this proportion is so inconsiderable, that it is of little or

no importance. Dr. Clark considers these experiments of too limited

duration to be regarded as conclusive, although, so far as they went,

the results reached coincided with those obtained by him by a more

exhaustive investigation. Dr. Clark has made an examination of the

artificial digestion of butter as compared with oleomargarine and

other fats, including beef and mutton suet, and lard, cotton-seed,

sesamé, and cod-liver oils. The method of examination pursued was as

follows:--About 2 grammes of the melted fat was added to a digestive

fluid consisting of 0·33 gramme of “extractum pancreatis,” and 0·33

gramme of sodium bicarbonate, dissolved in 10 c.c. of distilled

water. This mixture was introduced into a test-tube, well shaken, and

then exposed to a temperature of 40°. The contents of the test-tube

were microscopically examined at the lapse of intervals of one,

four, and twelve hours. It was found from these tests that cod-liver

oil exhibited the most perfect state of emulsion, after which came

genuine butter, next lard oil, and then commercial “oleo.” Plate VIII.

represents the results obtained from the experiments made with butter

and commercial oleomargarine, as presented at the end of one, four,

and twelve hours. The globules of butter-fat, it will be observed, are

smaller in size and more uniform in appearance. Dr. Clark likewise

instituted experiments which tended to demonstrate the relative

insolubility of the fats used in the preparation of artificial butter.

PLATE VIII.

[Illustration: Butter 1 hour × 250.]

[Illustration: Oleomargarine 1 hour × 250.]

[Illustration: Butter 4 hours × 250.]

[Illustration: Oleomargarine 4 hours × 250.]

[Illustration: Butter 12 hours × 250.]

[Illustration: Oleomargarine 12 hours × 250.]

ARTIFICIAL DIGESTION OF FATS.

FOOTNOTES:

[26] Journ. Amer. Chem. Soc., iii. p. 83.

[27] The proportion of butyrine present in commercial oleomargarine

is often sufficient in quantity to cause the characteristic odour of

butyric ether to a noticeable degree.

[28] Fresenius’ ‘Zeitschrift,’ 1879, p. 197.

[29] ‘Zeitschrift für Analytische Chemie,’ 1877, p. 145.

[30] The French standard is 87·50 per cent.

[31] The percentage of foreign fat (F) in a sample can be calculated by

the formula F = (I - 88) × 13·3, in which I = the insoluble fatty acids.

[32] Fresenius’ Zeitschrift, 1879, p. 68.

[33] Journ. Amer. Chem. Soc., viii. p. 6.

[34] Dingl. Polyt. Journ., ccliii., p. 281.

[35] R. W. Moore notes that a certain mixture of lard and cocoa-nut

oil would give an iodine number identical with that of butter

fat.--(‘Analyst,’ x. p. 224.)

[36] Journ. Amer. Chem. Soc., vii. p. 134.

[37] Samples invoiced as “butter flavouring,” and consisting of butyric

acid, have also been imported.

[38] ‘Analyst,’ x. p. 163.

[39] Ibid., xi. p. 163.

[40] The author is indebted to Mr. Edward W. Martin for the negatives

used in the preparation of these and other photomicrographs of fats.

[41] _Vide_ ‘Proceedings of the American Microscopical Society,’ May

1885.

[42] ‘Bulletin of the Ohio Agricultural Experiment Station,’ March 1st,

1886.

[43] Bradstreet’s, June 19, 1886.

[44] Fourth Annual Report (1883) Mass. State Board of Health, p. 30.

[45] Second Annual Report of the New York State Dairy Commissioner, pp.

291-392.

[46] ‘Landwirthschaftliche Versuchsstation,’ ii. p. 215.

CHEESE.

Cheese consists essentially of the caseine and albumen of milk,

together with water, fat, lactic acid, and mineral salts. It is

prepared by the coagulation of milk by means of rennet, and is usually

obtained from cow’s milk (either fresh, skimmed, or sour), although

the milk of the goat, ewe, and other animals is occasionally used.

Its colour is very often due to the addition of annato. The following

table exhibits the composition of the best-known varieties of cheese,

according to the analysis of various chemists:--

----------------+----------+----------+-----------+---------+---------

| | | Caseine | |

| | | or | | Free

Variety. | Water. | Fat. |Nitrogenous| Milk | Acid, as

| | | Matter. | Sugar. | Lactic.

----------------+----------+----------+-----------+---------+---------

|per cent. |per cent. | per cent. |per cent.|per cent.

American (pale) | 31·55 | 35·93 | 28·83 | .. | 0·27

American (red) | 28·63 | 38·24 | 29·64 | .. | ..

Cheddar | 35·60 | 31·57 | 28·16 | .. | 0·45

Stilton | 23·57 | 39·13 | 32·55 | .. | 1·24

Gloucester | 35·75 | 28·35 | 31·10 | .. | 0·31

Dutch | 41·30 | 22·78 | 28·25 | .. | 0·57

Roquefort | 32·26 | 34·38 | 27·16 | .. | 1·32

Brie | 51·87 | 24·83 | 19·00 | .. | ..

Cheshire | 37·11 | 30·68 | 26·93 | .. | 0·86

Gruyère | 33·66 | 30·69 | 30·67 | .. | 0·27

Gorgonzola | 31·85 | 34·34 | 27·88 | .. | 1·35

Neufchatel | 37·87 | 41·30 | 17·43 | |

| | | | \ /

Camembert | 51·30 | .. | 19·00 | 3·50

| | | | / \

Parmesan | 27·56 | 15·95 | 44·08 | 6·69

----------------+----------+----------+-----------+-------------------

----------------+---------+---------------------

| | Composition of Fat.

| +----------+----------

Variety. | Ash. | Soluble | Insoluble

| | Acids. | Acids.

----------------+---------+----------+----------

|per cent.|per cent. | per cent.

American (pale) | 3·42 | 4·81 | 88·49

American (red) | 3·49 | 4·26 | 89·06

Cheddar | 4·22 | 4·55 | 88·75

Stilton | 3·51 | 4·42 | 88·76

Gloucester | 4·49 | 6·68 | 86·89

Dutch | 7·10 | 5·84 | 87·58

Roquefort | 4·88 | 4·91 | 88·70

Roquefort | 5·00 | .. | ..

Brie | 4·42 | 5·55 | 87·76

Cheshire | 4·71 | 4·41 | 88·97

Gruyère | 4·58 | 4·40 | 89·18

Gorgonzola | 3·40 | .. | ..

Neufchatel | | |

Camembert | 4·70 | .. | ..

| | |

Parmesan | 5·72 | .. | ..

----------------+---------+----------+----------

Dr. Muter has published the following analyses of cheese:--[47]

-----------------+----------------------------------------------------

|Insoluble Acids.

| +----------------------------------------------

| |Soluble Acids.

| | +-----------------------------------------

| | |Milligrammes K(OH) to saponify 1 gr.

| | | +-----------------------------------

| | | |Water.

| | | | +-----------------------------

| | | | |Fat.

| | | | | +-----------------------

Variety. | | | | | |Lactic Acid.

| | | | | | +-----------------

| | | | | | |Insoluble Ash.

| | | | | | | +-----------

| | | | | | | |Soluble

| | | | | | | | Ash.+-----

| | | | | | | | |Salt.

-----------------+-----+----+-----+-----+-----+-----+-----+-----+-----

Double Gloucester|87·00|6·28|229·3|37·20|22·80|1·80 |2·56 |2·00 |1·64

Stilton |86·20|7·02|231·7|28·60|30·70|1·08 |1·80 |2·22 |0·75

English cream |90·01|3·26|220·0|63·64|15·14|0·90 |0·72 |0·20 |0·12

Dutch |87·20|6·09|228·7|42·72|16·30|1·35 |2·26 |9·10 |4·02

Gruyère |87·32|5·98|228·0|33·20|27·26|1·35 |3·12 |1·58 |1·05

Rochefort |87·00|6·27|229·3|21·56|35·96|0·72 |1·70 |8·54 |3·42

Camembert |87·15|6·09|229·0|48·78|21·35|0·36 |0·16 |8·64 |3·46

Bondon |7·834|5·95|228·0|55·20|20·80|0·90 |0·52 |6·46 |3·16

American Cheddar |89·08|3·30|220·2|29·70|30·70|0·90 |2·16 |1·54 |1·20

Cheddar |87·66|5·00|227·5|33·40|26·60|1·53 |2·30 |2·00 |1·52

-----------------+-----+----+-----+-----+-----+-----+-----+-----+-----

According to this chemist, one gramme of genuine cheese should require

not less than 220 milligrammes K(OH) for saponification, as executed in

Koettstorfer’s process (see p. 71).

The following results were obtained by Griffiths[48] from the analysis

of American cheese, and by Gerber[49] from the analysis of artificial

American cheese:--

--------------+---------+------------+--------------

| American|Lard Cheese.|Oleomargarine

| Cheese.| | Cheese.

--------------+---------+------------+--------------

|per cent.| per cent. | per cent.

| | |

Water | 26·55 | 38·26 | 37·99

Fat | 35·58 | 21·07 | 23·70

Caseine, etc. | 33·85 | 35·55 | 34·65

Ash | 3·90 | 5·12 | 3·66

--------------+---------+------------+--------------

The constituents of cheese are very similar to those of milk; the

relations between the soluble and insoluble fatty acids is much the

same as in butter. In cheese, however, the milk-sugar is largely

decomposed into lactic acid, alcohol, and carbonic acid, during the

process of ripening or curing employed in its manufacture.

Another essential change effected by the curing of cheese is the

partial decomposition of the caseine into ammonia, which combines

with the unaltered caseine, forming soluble ammonium caseates. Other

products of the ripening process, also due to the decomposition of the

caseine, are tyrosine and leucine (C_{6}H_{13}NO_{2}). The butter-fats

are likewise transformed into the corresponding fatty acids, which give

rise to the formation of either the ammonia salts, acid albuminates, or

amines, such as butylamine or amylamine.

The characteristic odour of many varieties of cheese is chiefly owing

to the genesis of these latter compounds.

As with butter, the most important adulteration of cheese consists

in the addition of foreign fats. Doubtless, the most frequent

sophistication is the admixture of lard. Lard cheese (which is usually

sold as “Neufchatel”) is made by first preparing an emulsion of lard

and skimmed milk (in the proportion of one part of the former to two

parts of the latter). This is subsequently incorporated with skimmed

milk and butter-milk, the coagulation of the fat being then effected

in the usual manner. In regard to the production of this species of

cheese, it is stated that in the 23 factories in the State of New

York, the product of six months’ working (ending November, 1881), was

about 800,000 pounds, of which the greater proportion was exported.

The recent (1885) adoption of a New York State brand for “pure cream

cheese” has had a very good effect, and accomplished much in the

restriction of the manufacture and sale of the spurious article.

Another variety of imitation cheese, know as “anti-huff cheese,”

is prepared from skimmed milk without the addition of foreign fat,

but with the aid of various chemical preparations, such as caustic

or carbonated soda, saltpetre, and borax. The rind of cheese is

occasionally contaminated with poisonous metallic salts, including

those of lead, mercury, antimony, arsenic, copper and zinc, which are

added either for colouring purposes or to prevent the attacks of flies

and other insects. This form of adulteration is doubtless of rare

occurrence. The methods used in cheese analysis are much the same as

those employed in the examination of butter. The fat is determined

by exhaustion with ether (or preferably, petroleum naphtha), and

evaporation, the remaining solids not fat being likewise dried and

weighed. The difference between the combined weight of the fat and the

solids not fat, and the amount of the sample taken, represents the

proportion of water present. Lactic acid, while insoluble in petroleum

naphtha, is also dissolved by ether, and can be estimated by digesting

another portion of the sample with water, and titrating the filtered

liquid with decinormal soda solution. Its weight is then to be deducted

from the amount of fat previously obtained, in case ether was employed

in this determination. The relative proportions of the soluble and

insoluble fatty acids contained in cheese possess the same significance

in indicating the presence of oleomargarine and other foreign fats as

with butter; and they are determined by the same methods.

The examination of the colouring matter of cheese can be made by first

neutralising the free lactic acid, separating the fat by agitation

with water, filtering and drying; the fat is then tested with carbon

disulphide and potassium hydroxide (see p. 77).

FOOTNOTES:

[47] ‘Analyst,’ Jan. 1885, p. 3.

[48] Chem. News, pp. 47, 85.

[49] Dingl., vol. i. pp. 247, 474.

FLOUR AND BREAD.

Wheat (_Triticum vulgare_) forms the principal bread-stuff of civilized

nations, and is by far the most important of all cereal grasses. It

has one or more slender, erect and smooth stalks, which, owing to the

large proportion of siliceous matter present, possesses the strength

necessary for the support of the ears. The grain is imbricated in four

rows. The following are the averages of the results obtained by the

analyses of 260 samples of American wheat, made by the United States

Department of Agriculture, in 1883:--

Per cent.

Water 10·27

Ash 1·84

Oil 2·16

Carbohydrates 71·98

Fibrin 1·80

Albuminoids 11·95

Nitrogen 1·91

Analyses of the ash of wheat by the same Department, furnished the

following results:--

----------------+---------+-------------------

| | Foreign.

| Dakota. +---------+---------

| | Winter. | Spring.

----------------+---------+---------+---------

|Per cent.|Per cent.|Per cent.

Insoluble | 1·44 | 2·11 | 1·64

Phosphoric acid | 47·31 | 46·98 | 48·63

Potassa | 30·63 | 31·16 | 29·99

Magnesia | 16·09 | 11·97 | 12·09

Lime | 3·36 | 3·34 | 2·93

Soda | 1·17 | 2·25 | 1·93

Sulphuric acid | trace | 0·37 | 0·48

Chlorine | „ | 0·22 | 0·51

Ferric oxide | „ | 1·31 | 0·28

Undetermined | .. | 0·29 | 1·52

| ------ | ------ | ------

| 100·00 | 100·00 | 100·00

| | |

Total ash | 1·88 | 1·97 | 2·14

----------------+---------+---------+---------

FLOUR.

The name flour is usually given to the product obtained by grinding

wheat and removing the bran, or woody portion of the grain, by sifting

or bolting. Its constituents are starch, dextrine, cellulose, and sugar

(carbohydrates), the nitrogenous compounds albumen, gliadin, mucin,

fibrin, and cerealin, and fat, mineral substances and water. Upon

kneading flour with water, and removing the starch and soluble matters

by repeated washing, an adhesive body termed _gluten_ remains behind.

This is chiefly composed of gliadin, mucin, and fibrin.

According to Wanklyn,[50] the general composition of flour is:--

Per cent.

Water 16·5

Fat 1·5

Gluten 12·0

Modified starch 3·5

Vegetable albumen 1·0

Starch granules 64·8

Ash 0·7

The average of numerous analyses of American flour examined by the

Department of Agriculture gave:--

Per cent.

Water 11·67

Fat 1·25

Sugar 1·91

Dextrine 1·79

Starch 71·72

Soluble albuminoids 2·80

Insoluble „ 7·90

Total „ 10·70

Ash 0·54

The composition of the ash of flour from Minnesota wheat (1883), is as

follows:--

Per cent.

Insoluble 0·98

Phosphoric acid 49·63

Potassa 31·54

Magnesia 9·05

Lime 5·87

Soda 2·93

ANALYSIS OF FLOUR.

The following are the determinations generally required in the

proximate analysis of flour:--

_Water._--Two or three grammes of the sample are weighed in a tared

platinum dish, and heated in an air bath, until constant weight is

obtained. The proportion of water should not exceed 17 per cent.

_Starch._--A small amount of the flour is placed in a flask, connected

with an ascending Liebig’s condenser, and boiled for several hours with

water slightly acidulated with sulphuric acid. Any remaining excess

of acid is then neutralised with sodium hydroxide; the solution is

considerably diluted, and the glucose formed, estimated by means of

Fehling’s solution (see p. 111). 100 parts of glucose represent 90

parts of starch.

_Fat._--The inconsiderable proportion of fat in flour is best

determined by exhausting the dried sample with ether and evaporating

the solution.

_Gluten_ (albuminoids).--As previously stated, gluten is separated by

kneading the flour and repeated washing with water. After the removal

of the amylaceous and soluble ingredients, the residue is carefully

dried and weighed. A far more accurate method is to make a combustion

of a small portion of the flour with cupric oxide, and determine the

quantity of nitrogen obtained, the percentage of which, multiplied by

6·33, gives the percentage of gluten.[51] The proportion of gluten in

flour ranges from about 8 to 18 per cent. From 10 to 12 per cent, is

deemed necessary in order to make good bread, and, in England, any

deficiency in this constituent is remedied by the addition of bean or

other flour, but in the United States this practice is seldom required.

_Substances soluble in cold water._--About five grammes of the flour

are digested with 250 c.c. of cold water, and the solution filtered,

and evaporated to dryness. Good flour is stated to yield 4·7 per cent.

of extract when treated in this manner, the soluble matters consisting

of sugar, gum, dextrine, vegetable albumen, and potassium phosphate.

The latter salt, which constitutes about 0·4 per cent. of the extract,

should form the only mineral matter present.

_The Ash._--The ash of flour is determined in the usual manner, by

ignition in a platinum dish. It varies in amount from 0·3 to 0·8 per

cent., and should never exceed a proportion of 1·5 per cent.

When of good quality, wheaten flour is perfectly white, or has only a

faint tinge of yellow. It should be free from bran, and must not show

red, grey, or black specks, nor possess a disagreeable odour. It should

also exhibit a neutral reaction and a decided cohesiveness, acquiring

a peculiar soft and cushion-like condition when slightly compressed.

Formerly, wheaten flour was mixed with various foreign meals, such as

rye, corn, barley, peas, beans, rice, linseed, buckwheat, and potato

starch; but at present this form of adulteration is probably but

rarely resorted to, at least in the United States. The presence of

mildew, darnel, ergot, and other parasites of the grain, constitutes

an occasional contamination of flour. The most frequent admixture

consists, however, in the addition of alum, which, although more

extensively used in bread, is also employed in order to disguise the

presence of damaged flour in mixtures, or to improve the appearance of

an inferior grade; its addition to a damaged article serves to arrest

the decomposition of the gluten, thereby preventing the flour from

acquiring a dark colour, and disagreeable taste and odour.

It has recently been stated that in flour which has been kept for a

long time in sacks, a transformation of the gluten sometimes occurs,

resulting in the production of a poisonous alkaloid. This body may be

separated by evaporating the ethereal extract of the flour to dryness,

and treating the residue with water. The presence of the alkaloid in

the filtered aqueous solution is recognised by means of potassium

ferrocyanide. The presence of an excessive proportion of moisture is

doubtless instrumental in the formation of toxic alkaloids or fungi in

old flour and bread.

Pure wheaten flour is coloured yellow when treated with ammonium

hydroxide, whereas corn meal assumes a pale brown colour, and the meals

prepared from peas, beans, etc., become dark brown in colour when

tested in this way. Nitric acid imparts an orange-yellow colour to

wheaten flour, but fails to change the colour of potato-starch, with

which it forms a stiff and tenacious paste.

Potato-starch is readily detected by examining a thin layer of the

sample on a slide under the microscope, and adding a dilute solution

of potassium hydroxide, which, while not affecting the wheaten starch,

causes the potato-starch granules to swell up very considerably.

Leguminous starches, such as peas, etc., contain approximately 2·5 per

cent. of mineral matter; in pure flour, the average proportion of ash

is only about 0·7 per cent., and this difference is sometimes useful in

the detection of an admixture of the former.

The external envelope of the granules of potato-starch offers far less

resistance when triturated in a mortar than that of wheat, and upon

this fact a simple test for their detection is founded. It is executed

by rubbing up a mixture consisting of equal parts of the sample and

sand with water, diluting and filtering the paste formed, and then

adding to it a solution of 1 part of iodine in 20 parts of water. In

the absence of potato-starch, an evanescent pink colour is produced;

in case it is present, the colour obtained is dark purple, which in

time also disappears.

Among the methods which have been suggested for the detection of

such accidental impurities as darnel, ergot, and mildew, are the

following:--If pure flour is digested for some time with dilute

alcohol, the latter either remains quite clear or it acquires a very

light straw-colour; with flour contaminated with darnel, the alcohol

shows a decided greenish tint, and possesses an acrid and disagreeable

taste. In case the alcohol used is acidulated with about 5 per cent.

of hydrochloric acid, the extract obtained exhibits a purple-red

colour with flour containing mildew, and a blood-red colour with flour

containing ergot. When flour contaminated with ergot or other moulds,

is treated with a dilute solution of aniline violet, the dye is almost

wholly absorbed by the damaged granules, which are thus rendered more

noticeable in the microscopic examination.

The following test is often used for the detection of alum in flour:--A

small quantity of the suspected sample is made into a paste with a

little water and mixed with a few drops of an alcoholic tincture of

logwood; a little ammonium carbonate solution is then added. In the

presence of alum, a lavender-blue coloured lake is formed, which

often becomes more apparent upon allowing the mixture to remain at

rest for a few hours. The production of a brown or pink coloration is

an indication of the absence of alum. A modification of this test,

proposed by Blyth, consists in immersing for several hours in the cold

aqueous extract of the flour a strip of gelatine, with which the alum

combines; the gelatine is subsequently submitted to the action of the

logwood tincture and ammonium carbonate as above.

For the quantitative estimation of alum in flour, the following

processes are usually employed:--A considerable quantity of the sample

is incinerated in a platinum dish, the ash is boiled with dilute

hydrochloric acid and the solution filtered. The filtrate is next

boiled and added to a concentrated solution of pure sodium hydroxide,

the mixture being again boiled and afterwards filtered hot. A little

sodium diphosphate is now added to the filtrate which is then slightly

acidulated with hydrochloric acid, and finally made barely alkaline by

addition of ammonium hydroxide. The resulting precipitate, which, in

the presence of alum, consists of aluminium phosphate, is brought upon

a filter, well washed, and then weighed.

Another method, which is a modification of that of Dupré, is as

follows:--The ash obtained by the calcination of the flour (or bread),

is fused, together with four times its weight of pure mixed sodium and

potassium carbonates, the fused mass treated with hydrochloric acid,

the solution evaporated to dryness and the separated silica collected

and weighed. A few drops of sodium phosphate solution are added to

the filtrate from the silica, then ammonium hydroxide in excess, by

which the calcium, magnesium, ferric and aluminium phosphates are

precipitated. The two latter are next separated by boiling the liquid

with an excess of acetic acid (in which they are insoluble), and

brought upon a filter, washed, dried, and weighed. The iron sometimes

accompanying the precipitate of aluminium phosphate, can be determined

by reduction with zinc and titration with potassium permanganate.

If the presence of alum is indicated by the logwood test, and it is

quantitatively determined by either of the preceding methods, it has

been suggested that an allowance be made for the small proportion of

aluminium silicate occasionally found in unadulterated flour or bread,

and a deduction from the total alum present of one part of alum for

every part of silica obtained is considered proper. The weight of

aluminium phosphate found, multiplied by 3·873, or by 3·702, gives

respectively the corresponding amounts of potash-alum or ammonia-alum

contained in the sample examined.

BREAD.

Bread is usually prepared by mixing flour with water, kneading it into

a uniform dough, submitting it to a process of “raising,” either by

means of a ferment or by the direct incorporation of carbonic acid gas,

and finally baking the resulting mass.

Unleavened bread, however, is made by simply kneading flour with water,

with the addition of a little salt, and baking. The oatcake of the

Scotch, the passover bread of the Israelites, and the corncakes of the

Southern States are the best known varieties of unleavened bread.

The porosity peculiar to raised bread is caused by the generation of

a gas, either previous to, or during the process of baking. In former

times (and to some extent at present, notably in Paris), fermented

bread was made by the use of _leaven_, which is dough in a state of

incipient decomposition; but in this country, the common agent employed

in raising bread is yeast, which consists of minute vegetable cells

(_Torula cerevisiæ_) forming either the froth or deposit of fermenting

worts.

By the action of these ferments, the gluten of the flour first

undergoes a modification and enters into a peculiar combination with

the starch-granules, which become more or less ruptured; the soluble

albumen is rendered insoluble, and the starch is transformed, first

into sugar, then into carbonic acid and alcohol. These changes are

perfectly analogous to those which occur in the fermentation of the

wort in the preparation of fermented liquors.

Other and minor decompositions likewise occur, such as the partial

conversion of the starch into dextrine, the sugar into lactic acid,

and the alcohol into acetic acid, but the most essential change is the

production of alcohol and carbonic acid. The alcohol formed is mainly

volatilised, although an average proportion of 0·3 per cent. of this

compound has been found in samples of fresh bread. The escape of the

carbonic acid is retarded by the gluten, and to its expansion is due

the porous or spongy appearance of well-made bread.

Of late years, artificial substitutes for the fermentation process in

the production of porous bread have been extensively employed. By the

use of these agents, the liberation of carbonic acid in the dough is

accomplished and a slight gain of weight is effected, as none of the

original ingredients of the flour are lost by fermentation.

“Aërated bread” is made by kneading the flour under pressure with water

highly charged with carbonic acid gas, which, upon the removal of the

pressure, expands, and gives porosity to the bread. The use of “baking

powders” effects the same result in a more convenient manner, and is

largely practised in families. These compounds generally consist of

sodium bicarbonate (sometimes partially replaced by the corresponding

ammonia salt), and tartaric acid, or potassium bitartrate, together

with rice or other flour. A more commendable preparation is a mixture

of sodium bicarbonate with potassium or calcium acid phosphates, the

use of which is claimed to restore to the bread the phosphates lost by

the removal of the bran from the flour. Baking powders are often mixed

in the dry state with flour, and the produce, which is known under the

name of “self-raising flour,” only requires to be kneaded with water

and baked to form porous bread. However great the convenience attending

the use of these compounds, they are often open to the objection that

their decomposition gives rise to the formation of aperient salts,

_e.g._ sodium tartrate, and that they are very frequently contaminated

with alum.

As a result of the chemical changes which take place in the

fermentation of the flour and the subsequent application of heat, the

composition of bread differs materially from that of the grain from

which it is prepared. As already mentioned, the soluble albuminoids

are rendered insoluble, and the starch is partially transformed into

sugar (maltose). The unconverted starch is modified in its physical

condition, the ruptured granules being far more readily acted upon

by the digestive fluids than before. The proportion of soluble

carbohydrates is naturally augmented in bread. The amount of ash is

also somewhat increased, chiefly owing to the addition of salt, but

it should not exceed a proportion of 2 per cent. The quantity of

water in bread varies considerably. Wanklyn fixes 34 per cent. as the

standard; greater proportions have, however, been frequently found.

In ten samples of apparently normal bread, examined by E. S. Wood,

Analyst to the Massachusetts State Board of Health, the amounts of

moisture contained varied from 34 to 44 per cent. The quantity of

water decreases very rapidly upon exposure to the air. Thus, Clifford

Richardson[52] found that bread which showed 36 per cent. of moisture

when freshly baked, contained but 5·86 per cent. after drying for two

weeks. Stale bread would seem to contain water in a peculiar molecular

condition, and, as is well known, upon heating (“toasting”), it

reassumes the porous state.

According to analyses collected by König,[53] the mean composition of

bread is as follows:--

-------------+--------------------------------------------------------

|Water.

| +--------------------------------------------------

| |Nitrogenous substances.

| | +-----+------+-------------------------------

| | |Fat. |Sugar.| Extractive free from Nitrogen.

| | | | ++ +-----------+--------------

| | | | | |Cellulose. | Dry

| | | | | | +-----| Substances.

| | | | | | |Ash. |--------------

| | | | | | | |Carbohydrates.

| | | | | | | |-----+

| | | | | | | | N. |

-------------+-----+-----+-----+-----+-----+-----+-----+-----+--------

| per | per | per | per | per | per | per | per | per

|cent.|cent.|cent.|cent.|cent.|cent.|cent.|cent.| cent.

Fine wheat | | | | | | | | |

bread |31·51| 7·06| 0·46| 4·02|52·56|0·32 | 1·09| 1·75| 87·79

Coarse | | | | | | | | |

wheat bread|40·45| 6·15| 0·44| 2·08|49·04|0·62 | 1·22| 1·65| 85·84

Rye bread |42·27| 6·11| 0·43| 2·31|46·94|0·49 | 1·46| 1·69| 85·31

Pumpernickel |43·42| 7·59| 1·51| 3·25|41·87|0·94 | 1·42| 2·15| 79·74

-------------+-----+-----+-----+-----+-----+-----+-----+-----+--------

Clifford Richardson gives the following results of the analysis of

ordinary family loaf-bread:--

Per cent.

Water 37·30

Soluble albuminoids 1·19

Insoluble „ 6·85

Fat 0·60

Sugar 2·16

Dextrine 2·85

Starch 47·03

Fibre 0·85

Ash 1·17

------

100·00

Nitrogen 1·29

Total albuminoids 8·04

The analysis of bread is conducted essentially in the same manner

as that of flour. Under ordinary circumstances, the determinations

required are limited to an estimation of the moisture contained in

the crumb, the amount of the ash, and special tests for the presence

of alum and copper salts. Owing to the broken condition of the starch

granules in bread, their identification by the microscope is usually

rendered exceedingly difficult. The logwood test for alum in bread

is applied by Bell as follows:--About 10 grammes of the crumb are

immersed in a little water containing 5 c.c. each of the freshly

prepared logwood tincture and solution of ammonium carbonate for about

five minutes, after which the liquid is decanted, and the bread dried

at a gentle heat. In the presence of alum the bread will acquire

the characteristic lavender tint mentioned under Flour. It should

be added, that salts of magnesia also produce a lavender lake with

alum; but this fact does not affect the usefulness of the process as

a preliminary test to the quantitative determination of the mineral

impurities present in the sample under examination. The quantitative

examination of alum in bread is made by one of the methods described on

p. 93. Bread, free from alum, will sometimes yield 0·013 per cent. of

aluminium phosphate, and this amount should therefore be deducted from

the weight of the precipitate obtained.

The average of the results obtained by Dr. Edward G. Love, New York

State Board of Health, from the examination of the crumb of ten samples

of the cheaper varieties of wheaten bread were as follows:--

Per cent.

Water 42·80

Total ash 1·0066

Silica and sand 0·0056

Aluminium (and ferric) phosphates 0·0053

That the addition of alum to bread is prevalent seems to admit of

little doubt. The British Public Analysts, in 1879, tested 1287 samples

of bread, of which 95 (or 7·3 per cent.) contained alum. Of 18 samples

examined, in 1880, in the city of Washington, 8 were adulterated with

the salt. The question of the sanitary effects produced by the use of

alumed bread is one which has given rise to very extended discussion.

According to some authorities, the conversion of alum into an insoluble

salt by the fermentation process, which takes place in bread-making,

is regarded as a proof that it remains inert, and is consequently

harmless in its effects. Others contend that its action as a preventive

of excessive fermentation is at the expense of valuable nutritious

constituents of the flour, and that its combination with the phosphates

present in the grain results in the formation of an insoluble salt

which tends to retard digestion. Experiments have been made by J. West

Knights, on the comparative action of artificial gastric juice upon

pure and alumed bread, which apparently support this latter view.

Another objection to the use of alum is that it is frequently employed

for the purpose of disguising the bad quality of damaged and inferior

grades of flour. The presence of copper salts in bread is of rare

occurrence. Their detection is accomplished by treating a portion

of the crumb with a dilute solution of potassium ferrocyanide

acidulated with acetic acid, which, in presence of copper, will impart

a reddish-brown colour to the bread. If contained in any appreciable

proportion, it can be extracted from the ash obtained by the

incineration of the bread, and deposited upon the interior of a weighed

platinum capsule by the electrolytic method.

_Starch_ (C_{6}H_{10}O_{5}).--Starch, which enters so largely into the

composition of cereals, is a carbo-hydrate, _i. e._ hydrogen and oxygen

are contained in the proportions necessary to form water. In this

respect, it is identical with woody fibre, cellulose, and dextrine.

The well-known dark-blue colour produced upon the addition of a

solution of iodine to starch-paste forms the usual qualitative test

for its presence. This coloration is discharged by alkalies and by a

solution of sulphurous acid. The quantitative estimation of starch in

mixtures is best effected by heating the dry substance in a closed

tube for 24 hours, together with a dilute hot alcoholic solution of

potassium hydroxide. The hot liquid is next filtered, the residue

washed with alcohol, and the filtrate heated with 2 per cent. solution

of hydrochloric acid until it ceases to show the blue coloration when

tested with iodine. It is then rendered alkaline, and the proportion of

starch originally present, calculated from the amount of sugar formed,

as determined by Fehling’s solution. Although identical in chemical

composition, the various forms of starch met with in the vegetable

kingdom vary in size and exhibit characteristic differences in the

appearance of the granules. The following are measurements of several

varieties of starch granules:--

Millimetre.

Wheat ·0500

Rye ·0310

Rice ·0220

Corn ·0300

Bean ·0631

Potato ·1850

The larger granules of potato starch, when suspended in water, subside

more rapidly than those of wheat starch; they are also far more readily

ruptured.

The identification of the various starches is accomplished by means

of the microscope. Starch possesses an organised structure which,

fortunately, differs in different plants. Besides varying in size,

the granules develope in a different manner and form from centres of

growth, and therefore exhibit characteristic conditions and positions.

These distinctions, together with their effect upon polarised light,

are of great utility in the determination of the source of any

particular starch. For this purpose, it is necessary to become familiar

with the distinctive microscopical appearance of each individual

starch. A collection of those most usually met with should be made,

and, after careful study, preserved in a dried state for comparative

purposes. Polarised light is a very useful adjunct in the examination

of starch granules. In the microscopical investigation, a minute

portion of the sample is placed upon the glass slide and well moistened

with a solution of 1 part glycerine in 2 parts of water; it is then

protected by a thin glass cover, which is put on with gentle pressure.

The appearance of various starches, under polarised light, is seen in

Plate IX., where the cross lies at the hilum or nucleus of the granule

and the form and relative size is visible in outline. This plate, and

Plates VII. and XII. are copied, with permission, from Bulletin No. 11

of the Chemical Division of the U.S. Department of Agriculture. The

original negatives (made by Clifford Richardson) were used, but the

auto-types are presented in a somewhat modified form.

PLATE IX.

[Illustration: Potato × 145.]

[Illustration: Maize × 145.]

[Illustration: Wheat × 145.]

[Illustration: Rice × 450.]

[Illustration: Bean × 145.]

[Illustration: Pea × 145.]

STARCHES.

FOOTNOTES:

[50] ‘Bread Analysis.’

[51] Wanklyn applies his ammonia process (see p. 205), to the

estimation of albuminoids in vegetable substances. In this manner

he obtained the following percentages of ammonia from various

flours:--Rice, 0·62; maize and malt, 1·03; wheat and barley, 1·10; rye,

1·45; pea, 2·30.

[52] ‘An Investigation of the Composition of American Wheat and Corn.’

United States Department of Agriculture, 1883.

[53] ‘Die Menschlichen Nahrungs- und Genussmittel’ p. 420. Berlin, 1883.

BAKERS’ CHEMICALS.

The substances employed for the artificial production of porosity

in bread, as already mentioned, are sodium bicarbonate (now termed

“saleratus”), potassium bitartrate, tartaric acid, and calcium

diphosphate, the various mixtures of these compounds being known as

baking powders. Some of the above chemicals are not always used in

the pure state, and, in addition to this source of contamination,

baking powders are often excessively diluted with flour or starch, and

seriously adulterated with alum.

The sodium bicarbonate employed is generally a fairly pure article.

Common grades of the salt contain a little sodium chloride, and in some

cases as much as 2 per cent. of the corresponding sulphate; it may

also prove to be somewhat deficient in the proportion of carbonic acid

present. Cream of tartar (potassium bitartrate), is far more liable to

adulteration. A certain quantity of calcium tartrate is often found in

the commercial article, originating from its method of manufacture, and

amounting, on the average, from 6 to 7 per cent. The salt is, moreover,

sometimes intentionally mixed with alum, starch, tartaric acid, gypsum,

chalk and terra alba.

Occasionally so-called cream of tartar has been found to be wholly

composed of starch and calcium diphosphate. In the examination for

calcium tartrate and sulphate, a quantitative determination of the

total lime and sulphuric acid is made. The quantity of sulphuric

acid obtained is calculated to gypsum, any excess of lime left

being returned as tartrate. The ash in pure cream of tartar should

amount to 36·79 per cent., while that of calcium tartrate is only

21·54 per cent. Naturally, the addition of flour or starch would

materially decrease the proportion of ash. The presence of these latter

adulterants is recognised by means of the microscope, and by testing

the sample with iodine solution. It is generally required that cream of

tartar should contain at least 90 per cent. of potassium bitartrate.

_Baking powders._--The usual composition of baking powders has already

been stated. They all contain sodium bicarbonate, but differ in the

acid ingredient present, which may consist of cream of tartar, tartaric

acid, calcium diphosphate, or alum. In order to remedy the tendency to

deterioration which exists in powders entirely composed of the above

salts, it is the practice to add a considerable amount of “filling”

(corn-starch, flour, etc.). The quantity of filling employed for this

purpose varies from 20 to 60 per cent., but is as a rule, greater than

is really necessary. A small proportion of the sodium salt is often

replaced by ammonium sesquicarbonate. Alum is a more objectionable

constituent of many preparations, and it should be considered an

adulteration. The practical value of baking powder is chiefly dependent

upon the quantity of carbonic acid it liberates when decomposed, and

this is affected by the strength of the acid salt and the amount of

“filling” used. The most common varieties of baking powders are:--

(_a_) _Sodium bicarbonate and cream of tartar_, either pure or mixed

with starch. In testing this class of powders, it is usual to determine

the excessive alkalinity remaining after the decomposition with water,

by means of decinormal acid; this is put down as bicarbonate present in

excess. The proportions of sodium bicarbonate and cream of tartar are

calculated from the alkaline strength of the ash, minus the excessive

alkalinity found.

Impurities originating from the cream of tartar employed are estimated

as previously described; and the amount of starch contained is

determined by the usual methods. In some preparations, tartaric acid

is substituted for cream of tartar.

The following proportions represent the composition of a baking powder

of good quality:--

Parts.

Cream of tartar 30

Sodium bicarbonate 15

Flour 5

(_b_) _Sodium bicarbonate and calcium diphosphate._--Calcium sulphate

occurs as an impurity in the commercial phosphate and is therefore

liable to be met with in phosphate powders. In addition to phosphoric

acid, lime, etc., a determination of sulphuric acid and chlorine should

be made.

(_c_) _Sodium bicarbonate and alum._--These constitute the most

reprehensible forms of baking powder. The sanitary effects of alum have

been referred to under Flour. It may be present either as potash or

ammonia alum. The following is a fair example of an alum powder:--

Per cent.

Alum 26·45

Sodium bicarbonate 24·17

Ammonium sesquicarbonate 2·31

Cream of tartar None

Starch 47·07

From an exhaustive investigation of baking powders made by Dr. Henry

A. Mott, it was found that about 50 per cent. of these preparations

were impure, alum being the chief admixture. Of 280 samples of cream

of tartar lately examined by various American Health Boards, 100 were

adulterated; of 95 baking powders tested, 16 were adulterated.

SUGAR.

The sugars of commerce may be conveniently classified into two

varieties, viz., sucrose (cane sugar or saccharose) and dextrose (grape

sugar or glucose). The former, which is the kind almost exclusively

employed for domestic uses, is chiefly obtained from the sugar cane of

the West Indies and American Southern States (_Saccharum officinarum_),

and, in continental Europe, from the sugar beet (_Beta vulgaris_).

A comparatively small quantity is manufactured in the United States

from the sugar maple (_Acer saccharinum_), and from sorghum (_Sorghum

saccharatus_).

_Cane Sugar_ (C_{12} H_{22} O_{11}).--Among the more important chemical

properties of cane sugar are the following:--It dissolves in about

one-third its weight of cold water--much more readily in hot water--and

is insoluble in cold absolute alcohol. From a concentrated aqueous

solution it is deposited in monoclinic prisms, which possess a specific

gravity of 1·580. Cane sugar is characterised by its property of

rotating the plane of a ray of polarised light to the right; the rotary

power is 66°·6. Upon heating its solution with dilute mineral acids, it

is converted into a mixture termed “invert sugar,” which consists of

equal parts of _dextrose_ and _levulose_. The former turns the plane of

polarised light to the right, the latter to the left; but owing to the

stronger rotation exerted by the levulose, the combined rotary effect

of invert sugar is to the left, _i. e._, opposite to that possessed by

cane sugar. Invert sugar exhibits the important property of reducing

solutions of the salts of copper, which is not possessed by pure cane

sugar. Cane sugar melts at 160°; at a higher temperature (210°) it

is converted into a reddish-brown substance termed _caramel_. When

subjected to the action of ferments, cane sugar is first transformed

into invert sugar, then into alcohol and carbonic acid, according to

the reactions:--

(_a_) C_{12} H_{22} O_{11} + H_{2}O = 2 C_{6} H_{12} O_{6}.

(_b_) C_{6} H_{12} O_{6} = 2 CO_{2} + 2 C_{2} H_{6}O.

The varieties of cane sugar usually met with in commerce are the

following:--

1. Loaf sugar, consisting either of irregular fragments, or (more

often) of cut cubes.

2. Granulated sugar.

3. Soft white sugar.

4. Brown sugar, varying in colour from cream-yellow to reddish-brown.

Molasses is a solution of sugar, containing invert sugar, gummy

matters, caramel, etc., which forms the mother-liquor remaining after

the crystallisation of raw cane sugar; the name “syrup” being commonly

applied to the residual liquor obtained in the manufacture of refined

sugar.

_Dextrose_ (C_{6} H_{12} O_{6}), occurs ready-formed in grape juice,

and in many sweet fruits, very frequently associated with levulose;

it is also contained in honey, together with a small amount of cane

sugar. As already mentioned, it constitutes an ingredient of the

product obtained by the action of acids and ferments upon cane sugar.

For commercial purposes, glucose is prepared by treating grains rich

in starch, with dilute acids. In France and Germany, potatoes are used

in its manufacture; in the United States, Indian corn or maize is

almost exclusively employed. The processes used consist substantially

in first separating the starch from the grain by soaking, grinding,

and straining, then boiling it, under pressure, with water containing

about 3 per cent. of sulphuric acid, neutralising the remaining acid

with chalk, decolorising the solution by means of animal charcoal,

and concentrating it in vacuum pans. In the United States thirty-two

factories are engaged in the manufacture of glucose, which consume

about 40,000 bushels of corn daily, their annual production having an

estimated value of 10 millions of dollars. In commerce, the term grape

sugar is applied to the solid product, the syrup or liquid form being

known as glucose. The chief uses of starch sugar and glucose are in

the manufacture of table syrups, and as a substitute for malt in the

brewing of beer and ale. Their other most important applications are as

a substitute for cane sugar in confectionery, and in the preparation

of fruit jellies; as an adulterant of cane sugar, as an admixture to

genuine honey, and as a source for the preparation of vinegar.

Dextrose is soluble in 1-1/5 part of cold water, and is much more

soluble in hot water. It has a dextro-rotary power of 56°. When

separated from its aqueous solution, it forms white and opaque granular

masses, but from an alcoholic solution, it is obtained in well-defined,

microscopic needles, which fuse at 146°. Two parts of glucose have

about the same sweetening effect as one part of cane sugar.[54] It does

not become coloured when mixed with cold concentrated sulphuric acid,

which distinguishes it from sucrose; on the other hand, its solution

is coloured dark-brown if boiled with potassium hydroxide, another

distinction from cane sugar. Dextrose is capable of directly undergoing

vinous fermentation, and, like invert sugar, it possesses the property

of reducing alkaline solutions of copper salts, especially upon the

application of heat.

The chief commercial varieties of American glucose are the following:--

1. _Glucose_: Per cent. Glucose.

“Crystal H,” containing 40

“Crystal B” 45

“Crystal A” 50

2. _Grape Sugar_:

“Brewers’ grape” 70-75

“A” or “Solid grape” 75-80

“Grained” or “Granulated grape” 80-85

_Maltose_ and _levulose_ are isomers of dextrose. The former is

prepared by the action of malt or diastase upon starch. It has a

dextro-rotary power of 150° and its property of reducing copper salts

is only about 60 per cent. of that of dextrose. It is converted into

the latter compound upon boiling with dilute sulphuric acid. Levulose,

as previously stated, is formed, together with dextrose, from cane

sugar by treatment with dilute acids or with ferments. It turns the

plane of a ray of polarised light to the left, its rotary power varying

considerably at different temperatures.

_Lactose_, or milk sugar, has already been referred to under the head

of Milk. It is isomeric with cane sugar, possesses a dextro-rotary

power (58°·2), and undergoes fermentation when mixed with yeast, and

reduces alkaline copper solutions, but in a different degree from

glucose.

Many of the substances frequently enumerated as being used to

adulterate sugar are at present very seldom employed. The usual list

includes “glucose” (often meaning invert sugar), sand, flour, chalk,

terra alba, etc. Loaf sugar is almost invariably pure, although its

colour is sometimes improved by the addition of small proportions of

various blue pigments, such as ultramarine, indigo, and Prussian blue.

The presence of ultramarine was detected in about 73 per cent. of

the samples of granulated sugar tested in 1881 by the New York State

Board of Health. Tin salts[55] are also occasionally employed in the

bleaching of sugar and syrups. Granulated sugar is asserted to be

sometimes mixed with grape sugar, and powdered sugar has been found

adulterated with flour and terra alba; but the varieties which are most

exposed to admixture are the low grades of yellow and brown sugar, in

which, however, several per cent. of invert sugar are normally present.

Sand, gravel, and mites form a rather common contamination of raw

sugar. From the year 1876 to 1881, 310 samples of commercial sugar were

examined by the public health authorities of Canada, of which number

24 were reported as containing glucose, and 11 as of doubtful purity.

Of 38 samples of brown sugar recently analysed by Dr. Charles Smart,

of the National Board of Health, 9 were adulterated with glucose.

From the investigations of A. L. Colby, Analyst to the New York State

Board of Health, it was found that of the 116 samples examined, the

white sugars were practically pure; whereas, of 67 samples of brown

sugar, 4 contained glucose. Of 16 specimens of brown sugar, tested by

a commission appointed by the National Academy of Sciences in 1883,

4 contained about 30 per cent. of this body.[56] Many varieties of

sugar-house syrups, and the various forms of confectionery, are very

extensively adulterated with artificial glucose.

The average sugar-house syrup has the following composition:--

Per cent.

Water 16

Crystallisable sugar 36

Invert sugar 34

Gum, pectose, etc. 10

Ash 4

Dr. W. H. Pitt, in the Second Annual Report of the New York State

Board of Health, gives the following analysis of grocers’ mixed glucose

syrup, and of confectioners’ glucose:--

_American Grape Sugar Co.’s Syrup._

Per cent.

Ash 0·820

Water 18·857

Dextrine 34·667

Cane syrup 7·805

Glucose 37·851

-------

100·000

-------

_Confectioners’ Glucose._

Per cent.

Ash 0·431

Water 15·762

Dextrine 41·614

Glucose 42·193

-------

100·000

-------

It is stated that a large proportion of the American maple syrup and

maple sugar found on the market, consists of raw sugar, flavoured with

the essential oil of hickory-bark, for the manufacture of which letters

patent have been granted.

_Analysis of Sugar._--The examination of sugar is ordinarily confined

to the estimation of the water, ash, and determination of the nature

of the organic matters present. The proportion of water contained in

a sample is found by drying it for about two hours in an air-bath, at

a temperature of 110°. Moist and syrupy sugars, such as muscovadoes,

are advantageously mixed with a known weight of ignited sand before

drying. The ash is determined either by directly incinerating a few

grammes of the sugar in a tared platinum capsule, or by accelerating

the process of combustion by first moistening the sample with a little

sulphuric acid. In this case the bases will naturally be converted

into sulphates, and a deduction of one-tenth is usually made from

the results so obtained, in order to reduce it to terms of the

corresponding carbonates. The proportion of ash in raw cane sugar

varies somewhat, but it should not much exceed 1·5 per cent. Its

average composition, as given by Monier, is as follows:--

Calcic carbonate 49·00

Potassium carbonate 16·50

Sodium and potassium sulphates 16·00

Sodium chloride 9·00

Alumina and silica 9·50

------

100·00

------

Insoluble mineral adulterants are readily separated by dissolving a

rather considerable amount of the sample in water and filtering. In

this manner the presence of sand, terra alba, and foreign pigments may

be recognised.

The determination of the character of the organic constituents of

commercial sugars is effected, either by chemical or by physical tests,

and, in some instances, by a combination of these methods. The presence

of such adulterants, as flour or starch, is very easily detected upon a

microscopic examination of the suspected sample.

If cane sugar, containing grape sugar, is boiled with water, to which

about 2 per cent. of potassium hydroxide has been added, the solution

acquires a brown colour.

Upon mixing a solution of pure cane sugar with a solution of cupric

sulphate, adding an excess of potassium hydroxide, and boiling, only a

slight precipitation of red cupric oxide takes place. Under the same

conditions, grape sugar at once produces a copious green precipitate,

which ultimately changes to red, the supernatant fluid becoming nearly

or quite colourless. A very good method for the quantitative estimation

of grape sugar when mechanically mixed with cane sugar, is that of P.

Casamajor. It is executed by first preparing a saturated solution of

grape sugar in methylic alcohol. The sample to be tested is thoroughly

dried, and then well agitated with the methylic alcohol solution, in

which all cane sugar will dissolve; any grape sugar present remains

behind, and upon allowing the mixture to remain at rest for a short

time, forms a deposit which is again treated with the grape sugar

solution, and then collected upon a tared filter, washed with absolute

methylic alcohol, and weighed. Glucose and invert sugar are usually

quantitatively determined by means of Fehling’s solution.

As this preparation is liable to decompose upon keeping, it is

advisable to first prepare cupric sulphate solution by dissolving

exactly 34,640 grammes of the salt in 500 c.c. of distilled water,

and then make up the Rochelle salt solution by dissolving 68 grammes

of sodium hydroxide, and 173 grammes of Rochelle salt in 500 c.c. of

water, the solutions being kept separate. When required for use, 5

c.c. each of the copper and Rochelle solutions (corresponding to 10

c.c. of Fehling’s solution) are introduced into a narrow beaker, or a

porcelain evaporating dish, a little water is added, and the liquid

brought to the boiling point. The sugar solution under examination

should not contain over 0·5 per cent. of glucose. It is cautiously

added to the hot Fehling’s solution from a burette until the fluid

loses its blue colour (see p. 37). The number of c.c. required to

completely reduce 10 c.c. of Fehling’s solution, represents 0·05 gramme

of grape sugar. The foregoing volumetric method is sometimes applied

gravimetrically by adding a slight excess of Fehling’s solution to the

sugar solution, collecting the precipitated cupric oxide upon a filter

and weighing, after oxidation with a few drops of nitric acid; or, it

may be dissolved, and the copper contained deposited by electrolysis,

in which case the weight of copper obtained, multiplied by 0·538, gives

the equivalent amount of glucose. The proportion of cane sugar in a

sample of raw sugar can be determined by first directly estimating the

proportion of invert sugar contained by means of Fehling’s solution, as

just described. The cane sugar present is then inverted by dissolving

one gramme of the sample in about 100 c.c. of water, adding 1 c.c.

of strong sulphuric acid, and heating the solution in the water-bath

for 30 minutes, the water lost by evaporation being from time to

time replaced. The free acid is next neutralised by a little sodium

carbonate, its volume made up to 200 c.c., and the invert sugar now

contained estimated by Fehling’s solution. The difference in the two

determinations represents the glucose formed by the conversion of the

cane sugar; 100 parts of the glucose so produced is equivalent to 95

parts of cane sugar.

Commercial cane sugar is, however, generally estimated by the

instrument known as the saccharimeter or polariscope.

In order to convey an intelligent idea of the physical laws which

govern the practical working of the polariscope, it will first be

necessary to refer to the subject of the polarisation of light. The

transformation of ordinary into polarised light is best effected either

by reflection from a glass plate at an angle of about 56°, or by what

is known as double refraction. The former method can be illustrated by

Fig. 1, Plate X., which represents two tubes, B and C, arranged so as

to allow the one to be turned round within the other. Two flat plates

of glass, A and P, blackened at the backs, are attached obliquely to

the end of each tube at an angle of about 56°, as represented in the

figure. The tube B, with its attached plate, A, can be turned round

in the tube C without changing the inclination of the plate to a ray

passing along the axis of the tube. If a candle be now placed at I,

the light will be reflected from the plate P through the tube, and,

owing to the particular angle of this plate, will undergo a certain

transformation in its nature, or, in other words, become “polarised.”

So long as the plate A retains the position represented in the figure,

the reflected ray would fall in the same plane as that in which the

polarisation of the ray took place, and an image of the candle would

be seen by an observer stationed at O. But, suppose the tube B to be

turned a quarter round; the plane of reflection is now at right

angles to that of polarisation, and the image will become invisible.

When the tube B is turned half-way round, the candle is seen as

brightly at first; at the third quadrant it disappears, until, on

completing the revolution of the tube, it again becomes perfectly

visible. It is evident that the ray reflected from the glass plate P

has acquired properties different from those possessed by ordinary

light, which would have been reflected by the plate A in whatever

direction it might have been turned.

PLATE X.

[Illustration:

Fig. 1.

Fig. 2.

Fig. 3.

Fig. 4.

Polariscope.]

ARTOTYPE. E. BIERSTADT N. Y.

If a ray of common light be made to pass through certain crystals,

such as calc spar, it undergoes double refraction, and the light

transmitted becomes polarised. The arrangement known as Nicol’s prism,

which consists of two prisms of calc spar, cut at a certain angle and

united together by means of Canada balsam, is a very convenient means

of obtaining polarised light. If two Nicol’s prisms are placed in a

similar position, one behind the other, the light polarised by the

first (or polarising) prism passes through the second (or analysing)

prism unchanged; but if the second prism be turned until it crosses

the first at a right angle, perfect darkness ensues. While it would

exceed the limits of this work to enter fully upon the theoretical

explanations which are commonly advanced concerning the cause and

nature of this polarised, or transformed light, it may be well to state

here that common light is assumed to be composed of two systems of

beams which vibrate in planes at right angles to each other, whereas

polarised light is regarded as consisting of beams vibrating in a

single plane only. If, now, we imagine the second Nicol’s prism to be

made up of a series of fibres or lines, running only in one direction,

these fibres would act like a grating and give free passage to a

surface like a knife blade only when this is parallel to the bars,

but would obstruct it if presented transversely. This somewhat crude

illustration will, perhaps, serve to explain why the rays of light

which have been polarised by the first Nicol’s prism are allowed to

pass through the second prism when the two are placed in a similar

position, and why they are obstructed when the prisms are crossed

at right angles, it being remembered that in a polarised ray the

vibrations of the beams of light take place in a single plane.

Suppose we place between the two Nicol’s prisms, while they are at

right angles, a plate cut in a peculiar manner from a crystal of

quartz, we will discover that rays of light now pass through the

second prism, and that the field of vision has become illuminated

with beautiful colours--red, yellow, green, blue, etc., according

to the thickness of the quartz plate used. On _turning_ the second

Nicol’s prism on its axis, these colours will change and pass through

the regular prismatic series, from red to violet, or the contrary,

according to the direction of the rotation produced by the intervening

plate. Quartz, therefore, possesses the remarkable property of rotating

the plane of polarisation of the coloured rays of which light is

composed; and it has been discovered that some plates of this mineral

exert this power to the right, others to the left; that is, they

possess a right or left-handed circular polarisation. Numerous other

substances, including many organic compounds, possess this quality

of causing a rotation--either to the right or left--of a plane of

polarised light. For example, solutions of cane sugar and ordinary

glucose cause a right-handed rotation, whilst levulose and invert sugar

exert a left-handed rotation. The extent of this power is directly

proportional to the concentration of the solutions used, the length

of the column through which the ray of polarised light passes being

the same. It follows that on passing polarised light through tubes of

the same length which are filled with solutions containing different

quantities of impure cane sugar, an estimation of the amount of pure

cane sugar contained in the tubes can be made by determining the degree

of right-handed rotation produced; and it is upon this fact that the

application of the polariscope in sugar analysis is based. The optical

portions of the most improved form of the polariscope--that known as

the Ventzke-Scheibler--are represented by Fig. 2.

The light from a gas burner enters at the extremity of the instrument

and first passes through the “regulator A,” which consists of the

double refracting Nicol’s prism _a_ and the quartz plate _b_, it being

so arranged that it can be turned round its own plane, thus varying

the tint of the light used, so as to best neutralise that possessed

by the sugar solution to be examined. The incident ray now penetrates

the polarising Nicol’s prism B, and next meets a double quartz plate

C (3·75 millimetres in thickness). This quartz plate, a front view of

which is also shown in the figure, is divided in the field of vision,

one half consisting of quartz rotating to the right hand, the other

half of the variety which rotates to the left hand. It is made of the

thickness referred to owing to the fact that it then imparts a very

sensitive tint (purple) to polarised light, and one that passes very

suddenly into red or blue when the rotation of the ray is changed.

Since the plate C is composed of halves which exert opposite rotary

powers, these will assume different colours upon altering the rotation

of the ray. After leaving the double quartz plate the light, which,

owing to its passage through the Nicol’s prism B is now polarised,

enters the tube D containing the solution of cane sugar under

examination; this causes it to undergo a right-handed rotation. It next

meets the “compensator” E, consisting of a quartz plate _c_, which has

a right-handed rotary power, and the two quartz prisms _d_, both of

which are cut in a wedge shape and exert a left-handed rotation. They

are so arranged that one is movable and can be made to slide along the

other, which is fixed, thus causing an increase or decrease in their

combined thickness and rotary effect. The ray of light then passes

through the analysing Nicol’s prism F, and is finally examined by

means of the telescope G, with the objective _e_ and ocular _f_. Fig.

3 gives a perspective view of the Ventzke-Scheibler polariscope. The

Nicol’s prism and quartz plate which constitute the “regulator” are

situated at A and B, and can be rotated by means of a pinion connecting

with the button L. The polarising Nicol’s prism is placed at C, and

the double quartz plate at D. The receptacle _h_ contains the tube

P filled with sugar solution, and is provided with the hinged cover

_h´_, which serves to keep out the external light while an observation

is being taken. The right-handed quartz plate and the wedge-shaped

quartz prisms (corresponding to _c_ and _d_, Fig. 2) are situated at G,

and at E and F, and the analysing Nicol’s prism is placed at H. When

the wedge-shaped prisms have an equal thickness coinciding with that

of the quartz plate _c_ (Fig. 2) the left-handed rotary power of the

former is exactly neutralised by the right-handed rotary power of the

latter, and the field of vision seen at I is uniform in colour, the

opposing rotary powers of the two halves of the double quartz plates

C (Fig. 2) being also equalised. But if the tube, filled with a sugar

solution, is placed in the instrument, the right-handed rotary power

of this substance is added to that half of the double quartz plate

which exerts the same rotary effect (the other half being diminished

in a like degree), and the two divisions of the plate will now appear

of different colours. In order to restore an equilibrium of colour

the movable wedge-shaped quartz plate E is slid along its fellow F by

means of the ratchet M, until the right-handed rotary power of the

sugar solution is compensated for by the increased thickness of the

left-handed plate, when the sections of the plate C will again appear

uniform in colour. For the purpose of measuring the extent to which the

unfixed plate has been moved, a small ivory scale is attached to this

plate, and passes along an index scale connected with the fixed plate.

The degrees marked on the scale, which are divided into tenths, are

read by aid of a mirror _s_ attached to a magnifying glass K. When the

polariscope is in what may be termed a state of equilibrium, _i. e._

before the tube containing the sugar solution has been placed in it,

the index of the fixed scale points to the zero of the movable scale.

In the practical use of the Ventzke-Scheibler saccharimeter the

method to be followed is essentially as follows: 26·048 grammes of

the sugar to be tested are carefully weighed out and introduced into

a flask 100 cubic centimetres in capacity; water is added, and the

flask shaken until all crystals are dissolved. The solution is next

decolorised by means of basic plumbic acetate, its volume made up to

100 cubic centimetres, and a little bone-black having been added if

necessary, a glass tube, corresponding to P (Fig. 3) which is exactly

200 millimetres in length, and is provided with suitable caps, is

completely filled with the clear filtered liquid. This is then placed

in the polariscope, and protected from external light by closing the

cover shown at _h´_. On now observing the field of vision by means of

the telescope, it will be seen that the halves into which it is divided

exhibit different colours. The screw M is then turned to the right

until this is no longer the case, and absolute uniformity of colour is

restored to the divisions of the double quartz plate C (Fig. 2). The

extent to which the screw has been turned, which corresponds to the

right-handed rotation caused by the sugar solution, is now ascertained

on reading the scale by the aid of the glass K. The instrument under

consideration is so constructed that, when solutions and tubes of the

concentration and length referred to above are used, the reading on the

scale gives directly the percentage of pure crystallisable cane sugar

contained in the sample examined. For instance, if the zero index of

the fixed scale points to 96°·5 on the movable scale, after uniformity

of colour has been obtained, the sample of sugar taken contains 96·5

per cent. of pure cane sugar. The results given by the polariscope

possess an accuracy rarely, if ever, attained by any other apparatus

employed in the determination of practical commercial values.[57]

The proportion of grape sugar intentionally added to cane sugar can

also be determined by the use of the polariscope, certain modifications

being observed in its application. As previously stated, cane sugar

is converted into a mixture of dextrose and levulose, termed invert

sugar, by the action of dilute acids. While the rotary effect of

dextrose upon the plane of a ray of polarised light is constant at

temperatures under 100°, that exerted by levulose varies, it being

reduced as the temperature is increased; hence it follows that at a

certain temperature the diminished levo-rotary power of the levulose

will become neutralised by the dextro-rotary effect of the dextrose,

_i.e._ the invert sugar will be optically inactive. This temperature

has been found to approximate 90°. Since dextrose is not perceptibly

affected by the action of weak acids, it is evident that by converting

cane sugar into invert sugar and examining the product by the

polariscope at a temperature of about 90°, the presence of any added

dextrose (glucose) will be directly revealed by its dextro-rotary

action. This is accomplished by a method suggested by Messrs. Chandler

and Ricketts,[58] which consists in substituting for the ordinary

observation tube of the polariscope a platinum tube, provided with

a thermometer, and surrounded by a water-bath, which is heated to

the desired temperature by a gas burner (Plate X. Fig. 4). The sugar

solution to be examined is first treated with a little dilute sulphuric

acid, then neutralised with sodium carbonate, clarified by means of

basic plumbic acetate, filtered, and the polariscopic reading taken at

a temperature of 86° to 90°.

Since the results given by the foregoing method represent pure

dextrose, it is necessary to first ascertain the dextro-rotary

power of the particular variety of glucose probably employed for

the adulteration of the sugar under examination, and then make the

requisite correction. This process for the estimation of glucose is

especially advantageous, in that the optical effect of the invert sugar

normally present in raw cane sugars is rendered inactive.

It is sometimes desirable to determine the relative proportions of

the organic constituents which are present in commercial glucose.

These usually consist of dextrose, maltose, and dextrine, all of which

possess dextro-rotary power, but not in the same degree; that of

dextrose being 52, that of maltose 139, and that of dextrine 193. An

estimation of the amount of each can be made by first ascertaining the

total rotary effect of the sample by means of the polariscope.[59] This

is expressed by the equation

P = 52 _d_ + 139 _m_ + 193 _d´_, (1)

in which P is the total rotation observed. Upon now treating the

solution of glucose with an excess of an alkaline solution of mercuric

cyanide (prepared by dissolving 120 grammes of mercuric cyanide and 25

grammes of potassium hydroxide in 1 litre of water), the dextrose and

maltose contained in the sample are decomposed, leaving the dextrine

unaffected. A second polariscopic reading is then made, which gives the

amount of dextrine present, that is

P´ = 193 _d´_, (2)

from which the proportion of dextrine is calculated.

Subtracting the second equation from the first, we have

P - P´ = 52 _d_ + 139 _m_. (3)

Both dextrose and maltose reduce Fehling’s solution, the total

reduction (R) being the reducing per cent. of the former (_d_) added to

that of the latter (_m_). The reducing power of maltose is, however,

only 0·62 as compared with dextrine, therefore

R = _d_ + 0·62 _m_. (4)

Multiplying by 52, we have

52 R = 52 _d_ + 32·24 _m_,

and subtract from (3), which gives

P - P´ - 52 R = 106·76 _m_, (5)

whence

_m_ = (P - P´ - 52 R) / 106·76 (6)

_d_ = R - 0·62 _m_ (7)

and

_d´_ = P´/193.

FOOTNOTES:

[54] It is of interest in this connection to note the recent discovery

of a coal-tar derivative, benzoyle sulphonic imide, C_{6}H_{4} <CO/SO>

NH, commercially known as “saccharine.” This body possesses about

230 times the sweetening power of cane sugar. It bears, however, no

near chemical relation to the sugars, which, for the greater part,

constitute hexatomic alcohols. See Amer. Chem. Jour., i. p. 170, and

vol. ii. p. 181; also, Jour. Soc. Chem. Indus., No. 2, vol. vi. p. 75.

[55] Of 41 samples of molassan, tested in Massachusetts in 1885, 12

contained tin chloride.

[56] The average composition of over 100,000 samples of raw cane sugar

(mostly Cuban) tested in the United States Laboratory during the past

five years, has been as follows:--

Per cent.

Moisture 3·0

Ash 1·5

Polarisation 90°

[57] The foregoing description of the polariscope was embodied in

an article contributed by the author to Van Nostrand’s Engineering

Magazine.

[58] Journ. Amer. Chem. Soc., i. p. 1.

[59] Wiley, Chem. News, xlvi. p. 175.

HONEY.

Honey consists of the saccharine substance collected by the bee (_Apis

mellifica_) from the nectaries of flowers, and deposited by them in

the cells of the comb. “Virgin honey” is the product of hives that

have not previously swarmed, which is allowed to drain from the comb;

the inferior varieties being obtained by the application of heat and

pressure. As a result of the peculiar conditions of its formation,

honey constitutes a rather complex mixture of several bodies; indeed,

its exact composition is a matter of some doubt. The chief ingredients

are levulose and dextrose, accompanied by a small amount of cane sugar,

and inconsiderable proportions of pollen, wax, and mineral matter.

According to Dubrunfaut and Soubeiran,[60] genuine honey contains an

excess of levulose mixed with dextrose and some cane sugar. In the

course of time the latter is gradually converted into invert sugar, and

a crystalline deposit of dextrose forms, the levulose remaining fluid.

The following analyses made by J. C. Brown[61] and E. Sieben,[62] show

the general composition of pure honey:--

------------------------+----------------+----------------

| J. C. Brown. | E. Sieben.

------------------------+----------------+----------------

Dextrose | 31·77 to 42·02 | 22·23 to 44·71

Levulose | 33·56 „ 40·43 | 32·15 „ 46·89

Total glucoses | 68·40 „ 79·72 | 67·92 „ 79·57

Sucrose | .. | none „ 8·22

Wax, pollen and insol | trace to 2·10 | ..

Ash | 0·07 „ 0·26 | ..

Water at 100° | 15·50 „ 19·80 | 16·28 to 24·95

Undetermined | 4·95 „ 11·00 | 1·29 „ 8·82

------------------------+----------------+----------------

Barth has examined several varieties of genuine honey with the

following results:--

-----------------------------------+----------+-----------+-----------

| Per cent.| Per cent. | Per cent.

-----------------------------------+----------+-----------+-----------

Water | 13·60 | 15·60 | 11·06

Dry substance | 86·40 | 84·40 | 88·94

Ash | 0·28 | 0·24 | 0·90

Polarisation of 10 per }Direct | -4·6° | -5° | +11°

cent. solution (in 200 }After | | |

millimetre tube) } inversion| .. | -7·5° | +4°

{Original substance | 69·60 | 72·0 | 60·0

Sugar {After inversion | 69·50 | 77·0 | 74·6

Organic matter, not sugar | 16·52 | 7·16 | 13·44

-----------------------------------+----------+-----------+-----------

W. Bishop[63] obtained the following figures from the examination of

honey of known purity:--

-----------------------------+-----------+-------+---------+---------

|Hungarian. |Chili. |Italian. |Normandy.

-----------------------------+-----------+-------+---------+---------

Reducing sugar | 67·17 | 73·05 | 70·37 | 79·39

Crystallised sugar | 7·58 | 4·55 | 5·77 | 0·

Direct polarisation | -13·70 |-14·15 | -8·55 | -9·25

Polarisation after inversion | -15·40 |-14·85 | -12·0 | ..

-----------------------------+-----------+-------+---------+---------

The substances said to be employed in the adulteration of honey are

water, starch, cane sugar, and glucose-syrup; the last mentioned is

undoubtedly most commonly used. Hager[64] states that, by treating

corn starch with oxalic acid, a product is obtained which, on standing

two or three weeks, acquires the appearance and taste of genuine

honey; and samples of commercial honey not unfrequently wholly consist

of this or some other form of artificial glucose. The season for

the collection of honey by bees is a limited one, and any existing

deficiency in their natural source of supply is sometimes remedied by

placing vessels filled with glucose near the hives. Occasionally the

bees are also supplied with a ready-made comb, consisting, at least

partially, of paraffine. It has been asserted that in some instances,

this factitious comb is entirely composed of paraffine, but the writer

is informed that, if the sophistication is practised to a proportion

of over 10 per cent., the bees do not readily deposit the honey in the

comb.

Owing to the complex composition of honey and to the rather incomplete

character of the analyses of the genuine article at hand, the detection

of some of the forms of adulteration resorted to is a matter of

considerable difficulty. The presence of starch is best recognised by

the microscopic examination of the honey. This will likewise reveal the

absence of pollen, which may be regarded as a certain indication of

the spurious nature of the sample. There appears to exist a difference

of opinion in regard to the presence of cane sugar in genuine honey,

but it may safely be accepted that the detection of a considerable

proportion of this substance points to its artificial addition. In

all cases of suspected adulteration with cane sugar or glucose, the

determination of the sugar present by means of the polariscope and by

Fehling’s method (both before and after inversion) is indispensable. It

is commonly stated that unsophisticated honey polarises to the left,

and that a sample possessing a dextro-rotary action is necessarily

contaminated with glucose or cane sugar; but, while in the great

majority of cases this is doubtless the fact, it is equally certain

that honey of known purity has been met with which polarised to

the right. Upon the inversion of honey containing cane sugar, the

dextro-rotation is changed to a levo-rotation.

According to Lenz,[65] the specific gravity (at 17°) of a solution

of 30 grammes of pure honey in exactly twice the quantity of

distilled water is never less than 1·1110, a lower density indicating

adulteration with water. Hehner[66] states that the ash of genuine

honey is always alkaline, whereas that of artificial glucose is

invariably neutral. The proportion of phosphoric acid present in honey

varies from 0•·013 to 0•·035 per cent., which is considerably less

than the proportion contained in starch sugars. Honey contaminated with

starch sugar will generally show about 0·•10 per cent. of phosphoric

acid, and artificial honey, made from cane sugar, will usually be free

from the acid.

The addition of commercial glucose may often be detected by the

turbidity produced upon adding ammonium oxalate to a filtered aqueous

solution of the sample; this is due to the presence of calcium

sulphate, a common impurity in the commercial varieties of glucose.

If the glucose employed for admixture contains much dextrine, as is

very often the case, this fact can be utilised in its detection as

follows:--2 c.c. of a 25 per cent. solution of the honey are introduced

into a narrow glass cylinder, and 0·•5 c.c. of absolute alcohol is

cautiously added; with pure honey, the point of contact of the liquids

will remain clear or become so upon allowing the mixture to stand at

rest, whereas in presence of artificial glucose a milky turbidity will

appear between the two strata. Genuine honey may, it is true, contain

a small proportion of dextrine and exhibit a slight cloudiness when

treated with alcohol, but the difference in the degree of turbidity

caused is very considerable, and sufficient to render the test of

service.

The test may also be applied by dissolving 20 grammes of the suspected

honey in 60 c.c. of distilled water and then adding an excess of

alcohol. Under these circumstances pure honey merely becomes milky,

while, if commercial glucose is present, a white precipitate of

dextrine is formed, which can be collected and weighed. If the sugar in

the sample is determined by Fehling’s solution, both before and after

inversion with a little sulphuric acid, and an estimation of the amount

of dextrine present is made by precipitation with alcohol, it often

occurs that the quantity of the latter substance is proportional to the

difference between the amount of sugar found.

According to the late investigations of Sieben,[67] fairly

satisfactory methods for the detection and determination of glucose

syrup in honey are based upon the following facts:--

1st. When genuine honey undergoes fermentation, the substances which

remain undecomposed, are optically inactive. Glucose, or starch syrup,

on the other hand, leaves a considerable amount of dextrine, which

is strongly dextrogyrate. The test is made by dissolving 25 grammes

of honey in about 160 c.c. of water, and adding 12 grammes of yeast

(free from starch). The mixture is allowed to ferment at a moderate

temperature for two or three days, after which aluminium hydroxide is

added, and the liquid made up to 250 c.c. and then filtered. 200 c.c.

of the filtrate are evaporated to a volume of 50 c.c., and a 200 mm.

tube is then filled with the concentrated solution and examined by the

polariscope.

2nd. The substances remaining unaffected by the fermentation of pure

honey are not converted into a reducing sugar by boiling with dilute

hydrochloric acid, as is the case with those obtained from starch syrup

under the same circumstances. 25 c.c. of the solution employed for the

polarisation test, as just described, are diluted with an equal volume

of water, 5 c.c. of strong hydrochloric acid added, and the mixture

is placed in a flask and heated for an hour over the water-bath. The

contents of the flask are neutralised with potassium hydroxide, then

diluted to a volume of 100 c.c., and the proportion of reducing sugar

estimated in 25 c.c. of the solution. Honey containing different

proportions of starch sugar gave the following percentages of reducing

sugar:--

Starch-Sugar Present. | Reducing Sugar Obtained.

per cent. | per cent.

5 | 1·472

10 | 3·240

20 | 6·392

40 | 8·854

3rd. If the cane sugar originally present in genuine honey has been

changed into invert sugar, and the honey solution is boiled with a

slight excess of Fehling’s reagent, no substances capable of yielding

sugar when treated with acids will remain undecomposed. Starch syrup,

when subjected to this treatment, yields grape sugar in about the

proportion of 40 parts to every 100 parts of the syrup used. The test

is applied as follows:--14 grammes of honey are dissolved in 450 c.c.

of water, and the solution is heated over the steam-bath with 20 c.c.

of semi-normal acid, in order to invert the cane sugar present. After

heating for half an hour, the solution is neutralised, and its volume

made up to 500 c.c. 100 c.c. of Fehling’s solution are then titrated

with this solution, which may contain about 2 per cent. of invert

sugar (in case the sample examined is pure, from 23 to 26 c.c. will

be required); 100 c.c. of Fehling’s reagent are next boiled with 0·5

c.c. less of the honey solution than was found to be necessary to

completely reduce the copper. The reduced liquid is then passed through

an asbestos filter, the residue washed with hot water, the filtrate

treated with a slight excess of concentrated hydrochloric acid, and the

solution heated for one hour on the steam-bath. Sodium hydroxide is

now added, until only a very little free acid remains unneutralised,

and the solution is made up to 200 c.c. Upon well shaking the cooled

liquid, a deposit of tartar sometimes separates. 150 c.c. of the

filtered solution are finally boiled with a mixture of 120 c.c. of

Fehling’s reagent and 20 c.c. of water, and the proportion of grape

sugar estimated from the amount of metallic copper obtained. (See p.

111.) When pure honey is submitted to the preceding process, the copper

found will not exceed 2 milligrammes. The quantities of copper obtained

when honey adulterated with various proportions of starch sugar was

tested were about as follows:--

Starch Sugar | Milligrammes of

contained. | Copper found.

per cent. |

10 | 40

20 | 90

30 | 140

40 | 195

50 | 250

60 | 330

70 | 410

80 | 500

--------------------------------+-----------------------------------

|Dextrose.

| +----------------------------

| |Levulose.

| | +---------------------

| | |Invert Sugar,

Character of Samples. | | | by Fehling’s Method.

| | | +-------------

| | | |Cane Sugar.

| | | | +------

| | | | |Total

| | | | |Sugar.

--------------------------------+------+------+-------+------+------

| per | per | per | per | per

|cent. |cent. | cent. | cent.| cent.

Adulterated with cane sugar | .. | .. | 56·39 | 19·45| 76·84

„ „ „ „ and | | | | |

water |25·63 |25·42 | 51·06 | 10·62| 61·67

„ „ 15 per cent. | | | | |

glucose syrup|37·20 |31·80 | 69·18 | .. | 69·00

„ „ 65 per cent. | | | | |

glucose syrup|21·75 |19·60 | 41·30 | .. | 41·35

„ „ 40 per cent. | | | | |

glucose syrup|34·61 |23·89 | 58·83 | .. | 58·50

„ „ 40 per cent. | | | | |

glucose syrup| | | | |

and with cane| | | | |

sugar. |25·47 |23·51 | 49·04 | 7·06| 56·04

„ „ 80 per cent. | | | | |

glucose syrup|21·92 |12·83 | 35·00 | .. | 34·75

--------------------------------+------+------+-------+-------------

--------------------------------+-------------------------

|Water.

| +------------------

Character of Samples. | |Dry Substance.

| | +-----------

| | | Not Sugar.

--------------------------------+------+------+-----------

| per | per | per

|cent. |cent. |cent.

Adulterated with cane sugar |20·85 |79·15 | 2·31

„ „ „ „ and | | |

water |36·48 |63·52 | 1·85

„ „ 15 per cent. | | |

glucose syrup|18·54 |81·46 |12·46

„ „ 65 per cent. | | |

glucose syrup|18·65 |81·35 |40·00

„ „ 40 per cent. | | |

glucose syrup|17·81 |82·19 |23·69

„ „ 40 per cent. | | |

glucose syrup| | |

and with cane| | |

sugar. |19·94 |80·06 |24·02

„ „ 80 per cent. | | |

glucose syrup|18·12 |81·88 |57·13

--------------------------------+------+------+-----------

--------------------------------+--------+----------------------------

|Polarisation after Fermentation.

| +----------------------------

| I |Residue of Fermentation when

| |treated with acid gave Grape

Character of Samples. | | Sugar.

| | +------------------

| | |Milligrammes of

| | |Copper found by

| | |Method 3.

--------------------------------+--------+---------+------------------

|degrees.|per cent.| mgr.

Adulterated with cane sugar | 0·0 | 0·0 | 0

„ „ „ „ and | | |

water | 0·0 | 0·0 | 0

„ „ 15 per cent. | | |

glucose syrup| × 4·4 | 4·2 | 66

„ „ 65 per cent. | | |

glucose syrup| × 25 | 12·4 | 366

„ „ 40 per cent. | | |

glucose syrup| × 13 | 7·6 | 196

„ „ 40 per cent. | | |

glucose syrup| | |

and with cane| | |

sugar. | | |

„ „ 80 per cent. | | |

glucose syrup| × 34 | 15·2 | 492

-----------------------------------------+---------+------------------

The tabulation on p. 127 exhibits the results obtained by the

application of the foregoing tests to adulterated honey.[68]

The detection of paraffine in honeycomb is easily accomplished. Genuine

bees’-wax fuses at 64°, paraffine usually at a lower temperature.

The latter is not affected by treatment with concentrated sulphuric

acid, whereas bees’-wax is dissolved by the strong acid, and undergoes

carbonisation upon the application of heat. The amount of potassium

hydroxide required for the saponification of one gramme of bees’-wax,

as applied in Koettstorfer’s method for butter analysis (p. 71), widely

differs from the quantities consumed by Japanese wax and paraffine. Mr.

Edward W. Martin has obtained the following figures:--

Milligrammes K (O H) required

to saponify one gramme.

Bees’-wax 7·0

Japanese wax 212·95

Paraffine none

18 out of 37 samples of strained and comb honey, examined in 1885 by

the Mass. State Board of Health, were adulterated with glucose and

ordinary syrup.

FOOTNOTES:

[60] ‘Comptes Rendus,’ xxviii. p. 775.

[61] ‘Analyst,’ iii. p. 269.

[62] Zeits. Anal. Chem., xxiv. p. 135.

[63] Journ. de Pharm. et de Chem., 1884, p. 459.

[64] Pharm. Centralb. 1885, pp. 303, 327.

[65] ‘Chemiker Zeitung,’ viii., p. 613.

[66] ‘Analyst,’ x., p. 217.

[67] Zeitsch. d. Vereins. f. d. Rübenzucker Ind., p. 837.

[68] ‘Jahresberichte,’ 1884, p. 1051.

CONFECTIONERY.

Pure white candy should consist entirely of cane sugar with its water

of crystallisation, but most of the article commonly met with contains

a large proportion of glucose, and in many cases it is wholly composed

of this compound (see p. 109). Starch and terra alba (_i. e._ gypsum or

kaolin), are the other adulterants sometimes employed to fraudulently

increase the bulk and weight of candy.

The substances used for colouring purposes are more liable to be

positively deleterious. While such colouring agents as caramel,

turmeric, litmus, saffron, beet-juice, indigo, and some of the coal-tar

dyes may be considered comparatively harmless, there can be no question

in regard to the very objectionable character of certain other pigments

which are sometimes employed: these are mainly inorganic, and include

plumbic chromate, salts of copper and arsenic, zinc-white, barium

sulphate and Prussian blue. Another occasional form of adulteration

to which some kinds of confectionery are exposed, is the admixture of

artificial flavourings, such as “pear essence” (amylic and ethylic

acetates), “banana essence” (a mixture of amylic acetate and ethylic

butyrate), and oil of bitter almonds, or its imitation, nitro-benzole.

A preparation known as “rock and rye drops,” which had acquired a great

popularity among school children in several of our large cities, proved

upon analysis to consist of a mixture of glucose, flour, and fusel oil.

The examination of candy and other forms of confectionery usually

embraces the determinations of glucose, starch, flour, colouring and

flavouring agents, terra alba, and mineral admixtures generally. The

detection and estimation of glucose has already been described under

Sugar.

Starch and flour are readily detected upon treating a minute portion of

the suspected candy with a little water and submitting the mixture to a

microscopic examination, when, in their presence, the insoluble residue

will exhibit the characteristic forms of starch granules. The insoluble

portion of the sample may also be tested with a solution of iodine. The

proportion of starch can be determined by boiling the matter insoluble

in water with dilute sulphuric acid, and estimating the amount of

glucose found, by means of Fehling’s solution.

Coal-tar and vegetable compounds used for colouring purposes, can

often, be recognised by means of their behaviour with reducing and

oxidising agents, by their solubility in spirits and other menstrua,

and by the application of dyeing-tests. Thus vegetable colours may

sometimes be identified upon boiling mordanted cotton yarn in a bath

prepared from a portion of the sample containing the colouring matter,

and slightly acidulated with acetic acid. This process will likewise

generally reveal the presence of aniline dyes, unmordanted woollen

cloth being substituted for cotton, and a neutral bath being employed.

The inorganic pigments used for colouring candy are usually to be

sought for in the ash obtained upon incineration.

The presence of copper and lead is detected by the formation of

black precipitates upon saturating with sulphuretted hydrogen the

solution of the ash in hydrochloric acid; zinc, chromium, etc., are

precipitated from the filtered solution upon addition of ammonium

hydroxide and ammonium sulphide. It is frequently more convenient to

apply special tests for the particular metal thought to be present,

either directly to the pigment or to the ash. In this way, arsenic can

often be recognised by treating a portion of the colouring matter in a

test-tube, when it will sublime and collect upon the cool part of the

tube in minute crystals of arsenious acid. Or, an acidulated solution

of the detached pigments may be boiled with a piece of polished

copper-foil, upon which the arsenic will be deposited as a greyish

film: this can be sublimed, and otherwise further examined.

Copper is easily detected and estimated by placing the acid solution

of the ash in a tared platinum dish, and reducing the copper by the

electrolytic method. Chromium is recognised upon boiling the colouring

matter with potassium carbonate solution: in its presence, potassium

chromate is formed, which is submitted to the usual distinctive tests

for chromium. The colour of Prussian blue is destroyed upon warming

it with caustic alkalies: indigo, which remains unaffected by this

treatment, forms a blue solution if heated with concentrated sulphuric

acid. The presence of terra alba, barium sulphate, etc., is best

detected by the examination of the ash. Chalk, or marble-dust, is

recognised by its effervescence when treated with an acid, as well as

by the presence of a notable proportion of lime in the ash.

Many of the flavouring mixtures added to candy may be separated

by treating the sample with chloroform or petroleum naphtha and

evaporating the solution to dryness over a water-bath, when their

identity is frequently revealed by their odour and other physical

properties. Of 198 samples of the cheaper varieties of confectionery

examined by Health officials in the United States, 115 were

adulterated. Plumbic chromate is a very common addition; 41 out of 48

samples of yellow- and orange-coloured candy contained this poisonous

pigment.

BEER.

The name beer is most commonly applied to a fermented infusion of

malted barley, flavoured with hops. Its manufacture embraces two

distinct operations, _viz._, malting and brewing. Briefly considered,

the former process consists in first steeping barley (the seed of

_Hordeum distichon_) in water and allowing it to germinate by arranging

it in layers or heaps which are subsequently spread out and repeatedly

turned over, the germination being thereby retarded; it is afterwards

entirely checked by drying the grain (now known as _malt_) in cylinders

or kilns.

The degree of temperature employed in drying and roasting the barley

determines the colour and commercial character of the malt, which may

be pale, amber, brown or black. In the United States the light-coloured

varieties of malt are chiefly made. An important change which takes

place during the malting of barley is the conversion of its albuminous

constituents into a peculiar ferment, termed _diastase_, which,

although its proportion in malt does not exceed 0·003 per cent., exerts

a very energetic action in transforming starch, first into dextrine,

then into sugar (maltose). The following analyses, by Proust, exhibit

the general composition of unmalted and malted barley:--

----+---------------------+---------------+-------------+----

| | Barley. | Malt. |

| +---------------+-------------+

| Hordeine | 55 | 12 |

| Starch | 32 | 56 |

| Gluten | 3 | 1 |

| Sugar | 5 | 15 |

| Mucilage | 4 | 15 |

| Resin | 1 | 1 |

| | --- | --- |

| | 100 | 100 |

----+---------------------+---------------+-------------+----

The body termed hordeine is generally considered to be an allotropic

modification of starch.

In the brewing of beer, the malted grain is crushed by means of iron

rollers, and then introduced into the mash-tubs and digested with

water at a temperature of about 75°, whereby the conversion of the

starch into dextrine and sugar is effected. After standing for a few

hours, the clear infusion, or _wort_, is drawn off and boiled with hops

(the female flower of _Humulus lupulus_), after which it is rapidly

cooled, and then placed in capacious vats where it is mixed with

yeast and allowed to undergo the process of fermentation for several

days, during which the formation of fresh quantities of yeast and a

partial decomposition of the sugar into alcohol and carbonic acid take

place. The beer is next separated from the yeast and transferred into

clearing-vats, and, later on, into storage casks, where it undergoes

a slow after-fermentation, at the completion of which it is ready for

consumption. The quality of the water used in the process of mashing

and brewing is of great importance, and it is of special moment that it

should be free from all organic contaminations. The presence of certain

mineral ingredients, notably of calcium sulphate, is believed to exert

a beneficial effect on the character of the beer obtained.

In the United States, the best known varieties of malt liquors are

ale, porter, and lager beer. The difference between ale and porter is

mainly due to the quality of the malt used in their manufacture. Ale

is made from pale malt, porter or stout from a mixture of the darker

coloured malts, the method of fermentation employed being in both cases

that known as the “superficial” (_obergährung_), which takes place at

a higher temperature and is of shorter duration than the “sedimentary”

(_untergährung_). The latter form of fermentation, which is used in the

preparation of Bavarian or lager beer, occurs at a temperature of about

8°, and requires more time for its completion, during which the beer

is, or should be, preserved in cool cellars for several months before

it is fit for use; hence the common American name of this kind of beer,

from _lager_, a storehouse. There are three varieties of Bavarian beer,

“lager beer” proper, or the summer beer, which has been stored for

about five months; “_schenk_,” or winter beer, which is fit for use in

several weeks; and “_bock_” beer, which possesses more strength than

the former, and is made in comparatively small quantities in the spring

of the year. A mild kind of malt liquor, known as “_weiss_” beer, and

prepared by a quick process of fermentation, is less frequently met

with.

The first brewery in America is said to have been founded in New

York in the year 1644, by Jacobus, who afterwards became the first

burgomaster of the city, then New Amsterdam. Subsequently, William

Penn established a brewery in Bucks Co., Pa., and a century later,

General Putnam engaged in the manufacture of beer in the State of

Connecticut. The brewing of lager beer in the United States began to

assume prominence about thirty-five years ago. It is estimated that, at

the present time, over 2000 breweries are devoted to the preparation

of this form of malt liquor, with an invested capital of at least 60

millions of dollars, the annual production exceeding 15 millions of

barrels.[69] The industry is chiefly carried on in New York, Brooklyn,

Philadelphia, Milwaukee, St. Louis, and Cincinnati.

The composition of beer naturally varies according to the kind of

grain from which it is made and the process of fermentation employed.

The chief ingredients are alcohol, carbonic acid, sugar (maltose),

dextrine, the oil and bitter principle of hops (lupuline), albuminoids,

lactic, acetic, succinic and propionic acids, inorganic salts, and

traces of glycerine. The term “extract” is applied to the non-volatile

constituents, which include the sugar, dextrine, albuminoids, ash, etc.

The foregoing table, collated from the analyses of various chemists,

gives the general composition of some of the best known brands of malt

liquor, as well as the minimum and maximum proportions that have been

found.

--------------+-------------------------------------------------------

|Specific Gravity.

| +------------------------------------------------

| |Carbonic Acid.

| | +------------------------------------------

| | |Alcohol (by weight).

| | | +-------------------------------------

| | | |Extract.

| | | | +-------------------------------

| | | | |Albuminoids.

Variety. | | | | | +--------------------------

| | | | | |Sugar.

| | | | | | +---------------------

| | | | | | | Dextrine.

| | | | | | | +----------------

| | | | | | | |Phosphoric Acid.

| | | | | | | +----------+

| | | | | | | |Acid. |

| | | | | | | | +-----+

| | | | | | | | |Ash. |

--------------+------+-----+----+-----+----+----+----+----+-----+-----

| |p.c. |p.c.|p.c. |p.c.|p.c.|p.c.|p.c.|p.c. |p.c.

Porter |1·0207|0·16 | 5·4| 6·0 |0·83| .. |7·72|0·24|0·40 | ..

Scotch ale | .. |0·15 | 8·5|10·9 |0·77|0·34|2·50|0·19| .. | ..

Burton ale |1·0106| .. | 5·9|14·5 |0·57| .. |3·64|0·32| .. | ..

Munich | | | | | | | | | |

(Salvator)|1·0129|0·18 | 4·6| 9·4 |0·67| .. | .. | .. | .. | ..

„ (Bock) |1·0118|0·17 | 4·2| 9·2 | .. |0·80| .. | .. |0·22 |0·024

„ (Schenk) | .. | .. | 3·8| 5·8 | .. | .. |6·17|0·14| .. | ..

„ (Lager) |1·0110|0·15 | 5·1| 5·0 |0·83|0·35| .. |0·20|0·21 | ..

Berlin | .. | .. | 3·1| 5·8 | .. | .. | .. | .. |0·21 | ..

„ (Tivoli) | .. | .. |4·35| 5·14| .. | .. | .. |0·23|0·19 | ..

Erlanger | .. | .. |4·56| 4·81| .. |0·40|1·44| .. |0·48 | ..

Thüringer | | | | | | | | | |

(common) | .. | .. |2·00| .. | .. |0·31|7·71| .. | .. | ..

Culmbacher |1·0228| .. |4·00| 7·38|0·53| .. | .. |0·16| .. | ..

American | | | | | | | | | |

lager, | | | | | | | | | |

average 19 | | | | | | | | | |

samples |1·0162| .. |2·78| 6·05| .. |1·52| .. |0·19|0·305|0·105

American ale |1·0150| .. |4·69| 6·50|0·74|4·96| .. | .. |0·253|0·080

American | | | | | | | | | |

lager, 474 | | | | | | | | | |

samples | | | | | | | | | |

maximum |1·0370| .. |8·99| 9·54| .. | .. | .. | .. |0·46 |0·166

minimum |0·999 | .. |0·68| 1·28| .. | .. | .. | .. |0·10 |0·028

According to | | | | | | | | | |

König | | | | | | | | | |

maximum |1·034 |0·500| 7·3|11·24|1·98|2·45|7·85|0·40|0·48 |0·09

minimum |1·0100|0·100|1·00| 2·60|0·02|0·10|1·46|0·08|0·14 |0·02

--------------+------+-----+----+-----+----+----+----+----+-----+-----

The composition of beer ash is evidently affected by the character of

the water used in the brewing process. Blyth gives the following as the

average composition of the ash of English beers:--

Per cent.

Potash 37·22

Soda 8·04

Lime 1·93

Magnesia 5·51

Ferric oxide traces

Sulphuric acid 1·44

Phosphoric acid 32·09

Chlorine 2·91

Silica 10·82

The following results were obtained by the writer from the analysis of

the ash of American lager beer of fair quality:--

Per cent.

Silica 9·97

Alumina and ferric oxide 0·46

Lime 3·55

Magnesia 7·27

Soda 13·81

Potassa 19·59

Sulphuric acid 3·25

Chlorine 4·40

Phosphoric acid 37·70

------

100·00

Percentage of ash 0·274

Strictly speaking, normal beer consists solely of the product of malt

and hops, and the presence of any ingredients other than these should

be regarded as an adulteration. It is maintained by brewers, and

with justice, that the term “malt” is not necessarily restricted to

barley, but includes other varieties of malted grain, such as wheat,

corn, and rice. The old English law, while permitting the addition

of wholesome bitters, prohibits the use of various other substances,

but in the United States, no legal definition of pure beer has, as

yet, been formulated, and the necessity for such a measure is being

experienced.[70] The past literature of beer adulteration makes mention

of very numerous substances which, in former times, have been resorted

to as admixtures. Among these the following are the most prominent:--

1st. _Artificial bitters._--Picric acid, picrotoxine, aloes, gentian,

quassia, and wormwood. Several years ago the author had occasion to

examine two samples, imported under the name of “hop substitutes,” both

of which proved to consist of _salicine_, the bitter principle of the

willow. The fruit of the hop tree (_Ptelea trifoliata_), has also been

employed as an artificial bitter for beer.

2nd. _Flavourings._--For flavouring purposes, cayenne pepper, “grains

of paradise,” cloves, orris root, coriander seeds, the oils of anise,

nutmegs, and carraway, are stated to have been used.

3rd. _Malt substitutes._--These mainly consist of corn, rice, and

glucose.

A substitute for malt, of rather recent origin, and commercially known

as “cerealine,” is prepared by subjecting hulled and coarsely ground

Indian corn to the action of steam, the product being subsequently

pulverised by means of hot rollers. It is said to have the following

average composition:--

Water 9·98

Insoluble starch 61·43

Soluble starch, dextrine, and maltose 17·79

Albuminoids 9·07

Oil 1·22

Cellulose 0·23

Mineral matter 0·28

In addition to the foregoing, several chemical compounds, such as

ammonium carbonate, tartaric acid, alkaline phosphates, boric and

salicylic acids and glycerine are, or at least have been, employed

as accessories in the manufacture of beer. From the investigations

of the New York State Board of Health, it appears that the present

adulteration of American beer--more especially of “lager beer”--is

limited, so far as the brewer is concerned, to the use of various

substitutes for malt, the addition of salt, and of sodium bicarbonate.

The proportion of diastase obtained by the germination of barley, or

other cereals, is largely in excess of the amount required to convert

into sugar the starch actually present in the grain treated; hence

the brewer can add other forms of amylaceous substances, such as corn

or rice, to malted barley with decided economy, and the majority of

New York brewers employ such substitutes, usually in a proportion of

25 per cent. The brewer may likewise advantageously add glucose syrup

to the malt infusion, since, by its use, he arrives at the same end,

_i. e._ instead of obtaining all of his sugar as the result of the

malting process, he directly provides himself with the same body, at

least so far as it possesses value to him as a source of alcohol. The

question of the sanitary effects of the use of artificial glucose as an

adulterant of sugar and syrups, and as a substitute for malted grain

in the manufacture of beer, has given rise to extensive controversy.

In this regard, one fact seems to have been demonstrated. Glucose,

as it is now to be found on the market, is free from any appreciable

amount of deleterious contamination. The discovery of its artificial

production has given birth to a very important branch of industry, and,

according to all available reports, the commercial product at present

met with is for many purposes an economical and harmless substitute for

cane sugar, the chief objection to its application as such being the

fact that it possesses considerably less sweetening power.

The United States National Academy of Sciences, after having carefully

investigated the sanitary aspects of the glucose question, arrived at

the following conclusion:[71] “That, though having at best only about

two-thirds the sweetening power of cane sugar, yet starch sugar is in

no way inferior to the cane sugar in healthfulness, there being no

evidence before the committee that maize-starch sugar, either in its

normal condition or fermented, has any deleterious effect upon the

system, even when taken in large quantities.” In regard to the use

of glucose as a substitute for malt in beer-making, it is asserted

by some authorities that dietetic advantages to be derived from pure

malt will be to some extent wanting in the extractive matters of beer

manufactured partially from the artificial product. A distinction

between glucose and maltose, to the advantage of the latter, is also

made. The brewer, on the other hand, claims that sugar is sugar,

whether obtained from the malting of grain or from the conversion of

starch by the aid of acids. Regarding these bodies merely as sources of

alcohol, attempts to differentiate between them are of little service.

The superiority claimed for barley malt over its substitutes would

rather appear to be due to its greater richness in certain soluble

constituents, more especially those containing nitrogen and phosphoric

acid.[72] A proposed law to prohibit the use of all malt substitutes

has recently been rejected by the German Reichstag. In the English Beer

Adulteration Act (1886), however, it is directed that, in case beer

(ale or porter) made from other substances than hops and barley-malt is

offered for sale, the fact shall be mentioned on a prominent placard,

stating the nature of the foreign ingredients.

The addition of sodium bicarbonate is resorted to in order to increase

the effervescing power of the beverage, and, possibly in some

instances, to neutralise the acids formed by the souring of new and

hastily prepared beer.[73] One of the chief objections to which certain

inferior varieties of American lager beer are open is that they are

not allowed to “age” properly. The apparent gain to the brewer of such

beer consists in an economy of time and ice; he is also enabled to turn

over his invested capital sooner than the more scrupulous manufacturer,

who is thus placed in a disadvantageous position so far as trade

competition is concerned. It is stated that some of the beer made in

the neighbourhood of New York is sent out for consumption two weeks

after its brewing.[74] Beer of this character would be apt to contain

abnormally large proportions of dextrine, dextrose, etc., as well as

be contaminated with unchanged yeast and other products of imperfect

fermentation. It is said to be the practice to submit it to a process

of clarification by means of isinglass and cream of tartar, and then

impart additional life to the product by adding sodium bicarbonate,

which is used in the form of cartridges or pills, and in a proportion

of two ounces of the salt to the keg of beer.[75] Such a beverage

obviously possesses very little claim to the name “lager” beer. It is,

perhaps, to this reprehensible practice that many of the deleterious

effects on the digestive organs which sometimes follow the consumption

of considerable quantities of _poor grades_ of lager beer are to be

ascribed; and it is often asserted to be the fact that beer drinkers

who have daily drunk from 20 to 25 glasses of German beer with apparent

impunity, experience disagreeable results from the habitual consumption

of much smaller quantities of some varieties of American lager.

It should be remarked, in this connection, that the brewer is by no

means responsible for all of the sophistications to which beer is

exposed, as after it leaves his hands it may be watered by the retailer

as well as allowed to deteriorate in quality by careless methods of

preservation. From all procurable information, it would appear that the

only questionable features of beer brewing, as now generally carried on

in the United States, are the following:--

1st. The use of corn and other meals, and of artificial glucose as

substitutes for malted barley.

2nd. The use of sodium bicarbonate, to impart additional life to the

beer, and the occasional use of common salt.

Concerning the alleged employment of artificial bitters in beer

it should be stated, that a few years since, when a very marked

increase occurred in the price of hops, other bitter preparations

were advertised and offered for sale in the market; unfortunately,

but little authentic data can be secured in regard to the extent of

their use. At present, this form of adulteration has apparently been

discontinued. It is worthy of notice, that the addition of hops to

beer was originally considered a falsification, and was prohibited

in England by legal enactments. In regard to the manufacture and

sale of partially fermented beer, the question of the prevalence of

this practice must be regarded as undetermined. No objection exists

to the proper use of isinglass or other forms of gelatine for the

clarification of beer.

Of 476 samples of beer tested by Dr. F. E. Engelhardt, of the New York

State Board of Health, about one-quarter gave evidence of the use of

malt substitutes in their manufacture, but no sample was conclusively

shown to be adulterated with bitters other than hops.

The examination of beer properly includes an inspection of its

physical characteristics, such as taste, colour, and transparency, the

determination of the specific gravity, quantitative estimations of

the proportions of alcohol, carbonic acid, extractive matter, sugar,

organic acids, ash and phosphoric acid, and qualitative tests for the

detection of the presence of artificial substitutes for malt and hops.

When of good quality, beer exhibits a bright and transparent colour,

a faint but not disagreeable aroma, and a clean and slightly bitter

taste. It should be free from any signs of viscosity, the appearance of

which is usually an indication of the presence of unchanged yeast.

The specific gravity of beer is determined by first removing the excess

of carbonic acid by repeatedly agitating the sample in a capacious

glass flask, or by pouring it from one beaker into another several

times, and then filling a specific gravity bottle with the liquid and

allowing it to stand at rest until all air or gas bubbles have escaped;

the weight of the bottle and its contents is now taken at 15°. In order

to determine the proportion of alcohol present, 100 c.c. of the beer

are introduced in a suitable flask which is connected with a Liebig’s

condenser and subjected to distillation until about one-half of the

quantity taken has passed over. The distillate is then made up to its

original volume by the addition of water, and its density ascertained

by means of the specific gravity bottle, from which the percentage of

alcohol present (by weight and by volume) is readily obtained upon

referring to the alcoholometric table on p. 144. The frothing of beer

and the volatilisation of the free acids present are best obviated by

the addition of a little tannic acid and baryta-water to the sample

before the distillation. An indirect method for the determination

of alcohol in beer is also frequently employed. It is accomplished

by first ascertaining the density of the liquor, next removing the

alcohol present by evaporation over the water-bath, subsequently adding

sufficient water to restore the original volume and again taking

the specific gravity of the product. The density of spirit of equal

strength to the beer taken (X) is obtained by the formula, D/D´ = X,

in which D is the original gravity of the sample, and D´ the gravity

of the de-alcoholised liquor when made up to its first volume. The

following table (see p. 144) from ‘Watts’ Dictionary of Chemistry’

gives the percentages of alcohol by volume and weight, corresponding to

different densities at 15°.

The amount of carbonic acid is conveniently found by introducing 100

c.c. of the _well-cooled_ beer into a rather large flask, provided

with a delivery-tube which connects, first with a wash-bottle

containing concentrated sulphuric acid, next with a U-tube, filled

with fused calcium chloride. The latter is connected with a Liebig’s

bulb containing a solution of potassium hydroxide, then with a U-tube

containing solid potassium hydroxide, both of which have previously

been tared. The flask is heated over a water-bath until the evolution

of carbonic acid ceases, after which, the gas remaining in the

apparatus is caused to traverse the potash bulb by drawing air through

it. This is done by means of a tube attached to the flask and reaching

below the surface of the beer. At its other extremity, it is drawn

out to a fine point and connected with a small potash bulb (for the

retention of atmospheric carbonic acid), by aid of a rubber tube,

which permits of breaking the glass point before drawing air through

the apparatus. The amount of carbonic acid present in the sample is

ascertained by the increase of weight found in the larger potash bulb

and U-tube.

ALCOHOLOMETRIC TABLE FOR BEER, ETC.

---------+---------+-------------------

Volume | Weight |Specific Gravity.

per cent.|per cent.|

---------+---------+------------------

1·0 | 0·80 | 0·99850

1·1 | 0·88 | 0·99835

1·2 | 0·96 | 0·99820

1·3 | 1·04 | 0·99805

1·4 | 1·12 | 0·99790

1·5 | 1·20 | 0·99775

1·6 | 1·28 | 0·99760

1·7 | 1·36 | 0·99745

1·8 | 1·44 | 0·99730

1·9 | 1·52 | 0·99715

2·0 | 1·60 | 0·99700

2·1 | 1·68 | 0·99686

2·2 | 1·76 | 0·99672

2·3 | 1·84 | 0·99658

2·4 | 1·92 | 0·99644

2·5 | 2·00 | 0·99630

2·6 | 2·08 | 0·99616

2·7 | 2·16 | 0·99602

2·8 | 2·24 | 0·99588

2·9 | 2·32 | 0·99574

3·0 | 2·40 | 0·99560

3·1 | 2·48 | 0·99546

3·2 | 2·56 | 0·99532

3·3 | 2·64 | 0·99518

3·4 | 2·72 | 0·99504

3·5 | 2·80 | 0·99490

3·6 | 2·88 | 0·99476

3·7 | 2·96 | 0·99462

3·8 | 3·04 | 0·99448

3·9 | 3·12 | 0·99434

4·0 | 3·20 | 0·99420

4·1 | 3·28 | 0·99406

4·2 | 3·36 | 0·99392

4·3 | 3·44 | 0·99378

4·4 | 3·52 | 0·99364

4·5 | 3·60 | 0·99350

4·6 | 3·68 | 0·99336

4·7 | 3·76 | 0·99322

4·8 | 3·84 | 0·99308

4·9 | 3·92 | 0·99294

5·0 | 4·00 | 0·99280

5·1 | 4·08 | 0·99267

5·2 | 4·16 | 0·99254

5·3 | 4·24 | 0·99241

5·4 | 4·32 | 0·99228

5·5 | 4·40 | 0·99215

5·6 | 4·48 | 0·99202

5·7 | 4·56 | 0·99189

5·8 | 4·64 | 0·99176

5·9 | 4·72 | 0·99163

6·0 | 4·81 | 0·99150

6·1 | 4·89 | 0·99137

6·2 | 4·97 | 0·99124

6·3 | 5·05 | 0·99111

6·4 | 5·13 | 0·99098

6·5 | 5·21 | 0·99085

6·6 | 5·30 | 0·99072

6·7 | 5·38 | 0·99059

6·8 | 5·46 | 0·99046

6·9 | 5·54 | 0·99033

7·0 | 5·62 | 0·99020

7·1 | 5·70 | 0·99008

7·2 | 5·78 | 0·98996

7·3 | 5·86 | 0·98984

7·4 | 5·94 | 0·98972

7·5 | 6·02 | 0·98960

7·6 | 6·11 | 0·98949

7·7 | 6·19 | 0·98936

7·8 | 6·27 | 0·98924

7·9 | 6·35 | 0·98912

8·0 | 6·43 | 0·98900

---------+---------+------------------

The proportion of malt extract in beer can be directly determined by

the evaporation of 5 or 10 c.c. of the sample in a capacious platinum

dish over the water-bath and drying the residue until constant weight

is obtained.[76] It should be allowed to cool under a bell-jar over

calcium chloride, before weighing. Usually the estimation is made

by an indirect process, which consists in removing the alcohol by

evaporation, bringing the liquid up to its original volume by the

addition of water, and then taking its specific gravity and determining

the percentage of malt extract by means of the following table:--

SPECIFIC GRAVITY AND STRENGTH OF MALT EXTRACT.

----------+-------------

Specific | Per Cent.

Gravity. |Malt Extract.

----------+-------------

1·000 | 0·000

1·001 | 0·250

1·002 | 0·500

1·003 | 0·750

1·004 | 1·000

1·005 | 1·250

1·006 | 1·500

1·007 | 1·750

1·008 | 2·000

1·009 | 2·250

1·010 | 2·500

1·011 | 2·750

1·012 | 3·000

1·013 | 3·250

1·014 | 3·500

1·015 | 3·750

1·016 | 4·000

1·017 | 4·250

1·018 | 4·500

1·019 | 4·750

1·020 | 5·000

1·021 | 5·250

1·022 | 5·500

1·023 | 5·750

1·024 | 6·000

1·025 | 6·244

1·026 | 6·488

1·027 | 6·731

1·028 | 6·975

1·029 | 7·219

1·030 | 7·463

1·031 | 7·706

1·032 | 7·950

1·033 | 8·195

1·034 | 8·438

1·035 | 8·681

1·036 | 8·925

1·037 | 9·170

1·038 | 9·413

1·039 | 9·657

1·040 | 9·901

1·041 | 10·142

1·042 | 10·381

1·043 | 10·619

1·044 | 10·857

1·045 | 11·095

1·046 | 11·333

1·047 | 11·595

1·048 | 11·809

1·049 | 12·047

1·050 | 12·285

1·051 | 12·523

1·052 | 12·761

1·053 | 13·000

1·054 | 13·238

1·055 | 13·476

1·056 | 13·714

1·057 | 13·952

1·058 | 14·190

1·059 | 14·428

1·060 | 14·666

1·061 | 14·904

1·062 | 15·139

1·063 | 15·371

1·064 | 15·604

1·065 | 15·837

1·066 | 16·070

1·067 | 16·302

1·068 | 16·534

1·069 | 16·767

1·070 | 17·000

----------+-------------

The sugar contained in beer is best determined by by taking 50 c.c.

of the sample, adding 10 c.c. of plumbic basic acetate solution, and

making the volume of the mixture up to 300 c.c. with distilled water.

After standing for some time the solution is passed through a dry

filter. It is then examined by cautiously adding it from a burette to

10 c.c. of Fehling’s solution (diluted with 40 c.c. of distilled water

and brought to the boiling-point), until the blue colour of the latter

disappears (see p. 111). It should be borne in mind that, while 10

c.c. of Fehling’s solution are reduced by 0·05 gramme of glucose, it

requires 0·075 gramme of maltose to effect the same reduction.

In order to estimate the dextrine, 10 c.c. of the beer are reduced by

evaporation to about 4 c.c., and heated with 1 c.c. of dilute sulphuric

acid to 110° by means of an oil-bath in a strong hermetically closed

glass tube for five hours. At the completion of this operation the

solution is neutralised with sodium hydroxide, diluted, and the total

glucose determined by Fehling’s reagent, as just described. The glucose

due to the conversion of the dextrine is found by deducting the amount

of maltose (expressed in terms of glucose) previously obtained from the

total glucose; 10 parts of glucose represent 9 parts of dextrine.

The organic acids (acetic and lactic) are estimated as follows:--(_a_)

_Acetic acid_, by distilling 100 c.c. of the sample almost to

dryness, and titrating the distillate with decinormal soda solution;

(_b_) _Lactic acid_, by dissolving the residue remaining after the

distillation in water, and either determining its acidity by decinormal

soda, or by treating the residue with water and a little sulphuric

acid, adding barium carbonate to the mixture, heating in the water-bath

and filtering, the precipitate being thoroughly washed with hot water.

The filtrate is then concentrated to a syrup by evaporation, and

agitated in a test-tube with a mixture of 1 part each of sulphuric

acid, alcohol, and water, and 10 parts of ether. After standing at rest

for some time, the ethereal solution is separated by means of a pipette

and evaporated to dryness in a tared capsule. The residue (impure

lactic acid) can be weighed, or it is dissolved in water, the solution

treated with zinc carbonate, and the lactic acid determined as zinc

lactate, which contains 54·5 per cent. of the anhydrous acid.

Phosphoric acid may be estimated in the beer directly by first

expelling the carbonic acid, then adding a small quantity of potassium

acetate, heating, and titrating with a standard solution of uranium

acetate, using potassium ferrocyanide as the indicator. It can also be

determined gravimetrically in the ash.

The estimation of the ash is made by evaporating 100 c.c. of the sample

in a weighed platinum dish to dryness, and incinerating the residue at

a rather moderate heat, so as to avoid volatilisation of the chlorides.

The amount of ash in normal beer should never exceed 0·5 per cent.,

the usual proportion being about 0·3 per cent.; this would naturally

be increased by the addition of sodium bicarbonate or sodium chloride

to the beer. The complete analysis of the ash is seldom necessary, but

it is often of importance to estimate the amount of sodium chloride

contained. This is effected by dissolving the ash-residue in distilled

water and precipitating the chlorine from an aliquot portion of the

solution by silver nitrate; one part of the precipitate obtained

represents 0·409 part of common salt. The proportion of sodium

chloride in pure beer is very inconsiderable, but it may be added to

the beverage either to improve the flavour or to create thirst. For

the determination of phosphoric acid, a weighed portion of the ash

is dissolved in nitric acid, the solution evaporated to dryness, and

the residue boiled with water containing a little nitric acid. It is

then filtered, concentrated by evaporation, an excess of ammonium

molybdate solution added, and the mixture set aside for about ten

hours, after which the precipitate formed is separated by filtration

and dissolved in ammonium hydroxide. A solution of magnesium sulphate

(mixed with a considerable quantity of ammonium chloride) is now added,

and the precipitated ammonio-magnesium phosphate collected, washed,

ignited, and weighed, 100 parts of this precipitate contain 64 parts of

phosphoric anhydride (P_{2}O_{5}).

The positive detection of the presence of artificial substitutes

for malt in beer is a matter of considerable difficulty. According

to Haarstick, a large proportion of commercial glucose contains a

substance termed _amylin_, which exerts a strong dextro-rotary effect

upon polarised light, but is not destroyed by fermentation, and upon

these facts is based a process for the identification of starch-sugar

in beer. It is executed by evaporating 1 litre of the sample to the

consistency of a syrup and separating the dextrine present by the

gradual addition of 95 per cent. alcohol.[77] After standing at

rest for several hours the liquid is filtered, the greater portion

of the alcohol removed from the filtrate by distillation, and the

residual fluid evaporated to dryness over the water-bath. The solid

residue is then diluted to about a litre, yeast added, and the sugar

present decomposed by allowing fermentation to take place for three

or four days, at a temperature of 20°. It was found that, under these

conditions, pure beer afforded a solution which was optically inactive

when examined by the polariscope, while beer prepared from artificial

glucose gave a solution possessing decided dextro-rotary power. The use

of rice and glucose in the manufacture of beer is also indicated when

there is a deficiency in the proportion of phosphoric acid in the ash,

and of the extract, which applies, although to a somewhat less extent,

if wheat or corn meal has been substituted for barley malt.

The following conclusions were reached by a commission of chemists

appointed in Germany to determine standards for beer:--A fixed relation

between the quantity of alcohol and extract in beer does not invariably

exist. As a rule in Bavarian and lager beer, for 1 part by weight of

alcohol a maximum of 2 parts and a minimum of 1·5 parts of extract

should be present. In case malt has been replaced by glucose, or other

non-nitrogenous substances, the percentage of nitrogen in the extract

will fall below 0·65. The acidity should not exceed 3 c.c. of normal

alkali solution for 100 c.c. of beer. The ash should not exceed 0·3

per cent. The maximum proportion of glycerine should not exceed 0·25

per cent. For clarification, the following means are permissible:

Filtration, the use of shavings, etc., and of isinglass or other forms

of gelatine; for preservation, carbonic acid gas, and salicylic acid

may be employed--the latter, however, only in beer which is intended

for exportation to countries where its use is not prohibited.

Several samples of so-called “beer preservatives” examined by the

author, consisted of a solution of sodium salicylate and borax,

dissolved in glycerine. Salicylic acid is employed in order to

prevent fermentation in beer, which is exposed to great variations

in temperature. Its presence is detected by the following process,

suggested by Röse,[78] which is equally applicable to wine:--The beer

(or wine) is acidulated with sulphuric acid, and well shaken with its

own volume of a mixture of equal parts of ether and petroleum naphtha.

After standing at rest, the ethereal layer is removed by a pipette,

and evaporated or distilled until reduced to a few c.c. A little water

and a few drops of a dilute ferric chloride solution are then added,

and the liquid filtered: in presence of salicylic acid, the filtrate

will exhibit a violet colour. In the case of wines, where the presence

of tannic acid might interfere with the salicylic acid reaction, the

filtrate is re-acidulated, then diluted, and the treatment with the

ether mixture and iron chloride repeated. The second residue will

now show the violet coloration, even in wines rich in tannin, and

containing but 0·2 milligramme of salicylic acid per litre. The tannin

can also be removed by precipitation with gelatine, and the colour

test for salicylic acid subsequently applied. Glycerine is likewise

sometimes used as a preservative of beer, and is also added to render

the liquor richer in appearance, by communicating a viscosity to the

froth which causes it to adhere longer to the sides of the glass. It

can be quantitatively estimated by evaporating 100 c.c. of the sample

in a capsule at a temperature of 75°, until the carbonic acid has

been expelled, then adding about 5 grammes of magnesium hydroxide,

and thoroughly stirring the mixture until it forms a homogeneous,

semifluid mass. The contents of the dish are allowed to cool, and are

then well digested with 50 c.c. of absolute alcohol, and the fluid

portion afterwards separated by decantation, the residual mass being

again treated with 20 c.c. of absolute alcohol, and the alcoholic

solution thus obtained added to the first. The malose, parapeptone,

etc., present in the solution are now precipitated by adding (with

constant stirring) 300 c.c. of anhydrous ether, after which the liquid

is filtered, and the filtrate concentrated, at first by spontaneous

evaporation, subsequently by heating over the water-bath, until it

assumes the consistency of a syrup, when it is placed in an exsiccator

which connects with an air-pump, where it is allowed to remain for

twenty-four hours. The syrupy residue is then digested with 20 c.c. of

absolute alcohol and filtered, the filtrate being collected in a tared

capsule, which is again exposed to the heat of the water-bath, and

allowed to remain in the exsiccator for twelve hours, after which it

is weighed. The increase in weight gives approximately the amount of

glycerine contained in the beer examined.[79]

It is certain that many of the poisonous substances which in former

times have been detected in beer, such as strychnine, hyoscyamine,

picric acid, and picrotoxine, are not used at present. It is much

more probable that such bitters as gentian and quassia may be met

with, especially at times when hops are dear. These latter far

exceed hops in bitterness, and do not exert deleterious effects upon

health. Willow bark, or its active principle, salicine, has also been

employed. The detection of some of the most apocryphal substitutes

for hops is effected, according to Wiltstein,[80] by the following

method: One litre of the beer is concentrated over the water-bath to

a syrupy liquor, which is introduced into a rather capacious tared

cylinder and weighed. The gum, dextrine, and mineral salts are first

separated by adding to the syrup five times its weight of 95 per cent.

alcohol, with which it is thoroughly mixed, and allowed to digest for

twenty-four hours. The clear, supernatant solution is now drawn off,

and the residue treated with a fresh quantity of alcohol, which is

afterwards united with the solution first obtained, the whole being

then evaporated until the alcohol is expelled. A small portion of the

residue is dissolved in a little water, and tested for picric acid,

as described later on. The remainder is repeatedly shaken with about

six times its weight of pure benzol, which is subsequently removed

by decantation, the operation being then repeated with fresh benzol,

the two solutions added and evaporated to dryness at a very moderate

temperature. The residue thus obtained is divided into three portions,

which are placed in small porcelain dishes and tested as follows:--

To one portion a little nitric acid (sp. gr. 1·330) is added; if a

red coloration ensues, _brucine_ is present; if a violet colour,

_colchicine_. A second portion is treated with concentrated sulphuric

acid; the production of a red colour indicates the presence of

_colocynthine_. To a third portion, a few fragments of potassium

dichromate and a little sulphuric acid are added; if a purple-violet

coloration takes place, _strychnine_ is present.

The portion of the syrup which has remained undissolved by benzol is

first dried over the water-bath, and then agitated with pure amylic

alcohol, by which treatment picrotoxine and aloes, if present, will go

in solution, and impart a bitter taste to the liquid.

The solution can be examined as subsequently directed for picrotoxine;

the presence of aloes is best recognised by the characteristic

saffron-like odour possessed by this body. The syrup which remains

after the successive treatments with benzol and amylic alcohol is

next freed from any remaining traces of the latter compound by means

of blotting-paper, and then thoroughly agitated with anhydrous ether,

which is afterwards removed and allowed to spontaneously evaporate.

If the residue now obtained exhibits a wormwood-like aroma, and gives

a reddish yellow solution, which rapidly changes to a deep blue when

treated with concentrated sulphuric acid, _absinthine_ is present. The

syrup insoluble in ether may still contain quassine, gentipicrine, and

menyanthine, and the presence of any of these bodies is indicated if

it possesses a bitter taste, since the bitter principle of hops would

have been removed by the foregoing treatment with solvents. The syrup

is dissolved in a little warm water, the solution filtered and divided

into two portions. To one a concentrated ammoniacal solution of silver

nitrate is added, and the mixture heated: if it remains clear, quassine

is probably present; the formation of a metallic mirror points to the

presence of either gentipicrine or menyanthine. A second portion of the

aqueous solution is cautiously evaporated in a small porcelain capsule,

and a few drops of strong sulphuric acid are added to the residue: if

no change takes place in the cold, but upon applying heat a carmine-red

coloration appears, _gentipicrine_ is present; if a yellowish brown

colour, which afterwards changes to a violet, is produced, the presence

of _menyanthine_ is probable.[81]

Picric acid can be detected by means of the following tests:--

1. Upon shaking pure beer with animal charcoal, it becomes decolorised,

whereas beer containing picric acid retains a lemon-yellow colour after

this treatment.

2. The bitter taste of normal beer is removed by treatment with a

little plumbic diacetate and filtering, which is not the case with the

flavour imparted by the use of picric acid.

3. Unbleached wool or pure flannel will acquire a decided yellow colour

if boiled for a short time in beer adulterated with picric acid, and

afterwards washed.

4. Upon agitating 20 c.c. of the suspected beer in a test-tube with 10

c.c. of amylic alcohol, allowing the mixture to remain at rest, and

then removing the amylic alcohol, a solution is obtained which contains

any picric acid present in the sample treated. It is evaporated to

dryness, the residue dissolved in a little warm distilled water, and

the aqueous solution submitted to the following tests:--

(_a_) To one portion a concentrated solution of potassium cyanide is

added; in presence of picric acid, a blood-red colour is produced, due

to the formation of iso-purpuric acid.

(_b_) A second portion is treated with a solution of cupric-ammonium

sulphate; if picric acid be present, minute greenish crystals of

cupric-ammonium picrate will be formed.

(_c_) To a third portion, a little ammonium sulphide, containing free

ammonium hydroxide, is added; in presence of picric acid, picramic acid

is produced, the formation of which is accelerated by the application

of heat, and is made evident by the appearance of an intensely red

colour.

The detection of _cocculus indicus_, or its poisonous alkaloid,

_picrotoxine_, may be effected by first agitating the beer with

plumbic acetate, filtering, removing the lead from the filtrate by

means of sulphuretted hydrogen, and again filtering. The filtrate is

first boiled, then carefully evaporated until it possesses a thickish

consistency, when it is shaken up with animal charcoal, which is

afterwards brought upon a filter, washed with a very little cold water,

and dried at 100°. The picrotoxine possibly present is then extracted

from the animal charcoal by boiling it with strong alcohol, from

which the alkaloid separates on evaporating the solution, either in

quadrilateral prisms or in feathery tufts.

Again reverting to beer adulteration, Prof. H. B. Cornwall has lately

made an interesting report in this regard.[82] Several years ago, in

reply to a circular issued by the “Business Men’s Moderation Society

of New York City,” the “Association of United Lager Beer Brewers”

asserted that the only substitutes for barley malt employed were corn

starch, corn meal, rice, glucose, and grape sugar, no artificial

bitters being used. The addition of glucose and grape sugar, the

association stated, was not necessarily on account of economy, but

had for its object an increase in the strength of the wort, without

resorting to concentration and the production of beer of desirable

flavour and colour. Rüdlinger[83] denies that beer is subjected to

injurious adulteration in Germany. He states substantially as follows:

“Cases of sickness, frequently claimed to be caused by the beer, are

due either to excess or to the consumption of the new and incompletely

fermented beverage. It has been affirmed that brewers often economise

in hops by the use of other and deleterious bitters, and that picric

acid and strychnine have been employed for this purpose. Nonsense, once

written, is frequently copied by hundreds, and in this way circulates

among the masses. The maximum amount of hops used in beer is really

inconsiderable, and, there exists no necessity for resorting to foreign

substitutes, even in seasons when the price of hops is abnormally high,

since the proportion of this ingredient could be slightly decreased

without incurring the danger of detection which would follow the use of

artificial bitters.” On the other hand, it is certain that, _in past

years_, such injurious additions as cocculus indicus, picric acid,

aloes, etc., have actually been discovered by chemists of high standing

in bitter ale and other forms of beer. A. Schmidt,[84] asserts that

glycerine, alum, and sodium bicarbonate are added to beer, and states

that beer, poor in extractive and alcoholic constituents, is liable

to become sour, a defect which is remedied by the use of alkalies

and chalk, the resulting disagreeable taste being disguised by means

of glycerine. The same authority deprecates the use of glucose on

account of the absence of nutritious albuminoids and phosphates in this

substance. It would certainly appear obvious that the direct addition

of starch-sugar to the wort, which results in augmenting the alcoholic

strength of beer without correspondingly increasing the proportion of

valuable extractive matter, is of doubtful propriety. Grains are less

open to this objection. Of these, maize is generally regarded as the

best substitute for barley malt, both on account of its similarity in

composition and its cheapness. The International Congress of Medical

Sciences, held at Brussels in 1875, adopted the following resolutions:--

1. Genuine beer should be made from grain and hops.

2. No other substances should replace these, either wholly or partially.

3. All substitutes should be considered as adulterations, and should

come under the penalty of the law, even if not deleterious to health.

The German Brewers’ Association, at its Frankfort meeting, defined

wholesome beer as the produce of malt, hops, yeast, and water with

a partial substitution of the malt by starch meal, rice, maize, and

glucose, and regarded the use of some malt substitutes as permissible

on scientific and hygienic grounds. It recommended, however, that, in

case such substitutes are employed, the beer so prepared should be

designated by a distinctive name, such as “rice beer,” “sugar beer,”

etc.

The darker varieties of beer are sometimes artificially coloured by

the addition of caramel, and, although the result reached is virtually

the same as that caused by the over-roasting of malt, the practice is

prohibited in Germany unless the product is designated as “coloured

beer.”[85] According to Guyot, some of the Bavarian beer sold in Paris

is coloured with methyl orange.[86] Licorice is employed in beer

brewing in Germany, both on account of its sweetening power and for

clarifying purposes.

In regard to the use of artificial preservatives, such as salicylic

acid and sodium bisulphite, it is very probable that articles of

food which have been treated with these preparations are not readily

digested. Their use, moreover, should be unnecessary, if due care has

been exercised in the manufacture of the beer. This is especially

applicable to beer intended for home consumption.

FOOTNOTES:

[69] The total production of all kinds of malt liquors in the United

States was, for the fiscal year 1886, 20 millions of barrels; it is

assumed that at least three-quarters of this amount consisted of lager

beer.

[70] In Bavaria the use of all malt and hop substitutes is legally

prohibited.

[71] ‘Report of the National Academy of Sciences,’ 1883, p. 88.

[72] Hanemann has made the following determinations of fermented worts

prepared from pure malt and from malts containing 40 per cent. of each

substitute:--

---------+------------+--------------+------------+--------------+

| Pure Malt. | Maize Malt. | Rice Malt. | Starch Malt. |

---------+------------+--------------+------------+--------------+

Alcohol | 2·71 | 2·76 | 2·90 | 3·19 |

Extract | 6·59 | 6·48 | 6·25 | 5·91 |

Proteids | 0·43 | 0·39 | 0·33 | 0·28 |

---------+------------+--------------+------------+--------------+

[73] The writer is assured by a prominent New York brewer, that the

addition of sodium bicarbonate is resorted to, not so much as a remedy

for poor beer, as for the purpose of satisfying the vitiated taste of

the public, who demand a lively and sparkling beverage. The proportion

employed is claimed not to exceed one ounce to the keg of beer.

[74] ‘Annual Report Brooklyn Board of Health,’ 1885, p. 89.--The

accuracy of this statement is denied by the brewers. A blending of new

and old beer is, however, occasionally practised with, it is said, no

deleterious effects.

[75] Ibid.

[76] The albuminoids in beer may be estimated by diluting 1 c.c. of the

sample with water and then submitting it to Wanklyn’s process for water

analysis (see p. 211). The albuminoid ammonia thus obtained, multiplied

by 5·2, give the proteids in the beer taken.

[77] The dextrine can also be removed by subjecting the beer to

dialysis (see p. 183).

[78] Chem. Centralb., 1886, p. 412.

[79] Griessmayer; Corresp. Blatt. d. Ver. Anal. Chem. No. 4, Feb. 1880.

[80] Griessmayer; Corresp. Blatt. d. Ver. Anal. Chem. No. 4, Feb. 1880.

[81] A comprehensive scheme for the detection of foreign bitters in

beer, suggested by Dragendorff, will be found in the Archiv. der Pharm.

[3] iii. 295; iv. 389.

[82] Reports of Am. Health Assoc., vol. x.

[83] ‘Bierbrauerei,’ 1876.

[84] Archiv. der Pharm., xii. 392.

[85] Deutsch. Reichsanzeiger, July 31, 1885.

[86] Répert. de Pharm., xii. p. 513.

WINE.

Wine is the fermented juice of the grape of _Vitis vinifera_. In its

preparation, the fully matured grapes are usually (but not always)

first separated from the stalks, and then crushed, the _marc_ so

obtained being afterwards placed in butts provided with perforated

sides, through which the expressed juice or _must_ percolates. It

is next introduced into vats, and allowed to undergo a process of

fermentation, which is very analogous to that of beer wort. The

addition of yeast is, however, in this case unnecessary, as the

fermentation of grape-juice is spontaneous, it being due to the

generation of the fungus _Penicillium glaucum_, which is the product of

the action of atmospheric germs upon the albuminoid matters contained

in the must. The most important constituents of grape-juice are

glucose (10 to 30 per cent.), organic acids (0·3 to 1·5 per cent.),

and albuminous substances. During the fermentation the glucose is

converted into alcohol and carbonic acid, the latter being evolved in

bubbles; a deposit of potassium bitartrate and yeast-cells, forming

the _lees_, likewise occurring. This first fermentation ceases after

the lapse of several days, the period being indicated by the cessation

of escaping gas. In order to prevent the oxidation of the alcohol to

acetic acid, the liquid is removed from the lees and transferred into

casks, in which a slow after-fermentation and a further separation of

potassium bitartrate take place. The wine is subsequently stored for a

considerable time in fresh casks, during which it “ages,” and acquires

its characteristic flavour.

The more common varieties of wine are classified according to the

country of their production--into French (claret, burgundy, champagne,

etc.), German (Rhine), Spanish (sherry and port), and Italian.

The production of American wine has experienced a noteworthy increase

during the past twenty-five years. While, in 1860, less than two

millions of gallons of native wine were consumed in the United States,

in the year 1884 the quantity used exceeded seventeen millions of

gallons.[87] Aside from the general distinction of red and white,

wines are classified by their characteristic properties, as dry,

sweet, and cordial. In dry wines, such as those of the Gironde and

Rhenish districts, considerable free acid, and but little or no sugar

are contained, whereas in sweet wines (Madeira, port, etc.) a certain

proportion of the sugar remains undecomposed. Cordial wines are

distinguished by their sweetness and comparatively heavy body. The

nature of wines is materially affected by the proportion of glucose and

acids contained in the original must, as well as by the environments

of their manufacture, such as climate and temperature. From a chemical

point of view, the most important constituents of wine are the primary

products of fermentation--alcohol, succinic acid, and glycerine, but

its market value is far more dependent upon the flavour and bouquet,

which are chiefly due to the formation of secondary products, usually

included under the name “oenanthic ether,” and consisting of the ethers

of caproic, caprylic, and other organic acids.

The following table exhibits the constituents of some of the best

known varieties of wine, according to results obtained by different

authorities:--

-----------------+----------------------------------------------------

|Specific Gravity.

| +--------------------------------------------

| |Alcohol, by Weight.

| | +-------------------------------------

| | |Fixed Acids (as Tartaric).

| | | +-----------------------------

| | | |Volatile Acids (as Acetic).

Kind of Wine. | | | | +----------------------

| | | | |Total Acids.

| | | | | +---------------

| | | | | | Real

| | | | | |Tartaric Acid.

| | | | | | +--------

| | | | | | | Total

| | | | | | |Residue.

-----------------+-------+------+------+-------+------+------+--------

| | p.c. | p.c. | p.c. | p.c. | p.c. | p.c.

French (red)[88] |0·9950 |12·00 |0·420 |0·170 |0·590 |0·180 | 2·43

French (white) |0·9922 |10·84 |0·435 |0·169 |0·604 |0·102 | 1·257

Vin Ordinaire | .. | 6·99 |0·610 |0·110 |0·720 | .. | 5·04

St. Julien (1858)| .. | 9·84 |0·510 |0·140 |0·650 | .. | 2·67

Frousac | .. |10·74 |0·450 |0·270 |0·720 | .. | 2·36

Champagne | .. | 7·95 | .. | .. |0·520 | .. |12·41

Rhenish[88] |0·9934 | 9·26 |0·420 |0·110 |0·530 |0·250 | 1·850

Rüdesheimer | .. |13·32 | .. | .. |0·630 | .. | 1·840

Alsatian[88] | .. |10·38 | .. |0·6100 | .. | .. | ..

Würtemberg | .. | 7·09 |0·87 | .. | .. | .. | 2·22

Sherry[88] |0·9940 |17·20 |0·270 |0·150 |0·420 |0·018 | 4·20

Port[88] |1·0040 |18·56 |0·310 |0·080 |0·390 |0·022 | 7·55

Madeira[88] |0·9940 |17·75 |0·330 |0·160 |0·490 |0·03 | 4·35

Marsala[88] |0·9960 |16·71 |0·190 |0·110 |0·300 | .. | 4·98

Red Vœslauer | .. |10·25 |0·480 |0·060 |0·540 | .. | 1·96

Lachryma Christi | .. | 9·70 |0·460 |0·110 |0·560 | .. |23·63

White Capri | .. |10·40 |0·460 |0·190 |0·650 | .. | 1·96

Cyprus | .. |10·09 |0·480 |0·120 |0·600 | .. |23·81

Greek[88] |0·9931 |13·89 |0·233 |0·177 |0·710 |0·03 | 2·55

Hungarian[88] |0·9921 | 8·54 |0·530 |0·150 |0·700 |0·067 | 1·82

-----------------+-------+------+------+-------+------+------+--------

-----------------+--------+-----------------------------------------

| Sugar. | Ash. |Potassa (KOH).

| | | +--------------------------

| | | |Potassium Carbonate.

| | | | +------------------

| | | | | Sulphates

| | | | |and Chlorides.

| | | | | +----------

| | | | | |Phosphoric

| | | | | | Acid.

-----------------+--------+-------+------+-------+-------+----------

| p.c. | p.c. | p.c. | p.c. | p.c. | p.c.

French (red)[88] | 0·200 | 0·220 | .. | 0·060 | 0·10 | 0·03

French (white) | 0·880 | 0·197 | .. | .. | .. | 0·031

Vin Ordinaire | 0·110 | 0·450 | 0·13 | .. | .. | ..

St. Julien (1858)| 0·250 | 0·400 | .. | .. | .. | 0·080

Frousac | 0·370 | 0·270 | .. | .. | .. | 0·040

Champagne | 10·63 | 0·25 | .. | .. | .. | 0·050

Rhenish[88] | 0·012 | 0·170 | .. | 0·07 | 0·07 | 0·03

Rüdesheimer | 0·017 | 0·170 | .. | 0·07 | .. | ..

Alsatian[88] | .. | 0·178 | .. | .. | .. | 0·0253

Würtemberg | .. | 0·230 | 0·09 | .. | .. | ..

Sherry[88] | 2·56 | 0·450 | .. | 0·001 | 0·36 | 0·02

Port[88] | 4·33 | 0·280 | .. | 0·05 | 0·130 | 0·03

Madeira[88] | 2·08 | 0·39 | .. | 0·03 | 0·25 | 0·04

Marsala[88] | 3·24 | 0·22 | .. | 0·02 | 0·15 | 0·02

Red Vœslauer | 0·29 | 0·32 | 0·14 | .. | .. | ..

Lachryma Christi | 18·91 | 0·48 | 0·10 | .. | .. | ..

White Capri | 0·48 | 0·29 | 0·11 | .. | .. | ..

Cyprus | 22·12 | 0·53 | 0·11 | .. | .. | ..

Greek[88] | 0·36 | 0·37 | .. | 0·02 | 0·24 | 0·04

Hungarian[88] | 0·06 | 0·17 | .. | 0·01 | 0·08 | 0·02

-----------------+--------+-------+------+-------+-------+----------

Two varieties of Californian wine, examined by J. L. de Fremery,[89] had

the following composition:--

-------------------------------+------------------+-------------------

Grammes in 100 c.c. | Gutedel (White). | Zinfandel (Red).

-------------------------------+------------------+-------------------

Alcohol | 10·45 | 9·80

Extract | 2·0908 | 2·1270

Mineral matter | 0·1978 | 0·2218

Volatile acids (as acetic) | 0·0804 | 0·0972

Fixed acids (as tartaric) | 0·4845 | 0·4110

Potassium bitartrate | 0·1579 | 0·1428

Free tartaric acid | 0·0060 | ..

Other free acids (as tartaric) | 0·5850 | 0·5325

Sulphuric acid | 0·0384 | 0·0168

Phosphoric acid | 0·0220 | 0·0193

Chlorine | 0·0036 | 0·0054

Lime | 0·0056 | 0·0084

Magnesia | 0·0170 | 0·0160

Glycerine | 0·6133 | 0·5647

Sugar | 0·0165 | 0·0276

Polarisation | +0·2 | ..

Succinic acid | 0·0068 | 0·0097

Malic acid | 0·0324 | 0·0922

-------------------------------+------------------+-------------------

According to analyses made by R. Fresenius and R. Borgmann,[90] natural

wine has the following _average_ composition:--

Grammes in 100 c.c.

Alcohol 7·71

Extract 2·75

Free acids 0·73

Mineral matter 0·23

Glycerine 0·79

Sulphuric acid 0·038

Phosphoric acid 0·040

Lime 0·018

Magnesia 0·018

Potassa 0·092

Chlorine 0·004

Potassium bitartrate 0·200

Natural wines are frequently subjected to various processes of

treatment, designed to remedy certain defects existing in the original

must. While these do not, perhaps, all properly come under the head

of adulteration, it is certain that many of the practices resorted to

affect the dietetic quality of the wine in a deleterious manner. The

most common modes of treatment, generally considered harmless, are the

following:--

_Pasteuring_, which consists essentially in heating the wine to 60°,

with a limited supply of air, and effects the artificial ageing and

better conservation of the product. Wines which exhibit ropiness and

other diseases are restored by destroying the fungi present. This is

accomplished by subjecting the well-filled and corked bottles to a

temperature of from 45° to 100° for several hours.

A process of freezing is likewise employed for the improvement of wine.

It results in the removal of much of the cream of tartar, colouring

matter, and nitrogenous substances contained, and also causes an

increase in the alcoholic strength of the wine, thereby considerably

decreasing its tendency to undergo an after-fermentation.

The proportions of sugar and acid best adapted to the production of

wine of good quality are at least 20 per cent. of the former to not

more than 0·5 per cent. of the latter. As these conditions do not

always obtain in grape-juice, artificial methods are employed to supply

the necessary constituents. Of these, the most rational consists in

diluting the must until the amount of acid is reduced to 0·5 per

cent., and increasing the sugar to a proportion of 20 per cent. by the

addition of glucose. In a somewhat similar process, due to Petiot, the

marc is repeatedly mixed with water containing 20 per cent. of sugar,

and then subjected to fermentation. In other methods, the removal of

the excess of free acid is effected by neutralisation with pulverised

marble or neutral potassium tartrate. The use of these agents results

in the formation and subsequent separation of insoluble salts--in

the latter case, of potassium bitartrate. Another process for the

improvement and preservation of natural wine, proposed by Scheele,

consists in the addition of glycerine, in a maximum proportion of 3 per

cent., after the first fermentation has taken place.

R. Kayser[91] has made a very exhaustive investigation of wine-must

of different sources, and of the wine prepared therefrom, both in its

natural state and after having been subjected to various “processes of

improvement.” The following table shows the results obtained from the

analysis of Franken must and wine (both natural and “improved”), made

from Riessling grapes in 1880:--

-------------------+-------+------------------------------------------

| Must. |Natural Wine.

| | +-----------------------------------

| | |Gall’s Process, (Cane Sugar added).

| | | +---------------------------

| | | |Gall’s Process,

| | | |(Grape Sugar used).

| | | | +--------------------

| | | | |Chaptal’s

| | | | |Process (Calcium

| | | | |Carbonate added).

| | | | | +---------------

| | | | | |Plastered.

| | | | | | +--------

| | | | | | |Petiot’s

| | | | | | |Process

| | | | | | |(Cane

| | | | | | |Sugar

| | | | | | |added to

| | | | | | |grape

| | | | | | |husks).

| | | | | | +-+

| | | | | | |

+-------+------+-------+------+------+------+------

| p.c. | p.c. | p.c. | p.c. | p.c. | p.c. | p.c.

Alcohol | .. |6·60 |12·20 |9·10 |6·60 |6·70 |10·40

Extract |17·87 |2·53 | 2·11 |5·91 |2·19 |2·80 | 1·98

Ash | 0·33 |0·26 | 0·10 |0·17 |0·28 |0·29 | 0·16

Sulphuric acid | 0·010 |0·006 | 0·002 |0·010 |0·006 |0·077 | 0·002

Phosphoric acid | 0·031 |0·024 | 0·020 |0·021 |0·023 |0·025 | 0·017

Lime | 0·012 |0·009 | 0·007 |0·018 |0·027 |0·039 | 0·006

Magnesia | 0·012 |0·011 | 0·012 |0·009 |0·012 |0·012 | 0·008

Free acid (as | | | | | | |

tartaric) | 1·365 |1·275 | 0·765 |0·802 |0·660 |1·297 | 0·488

Total tartaric acid| 0·501 |0·342 | 0·120 |0·140 |0·014 |0·260 | 0·150

Free tartaric acid | 0·188 |0·012 | .. | .. | .. |0·160 | ..

Malic acid | 0·720 |0·715 | 0·400 |0·388 |0·710 |0·716 | 0·165

Succinic acid | .. |0·110 | 0·140 |0·114 |0·112 |0·101 | 0·127

Glycerine | .. |0·650 | 1·150 |0·800 |0·600 |0·700 | 0·900

Sugar |13·90 |0·210 | 0·180 |0·340 |0·200 |0·180 | 0·300

Potassa | 0·156 |0·117 | 0·051 |0·081 |0·134 |0·127 | 0·093

-------------------+-------+------+-------+------+------+------+------

Magnier de la Source[92] has recently made some investigations

concerning the difference in chemical composition of natural and

plastered wine; he gives the following constituents of 1 litre of

wine:--

--------------------------------------+--------+------------

|Natural.| Plastered.

+--------+------------

| gr. | gr.

Tartar | 1·94 | 0

Sulphuric acid | 2·58 | 3·10

Potassium | 1·12 | 2·46

Calcium (in soluble portion of ash) | 0 | 0·037

Calcium (in insoluble portion of ash) | 0·179 | 0·151

--------------------------------------+--------+------------

_Adulteration of Wine._--Although there may be some question in regard

to the moral status of the foregoing methods of improvement of natural

wine, numerous other practices are resorted to concerning which no

doubt can exist. The more common forms of wine adulteration include

plastering, sulphuring, fortification, blending, flavouring, colouring,

and the manufacture of fictitious imitations.

The “plastering” of wines consists in the addition of plaster of

Paris (often mixed with lime), either to the unpressed grapes or to

the must. The process, which is rather hypothetically claimed to aid

in the preservation of the wine and correct any excessive acidity,

is very objectionable, in that it determines the formation of free

sulphuric acid and acid sulphates, as well as of calcium tartrate and

potassium sulphate. The lime salt, being insoluble, is deposited with

the lees; the potassium sulphate, however, remains in solution, and

as it exerts a decided purgative effect, its presence in wine cannot

fail to be detrimental. In France, the sale of wine containing over

0·2 per cent. of potassium sulphate is prohibited. The plastering of

wine is chiefly carried on in Spain, Portugal, and southern France.

The ash of pure wine does not exceed 0·3 per cent., but in the samples

of sherry usually met with it reaches a proportion of 0·5 per cent.,

and is almost entirely composed of sulphates. The “sulphuring” of

wines is also extensively practised. It is effected either by burning

sulphur in the casks or by conducting sulphurous acid through the wine

itself, the object sought being to preserve the product and impart to

it the ripeness naturally acquired by age. Sulphured wines, while not

necessarily showing an increase in the amount of ash, can often be

recognised by the abnormally large proportion of sulphates present.

The strength and preservative qualities of wine are frequently

augmented by the addition to it of inferior sorts of brandy. Port

wine usually receives an addition of about 30 per cent., and sherry

is invariably fortified, if not to so great an extent. By the Customs

regulations in England, 10 per cent. of brandy is allowed to be added

to wines in bond, while, in France, the sophistication is equally

permitted in wines intended for export, provided the total amount of

alcohol in the fortified article does not exceed 21 per cent.

Doubtless the mixing or blending of wines constitutes the most frequent

form of their sophistication. Natural wines of the same manufacture

vary to some extent from year to year in colour, flavour, and other

characteristic properties, and mixing is resorted to in order to supply

the trade with a product always possessing nearly identical qualities.

In many cases, the flavour of wines is improved by blending, and their

intoxicating effects are also increased, both results being due to

the formation of compound ethers. Common instances of wine mixing

are the addition of Hermitage and Rousillon wines to clarets; of

Malaga and Teneriffe to port; of _solaras_ (a mixture of Amontillado

and Manzanilla) to sherry; and of a liqueur composed of sugar, some

kind of full, rich wine, and brandy, to champagne. The flavour and

bouquet of expensive wines are frequently imparted to inferior grades

by the addition of various substances, among which are elderflowers,

orris root, cherry water, essential oil of almonds, sweet briar, and

numerous perfumes, such as orange-flower water, neroli, _essence de

petit grain_, violet petals, etc. The tincture of raisin seeds is said

to communicate a genuine port flavour to poor wines, and a grain of

ambergris, triturated with a little sugar, is stated to impart a much

esteemed bouquet to a hogshead of claret. Numerous tinctures, as those

of strawberry root, raspberries, and walnuts, are likewise used. Sweet

and liqueur wines are extensively imitated at Cette and Montpelier. The

following recipes[93] will serve to illustrate the general character of

the mixtures employed:--

_For Lachryma Christi_:--

Bagnols (dry) 85 litres.

Gum kino 50 grammes.

Infusion of walnuts 1 litre.

Syrup of raisins 6 litres.

Alcohol (85°) 8 „

_For Madeira_:--

Picardan (dry) 60 litres.

Tavel (old and strong) 25 „

Infusion of walnuts 2 „

Infusion of bitter almonds 2 „

Rock candy 1½ kilos.

Brandy (58°) 10 litres.

_For Malaga_:--

Bagnols (old) 80 litres.

Syrup of raisins 10 „

Infusion of walnuts 2 „

Alcohol (85°) 8 „

_For Tokay_:--

Bagnols 80 litres.

Syrup of raisins 10 „

Dried elder flowers 300 grammes.

Infusion of white raspberries 2 kilos.

„ „ walnuts 1 kilo.

Alcohol 6 litres.

Port is frequently flavoured with a mixture of elderberry juice, grape

juice, brown sugar, and crude brandy known as “_Jerupiga_.” Sherry

often consists of Cape wine mixed with honey, bitter almonds, and

brandy. Astringency is conveyed to wines, deficient in this quality, by

means of tannin; and the property of forming a crust on the interior of

the bottle is produced, especially in port, by the admixture of cream

of tartar and gum. “Dryness” is also obtained by artificial methods. A

preparation met with in the trade, and used for this purpose, has the

following composition:[94]--

Per cent.

Glucose 28·72

Glycerine 38·40

Tannin 4·10

Dextrine 3·14

Boracic acid 4·27

Cream of tartar trace

Moisture and ash 21·37

------

100·00

------

The colour of white wines is caused by the oxidation of the tannin

present, but it is sometimes increased by the addition of the

concentrated juice of highly-coloured grapes, or by means of a small

proportion of caramel. The colour of natural red wine is due to the

presence of _oenocyanin_, a bluish-black compound, chiefly contained

in the grape skins, which is insoluble in water, but dissolves in

acidulated alcohol. In Spain and southern France, a wine prepared

from a vine known as the _Teinturier_, and possessing an intense

bluish-red colour, is extensively employed for colouring of wines.

There appears to be no doubt but that elderberries, black cherries,

mulberries, and hollyhock are also frequently used as colouring agents.

Souberian[95] mentions a mixture, termed _liqueur de fismes_, composed

of elderberries, but also containing about 5 per cent. of alum, which

is occasionally employed. The general use of several deleterious

dyes, such as logwood, cochineal, and the aniline colours, is far

more problematical. In regard to the last-mentioned agents, it has,

however, been asserted,[96] that in a commune near Beziers, of 1800

inhabitants, magenta, to the value of 30,000 francs, is annually

consumed in the adulteration of wine.

It is also worthy of remark that an aniline preparation used in Spain

for the artificial colouring of wine has recently been found to contain

1·62 per cent. of arsenic acid.[97]

Owing to the ravages of the phylloxera, a very considerable decrease in

the source of natural wines has taken place during the past few years.

Between 1883 and 1884 no less than 22 thousand acres of vineyards were

entirely destroyed in the Gironde district alone, and it is stated,

upon good authority, that the total production of wines in France in

1884 was 220 millions of gallons less than the average of the previous

ten years.[98] There is no doubt but that this decrease has greatly

stimulated the manufacture of imitation wines. These occasionally

contain a certain proportion of genuine wine as the basis, but more

frequently they consist entirely of factitious constituents. The

following recipe furnishes a fair example of those of the first class:--

Rousillon wine 50 litres.

Water 85 „

Common brandy 20 „

Vinegar 1 „

Tartaric acid 300 grammes.

Powdered orris 20 „

Wood charcoal 500 „

Agitate thoroughly, add the white of two eggs, with constant stirring;

allow to settle, and draw off.

Of late years, the production of wine from dried fruit has assumed

very extensive proportions in France. The product, which is generally

known as “_vin de raisins secs_,” is claimed by its manufacturers to be

wholesome.[99] A wine said to possess the qualities of a fair claret,

is made by submitting to fermentation the following mixture:--

White sugar 5 kilos.

Raisins 5 „

Sodium chloride 125 grammes.

Tartaric acid 200 „

Brandy 12 litres.

Water 95 „

Gall nuts 20 grammes.

Brewer’s yeast 200 „

Another recipe for Bordeaux wine is:--

Orris root 1 lb.

Water 5 galls.

Raspberry juice 1 „

Pure spirit 10 „

Essence of claret ½ lb.

Sugar syrup 1 gall.

Colour with cochineal.

It is authentically stated that in the year 1881, 52 millions of

gallons of factitious claret wine were made in France, and the

industry has certainly not diminished in extent since this date. It

is a significant fact that the importation of Spanish raisins into

France has undergone a remarkable increase during the past few

years. Nor is this species of sophistication confined to foreign

wines. Establishments are in active operation in New York City and

elsewhere in this country, where imitations of Californian hock and

claret are made from fermented infusions of dried fruit (often charged

with salicylic acid), and offered for sale at less than thirty cents

per gallon, with more than the usual trade discount.[100] According

to a reliable estimation, less than one-tenth of the wine sold as

champagne is actually the product of that district, the remainder being

fabricated from other wines or from cider.

_Analysis of Wine._--The analysis of wine comprises the following

estimations:--Specific gravity, alcohol, extract, sugar, polarisation,

glycerine, total free acids, volatile acids, free tartaric acid,

potassium bitartrate, malic acid, succinic acid, tannin, ethers, ash,

chlorine, sulphuric and phosphoric acids, and colouring matters.

_Specific gravity._--The density is determined by means of the gravity

bottle, at a temperature of 15°.

_Alcohol._--The proportion of alcohol is ascertained by the

distillation of 50 or 100 c.c. of the wine in a suitable flask, which

is connected with a Liebig’s condenser, until about half of the liquid

has passed over. The distillate is made up to the original volume with

water, and its specific gravity taken, from which the amount of alcohol

(by weight) present is calculated by aid of the usual alcohol-metric

tables (see p. 196). The result (as well as the proportions of the

other constituents) is preferably stated in grammes per 100 c.c. of

wine. The determination may also be made by first removing the alcohol

by evaporation, adding distilled water to restore the original volume,

and then estimating the density of the liquid (see under Beer, p. 142).

In unfortified wines the alcoholic strength ranges from 6 to 12 per

cent., and in wines which have received an addition of spirit, it may

vary from 12 to 22 per cent.

_Extract._--The extract is conveniently determined by evaporating 50

c.c. (measured at 15°), in a platinum dish over the water-bath, the

residue being dried for 2½ hours in the steam-oven. In case a wine rich

in sugar (containing, say, over 0·5 grammes per 100 c.c.) is under

examination, 20 c.c. will suffice for the determination. The indirect

method used in the estimation of the malt extract in beer may also be

employed. According to Girardin and Pressier, it is possible to detect

the watering of certain wines, the average composition of which is

known, by means of the proportions of extract and alcohol present. For

example, in genuine Bordeaux wines the proportion of extract ranges

from 20 to 20·8 grammes per 1000 c.c., and the amount of alcohol is

also very constant, it being a mean of 100 grammes per 1000 c.c. Should

a sample of Bordeaux wine show an extract of 14·5 grammes per litre,

the proportion of genuine wine present would be 72·5 per cent., for

(1000 × 14·5)/20 = 725·00, the remainder being water and alcohol. In

order to estimate the amount of spirits artificially added, the alcohol

contained in 72·5 parts of the wine is determined. If, for instance,

it is found to be 11 parts, then, (11 - 7·25 = ) 3·75 parts of alcohol

have been added.[101] The quantity of extract in pure natural wine

varies from 1·5 to 3 per cent., but in sweet and fortified wines, it

may reach 10 per cent. or more.

_Sugar._--The sugar in wine consists of a mixture of fruit and grape

sugar, usually in the proportion of 3 parts of the former to 1 part

of the latter. The amount of sugar is best estimated by Fehling’s

solution (see p. 111). In the case of white wines, it is advisable to

employ 100 c.c. for the determination; with sweet rich wines 25 c.c.

are sufficient. The alcohol is first removed by evaporation over the

water-bath, and the diluted liquid is next decolorised by means of

bone-black or plumbic acetate, filtered, and made alkaline by addition

of sodium carbonate. It is then made up to a volume of 200 c.c. and

gradually added to 10 c.c. of Fehling’s solution. It is always well to

test the wine by the polariscope, and, whenever the presence of cane

sugar is indicated, to invert 100 c.c. of the sample by heating with a

few drops of hydrochloric acid, and again make a sugar determination

with Fehling’s reagent after neutralisation with sodium carbonate.

_Polarisation._--The optical examination of wine is conducted by adding

20 c.c. of plumbic acetate solution to 100 c.c. of the sample, shaking

the mixture, allowing it to stand for a short time, and passing it

through a filter. If necessary the filtrate is further decolorised with

animal charcoal and again filtered. The polariscope tube is then filled

with the clear solution and the reading made. The majority of wines

exhibit a left-handed polarisation, which is due to the fact that, as

a rule, the proportion of fruit sugar present predominates over that

of grape sugar; moreover, ½ part of fruit sugar will neutralise the

dextro-rotary action of 1 part of grape sugar. In case the presence of

an excess of grape sugar is indicated by the polariscopic examination,

it is often assumed that this body has been directly added to the

wine. It sometimes occurs, however, that, in the fermentation process,

more grape sugar remains undecomposed than fruit sugar, under which

circumstances the preponderance of the former body in the resulting

wine would not prove sophistication; but, under ordinary conditions,

the presence of an excessive proportion of grape sugar may safely be

regarded as strongly pointing to the artificial addition of must syrup.

_Glycerine._--100 c.c. of the wine are reduced by evaporation on the

water-bath to 10 c.c., some pure sand added, and then milk of lime to

decided alkaline reaction, after which the mixture is evaporated nearly

to dryness. When cold, the residue is thoroughly agitated with 50 c.c.

of 96 per cent. alcohol, next heated to boiling on the water-bath,

and then passed through a filter. The insoluble residue is repeatedly

washed with more hot alcohol, the washings being added to the first

filtrate. The solution is now evaporated until it assumes a viscous

consistency. The residue is taken up with 10 c.c. of absolute alcohol,

and 15 c.c. of ether are added, the mixture being shaken and allowed

to stand at rest in a well-stoppered flask until it becomes clear. The

solution is subsequently filtered into a tared glass capsule, then

carefully evaporated to a syrupy condition over the water-bath, and

the residue dried in the steam-oven for one hour, and finally weighed.

According to Pasteur, 112·8 parts of grape sugar yield 3·6 parts of

glycerine; in natural wine, therefore, the glycerine should amount to

about 1/14th part of the alcohol present.

_Acids._--The acids in wine consist of acetic, tartaric, malic, tannic,

succinic, racemic, formic, and propionic.

_Total free Acids._--These are determined by titrating 10 c.c. of the

sample with 1/10th normal soda solution, litmus paper or tincture of

logwood being employed as the indicator. Wines containing free carbonic

acid should be repeatedly well-shaken before making the estimation. The

free acids are expressed in terms of tartaric acid (C_{4}H_{6}O_{6}).

If sulphuric acid or potassium bisulphate is present, a piece of filter

paper will be rendered brittle when immersed in the wine for some time,

and afterwards cautiously dried.

_Volatile Acids._--The volatile acids are estimated by slowly

evaporating 10 c.c. of the wine to the consistency of a syrup, and

repeating the titration with 1/10th normal alkali solution. The

difference in acidity represents the proportion of volatile acids

present, which is stated in terms of acetic acid (C_{2}H_{4}O_{2}). It

is evident that the non-volatile acids can be calculated by deducting

from the total amount of free acids, the tartaric acid corresponding

to the acetic acid found. The proportion of volatile acid in genuine

wine varies from 0·3 to 0·6 per cent. According to Dupré, in white

wine, one-fourth of the total acidity should be due to volatile acids,

and in fortified and red wine, they should not exceed a proportion of

one-third.

_Free Tartaric Acid and Potassium Bitartrate._--In the presence

of a small amount of free acids, the detection of a considerable

proportion of free tartaric acid may fairly be considered as strong

evidence that the wine is artificial. Nessler recommends the following

qualitative test:--20 c.c. of the sample are repeatedly shaken with

a little freshly prepared and finely ground cream of tartar. After

standing one hour, the solution is filtered, 3 or 4 drops of a 20

per cent. solution of potassium acetate are added, and the mixture

is allowed to remain at rest for twelve hours, when, in presence of

free tartaric acid, a precipitation will take place. The quantitative

estimation of free tartaric acid and potassium bitartrate is made

by Berthelot’s method, as follows:--Separate portions of the wine

(20 c.c. each) are introduced into two flasks, a few drops of 20 per

cent. solution of potassium acetate being added to the second flask.

200 c.c. of a mixture of equal parts of alcohol and ether are then

added to both flasks, their contents repeatedly shaken and finally

set aside for eighteen hours at a temperature between 0° and 10°. The

separated precipitates are now removed by filtration, washed with the

ether-alcohol mixture, and then titrated with 1/10th normal alkali

solution. That formed in the first flask corresponds to the potassium

bitartrate originally contained in the wine; the second represents the

total tartaric acid present. The addition of a small quantity of clean

sand will assist in the separation of the precipitates.

_Malic Acid._--A slight excess of lime-water is added to 100 c.c. of

the wine, and, after standing for some time the solution is filtered,

concentrated by evaporation to one-half its original volume, and

treated with an excess of absolute alcohol. The resulting precipitate

(consisting of calcium malate and sulphate) is collected upon a filter,

dried and then incinerated. The proportion of malic acid contained

is now estimated by volumetrically determining the amount of calcium

carbonate present by means of a normal acid solution: 1 part of calcium

carbonate represents 1·34 parts of malic acid (C_{4}H_{6}O_{5}).

_Tannic Acid._--10 c.c. of the sample are taken, the free acids

present neutralised with normal alkali solution, and a few drops of

concentrated sodium acetate solution (40 per cent.) added. A solution

of ferric chloride (10 per cent.) is then added, drop by drop,

carefully avoiding an excess. A single drop of the iron solution

represents 0·05 per cent. of tannic acid. The method of tannin

determination described under Tea (see p. 22) can also be applied.

_Succinic Acid._--500 c.c. of the wine are decolorised with bone-black,

filtered, the filtrate evaporated over the water-bath nearly to

dryness, and the residue repeatedly treated with alcohol-ether. The

solution thus obtained is concentrated, carefully neutralised with

lime-water, evaporated to dryness, and the glycerine present removed by

washing with the alcohol-ether mixture. The remaining residue is now

treated with 80 per cent. alcohol, in order to dissolve the calcium

succinate contained, every 100 parts of which represent 75·64 parts of

succinic acid (H_{6}C_{4}O_{4}). Thudichum and Dupré state that one

litre of pure wine contains from 1 to 1·5 grammes of succinic acid.

_Ethers._--The compound ethers in wine are volatile and fixed,

and exist in but minute proportions. Of the former class, ethylic

acetate C_{2}H_{3}(C_{2}H_{5})O_{2} is the most important. As already

mentioned, the aroma of wine is largely influenced by the presence of

the ethers of the fatty acids, butyric, caprylic, etc. Dupré determines

the proportion of both kinds of ethers indirectly as follows:--250 c.c.

of the wine are distilled until 200 c.c. have passed over. Water is

then added to the distillate to a volume of 250 c.c. 100 c.c. are first

titrated with 1/10th normal soda solution. Another 100 c.c. of the

distillate are next heated with a known quantity of alkali (by which

the ethers are decomposed into their corresponding acids and alcohol),

and the titration is repeated. The amount of _volatile_ ethers is then

calculated from the increased acidity shown by the second titration. In

order to determine the proportion of _fixed_ ethers, 500 c.c. of the

sample are evaporated over the water-bath to a small volume which is

made alkaline, and then subjected to distillation. The distillate is

acidulated with sulphuric acid and again distilled. The alcohol present

in the second distillate is now oxidised to acetic acid by means of

potassium dichromate, and the amount of this acid found estimated

by titration. According to Berthelot, the proportion of ethers in

genuine wine bears a fixed relation to the amounts of alcohol and acids

present: he suggests the following formula for calculating the amount

of alcohol contained in the compound ether of one litre of wine, when

etherification is complete:--

_y_ = 1·17 A + 2·8

_x_ = (_y_ × _a_) / 100,

where A is the percentage, by weight, of alcohol; _a_ the amount

of alcohol equivalent to the total free acid in one litre of wine

(assuming this to be acetic acid); _y_, the proportion per cent. of

_a_ present as compound ether in one litre of wine, when the alcoholic

strength of the wine is A; and _x_, the amount of alcohol present in

the compound ether of one litre of wine.

_The Ash._--100 c.c. of the wine are evaporated to dryness in a

platinum dish, over the water-bath, and the residue is incinerated at

a rather low temperature and weighed. By this process, the tartrates

and malates contained in the wine are converted with carbonates.

The ash of normal wine consists of potassium sulphate, carbonate,

phosphate and chloride, sodium chloride, calcium carbonate, etc.,

but, in many samples, it will be found to be largely if not entirely

composed of sulphates, which is due to the practice of sulphuring and

plastering.[102] Generally speaking, the proportion of ash in genuine

wine ranges from 0·15 to 0·30 per cent.

_Chlorine._--100 c.c. of the sample are neutralised with sodium

carbonate, evaporated to dryness, and the residue gently ignited.

It is then extracted with boiling water, filtered, and the chlorine

determined by means of silver nitrate, either volumetrically or

gravimetrically.

_Sulphuric Acid._--100 c.c. are acidulated with hydrochloric acid, the

liquid heated to boiling, and the sulphuric acid precipitated by barium

chloride. The precipitate is well washed, dried, and weighed. 100 parts

represent 42·49 parts H_{2}SO_{4}. Pure wine contains from 0·109 to

0·328 gramme of monohydrated sulphuric acid per litre (corresponding to

0·194 to 0·583 gramme potassium sulphate). The presence of an excess of

this maximum amount indicates that the wine has been plastered.

_Phosphoric Acid._--100 c.c. of the wine are evaporated, the residue

ignited, dissolved in a little water, acidulated with nitric acid,

and then added to an excess of solution of ammonium molybdate. After

standing over night the separated precipitate is dissolved in ammonia

and the phosphoric acid determined by means of an ammoniacal solution

of magnesium sulphate. 100 parts of the precipitate thus obtained

correspond to 63·96 parts of phosphoric acid. The former belief

that the best qualities of wine contain the largest proportion of

phosphoric acid does not appear to be invariably correct.

_Salicylic Acid._[103]--The determination of this acid is accomplished

as follows:--100 c.c. of the sample are repeatedly agitated with

chloroform, which is subsequently separated and evaporated to dryness.

The residue is re-crystallised from chloroform and weighed; its

identity can be established by dissolving it in water and adding

solution of ferric chloride (see p. 149).

_Sulphurous Acid._--For the detection and estimation of sulphurous

acid, the following methods have been recommended:--500 c.c. of

the wine are placed in a flask, the exit-tube of which dips into a

test-tube which is suitably cooled, and subjected to distillation. When

about 2 c.c. have distilled, a few drops of a _neutral_ solution of

silver nitrate are added to the distillate: in presence of sulphurous

acid, a white curdy precipitate will be formed, which differs from

silver chloride in being soluble in nitric acid. According to

Haas,[104] this test is not invariably decisive, as pure wine may cause

the precipitation under certain conditions; moreover, acetic acid is

said to render silver nitrate turbid in strong alcoholic solutions.

Sulphurous acid can be quantitatively determined by adding phosphoric

acid to 100 c.c. of the wine, and distilling it in an atmosphere of

carbonic acid gas. The distillate is received in 5 c.c. of normal

iodine solution. When one-third of the sample has passed over, the

distillate (which should still contain an excess of free iodine),

is acidulated with hydrochloric acid, and the sulphuric acid formed

precipitated with barium chloride.

_Colouring matters._--Very numerous processes have been published for

the detection of foreign and artificial colouring matters in wine.

Among those suggested are the following:--

1. A few drops of the sample are placed in succession on the smooth

surface of a piece of white calcined lime, and notice taken of the

tint produced. The following colours are stated to occur with pure and

artificially coloured wine:--

Natural red wine yellowish brown.

Wine coloured with fuchsine rose colour.

„ „ „ Brazil wood „ „

„ „ „ logwood reddish violet.

„ „ „ black hollyhock yellowish brown.

„ „ „ poke-berries yellowish red.

2. If ammonium hydroxide be added to the suspected sample to distinct

alkaline reaction, then a little ammonium sulphide and the liquid

filtered, the filtrate from genuine wine will possess a green tint,

whereas that obtained from artificially coloured wine will exhibit

other colours, such as red, blue, violet, or brown.

3. 100 c.c. of the wine are evaporated to about one-half of the

original volume, ammonium hydroxide added to alkaline reaction, and the

liquid thoroughly shaken. Ether is then added, and the mixture again

well shaken. It is next introduced into a separator, and allowed to

stand at rest until the ether has risen to the surface, when the lower

stratum is drawn off, and the residual ether washed by agitation with

water, which is subsequently removed. The ethereal solution is now

transferred to a flask connected with a Liebig’s condenser, a piece of

white woollen yarn introduced into the liquid, and the contents of the

flask distilled at a gentle heat: in presence of the smallest amount of

fuchsine, the wool will acquire a very perceptible reddish hue.

4. A slight excess of ammonium hydroxide is added to 50 c.c. of the

wine, a piece of white woollen fabric introduced, and the liquid

boiled until the alcohol and ammonia are expelled. By this treatment

it will be found that most aniline colouring matters, if present,

become attached to the wool. Their presence can be corroborated by

removing the fabric, washing and pressing it, and then dissolving it,

with constant stirring, in a hot solution of potassium hydroxide. When

solution has taken place, the liquid is allowed to cool, and one-half

its volume of alcohol is added, then an equal volume of ether. The

mixture is vigorously shaken, and, after remaining at rest for some

time, the supernatant ethereal solution is removed, introduced into

a test-tube, and a drop or two of acetic acid added. In presence of

fuchsine, its characteristic colour will now become apparent. Methyl

violet and aniline blue are separated by an analogous process.

5. Logwood and cochineal may be detected by agitating 100 c.c. of the

suspected wine with manganic peroxide, and filtering. The filtrate

afforded by pure wine will be colourless.

6. In Dupré’s process,[105] cubes of jelly are first prepared by

dissolving 1 part of gelatine in 20 parts of hot water, and pouring

the solution into moulds to set. These are immersed in the wine under

examination for 24 hours, then removed, slightly washed, and the depth

to which the colouring matter has permeated is observed: pure wine will

colour the gelatine very superficially; the majority of other colouring

principles (e.g. fuchsine, cochineal, logwood, Brazil wood, litmus,

beetroot, and indigo) penetrate the jelly more readily and to a far

greater degree. Dilute ammonium hydroxide dissolves from the stained

cake the colouring matter of logwood and cochineal, but not that

derived from fuchsine or beetroot.

7. The colouring principle of genuine wine when subjected to dialysis,

does not pass through the animal membrane to any decided extent, while

that of logwood, cochineal, and Brazil wood easily dialyses.

8. Many of the foreign dyes added to wine are precipitated by a

solution of basic plumbic acetate. The precipitate obtained upon

treating 10 c.c. of the sample with 3 c.c. of this reagent is collected

on a filter and washed with a 2 per cent. solution of potassium

carbonate, which dissolves cochineal, sulphindigotic acid and aniline

red. The latter is separated upon neutralising the solution with acetic

acid, and shaking with amylic alcohol, which, in its presence, will

acquire a rose colour. The liquid is next acidulated with sulphuric

acid, and again agitated with amylic alcohol, by which the carminamic

acid, originating from cochineal, is isolated. Any remaining indigo

(as well as the carminamic acid) is to be subsequently identified by

means of its spectroscopic reactions. Upon treating the portion of the

plumbic acetate precipitate which remains undissolved by potassium

carbonate with a dilute solution of ammonium sulphide, the colouring

matter of pure wine and of logwood is dissolved. If, in presence of

logwood, the original sample is shaken with calcium carbonate mixed

with a little calcium hydroxide solution and filtered, the filtrate

will exhibit a decided red tint, but, if the wine treated be pure,

little or no coloration will be produced.

9. An artificial colouring for wine, known as _rouge végétale_, is not

uncommonly employed. According to Amthor,[106] its presence can be

recognised as follows:--100 c.c. of the wine are distilled until all

alcohol is removed. The residual liquid is strongly acidulated with

sulphuric acid, and agitated with ether. Some woollen yarn is next

introduced into the ethereal solution, which is then evaporated over

the water-bath. In presence of _rouge végétale_, the wool will acquire

a brick-red colour, which turns violet upon treatment with ammonium

hydroxide.

10. Cauzeneuve and Lepine[107] state that acid aniline red,

“naphthol-yellow S,” and roccelline red are harmless, whereas safranine

and ordinary Martius’ yellow are decidedly poisonous.

The presence of “Bordeaux red”[108] is recognised by first adding

sodium sulphate to the suspected wine, then a solution of barium

chloride: the artificial dye is carried down with the precipitated

barium sulphate, from which it can be extracted by means of sodium

carbonate solution. The brownish-red liquid thus obtained acquires

a deep red colour if acidulated with acetic acid, which it readily

communicates to silk upon boiling. Natural red wine fails to produce a

coloration under the same circumstances.

For the detection of the presence of artificial colouring matter

the following process is used in the Municipal Laboratory in

Paris:--Preliminary tests are made--

1st. By soaking pieces of chalk in an aqueous solution of egg-albumen;

these are dried and applied for use by dropping a little of the wine

upon them, and noting the coloration produced. Natural coloured wine

usually causes a greyish stain, which, in highly coloured varieties,

may verge to blue.

2nd. Baryta water is added to the wine under examination until the

mixture acquires a greenish hue, after which it is shaken with acetic

ether or amylic alcohol. If the wine be pure, the upper layer remains

colourless, even after acidulation with acetic acid; whereas, in

presence of _basic_ coal-tar dyes, such as fuchsine, amidobenzole,

safranine, chrysoidine, chrysaniline, etc., characteristic colorations

will be obtained.

3rd. A few c.c. of the sample are made alkaline by the addition of

dilute potassium hydroxide, some mercuric acetate added, and the

mixture agitated and filtered. With pure wines, the filtrate is

colourless; in the presence of _acid_ coal-tar derivatives, it is red

or yellow.

The general character of the artificial dye contained in the wine

having been ascertained by the foregoing tests its more precise nature

is determined as follows:--

In case the foreign colouring is _basic_, the supernatant layer

obtained in the second test is separated, and divided into two

portions; one portion being evaporated with pure woollen yarn, the

other with filaments of silk. The dyed threads are then subjected to

the following tests:--

(_a_) _Rose-aniline or safranine_ affords a red coloration; safranine

usually attaches itself only on silk.

(_b_) _Soluble aniline violet_ produces coloured threads which become

green upon treatment with hydrochloric acid, the primitive colour

reappearing upon dilution with water.

(_c_) _Mauve-aniline_ gives a colour which turns blue upon addition of

the acid.

(_d_) _Chysotoluidine_ causes a coloration which is only slightly

affected by the acid, but which is discharged upon boiling with zinc

powder; upon protracted exposure to the air the colour reappears.

(_e_) _Chrysoidine_ and _Amidonitrobenzole_ produce yellow colours, the

former turning poppy-red if treated with sulphuric acid, the latter,

scarlet. A general characteristic of dyes, similar to rose-aniline, is

that they are decolorised by treatment with sodium bisulphite.

If the presence of an _acid_ coal-tar dye is indicated by the third

preliminary test, the following special methods of procedure are

employed:--

Two portions of the wine are saturated respectively with hydrochloric

acid and with ammonium hydroxide water, and each portion is strongly

agitated with acetic ether. The ethereal layers are removed by means

of a pipette, then mixed together, evaporated to dryness, the residue

obtained treated with a drop of concentrated sulphuric acid, and

observations made of the colour obtained:--

(_a_) Roccelline affords a violet colour.

(_b_) Bordeaux, R. and B. „ blue „

(_c_) Panceau R., R.R., R.R.R. „ scarlet „

(_d_) Panceau, B. „ red „

(_e_) Biebrich red „ green to violet colour.

(_f_) Tropeoline, O.O.O. „ red colour.

(_g_) Tropeoline, O., and Chrysoidine „ orange-yellow colour.

(_h_) Tropeoline, O.O. „ violet-red „

(_i_) Eosine „ yellow „

The method employed in the Paris Municipal Laboratory for the detection

of dried fruit wine, or of added commercial glucose, is substantially

the following:--A little beer-yeast is added to 300 c.c. of the

suspected wine, and the mixture is allowed to undergo fermentation

at a temperature of about 30°. When the fermentation is completed,

the filtered liquid is introduced into a dialyser, the outer water of

which is automatically renewed. The process of dialysis is continued

until the outer water ceases to show a rotary effect when examined by

the polariscope, after which it is neutralised with calcium carbonate

and evaporated to dryness over the water-bath, with constant stirring.

The residue obtained is treated with 50 c.c. of absolute alcohol and

filtered, the insoluble matters being twice washed with 25 c.c. of

alcohol. The alcoholic filtrates are next decolorised by means of

animal charcoal, and evaporated to dryness, and the solid residue is

dissolved in 30 c.c. of water and polarised. Genuine claret, when

tested in this manner, fails to exhibit a rotary power, or is but

slightly dextrogyrate, whereas fruit wines, and those containing

artificial starch sugar, strongly rotate respectively to the left or to

the right.

The following are some of the conclusions arrived at by a commission,

appointed by the German Government, to inquire into uniform methods

for wine analysis, and establish standards of purity for genuine

wine.[109]

(_a_) After deducting the non-volatile acids, the extract in natural

wine should amount to at least 1·1 gramme per 100 c.c.; after deducting

the free acids, to at least 1 gramme per 100 c.c.

(_b_) Most natural wines contain one part of ash to every 10 parts of

extract.

(_c_) The free tartaric acid should not exceed 1/6th of the total

non-volatile acids.

(_d_) The relation between the alcohol and glycerine varies in natural

wines between 100 parts alcohol to 7 parts glycerine, and 100 parts

alcohol to 14 parts glycerine. These proportions do not apply, however,

to sweet wines.

(_e_) Genuine wines seldom contain less than 0·14 gramme of ash, nor

more than 0·05 gramme of sodium chloride per 100 c.c.

According to the analyses of Moritz, the maximum and minimum relative

proportions of the constituents of natural wine are as follows:--The

extract (after deducting the free acids) ranges from 1·10 to 1·78

per cent.; the proportion of ash to extract varies from 1 : 19·2 to

1 : 6·4; that of phosphoric acid to ash ranges from 1 : 12·3 to 1 :

10·49; that of alcohol to glycerine, from 100 : 12·3 to 100 : 7·7.[110]

From the investigations of Dr. Dupré, it would appear that in genuine

unfortified wines, the amount of alcohol present varies from 6 to 12

per cent. by weight. A wine containing less than 6 per cent. would be

unpalatable, and more than 13 per cent. cannot well be present, since

natural grape-juice does not contain the quantity of sugar requisite

for the production of a greater amount of alcohol; moreover, an excess

of this proportion would retard, if not entirely stop, the process

of fermentation. Pure wines contain a greater proportion of volatile

than fixed ethers, but in fortified wines the reverse is frequently

the case. In natural wines, which are not over a few years old, the

sugar present rarely amounts to 1 per cent., generally it is much less.

Fortified wines, in which fermentation has been checked by the addition

of alcohol, often contain 5 per cent. of sugar; champagnes usually show

from 4 to 10 per cent., and, in some liqueur wines, a maximum of 25 per

cent. has been found. In natural wines, the total dry residue generally

ranges from 1·5 to 3 per cent., while in fortified wines the addition

of sugar and other substances may increase its proportion to 10 per

cent., or even more. At the Paris Municipal Laboratory the following

standards are adopted: The amount of added water in all wines, not

sold as of a special or abnormal character, is calculated on a basis

of 12 per cent. of alcohol (by volume) and 24 grammes of dry extract

per litre. The proportion of potassium sulphate in unplastered wines

must not exceed 0·583 gramme per litre. The use of salicylic acid is

prohibited.

FOOTNOTES:

[87] During the year 1886 the total production of Californian wine

approximated 19½ million gallons, of which 3½ million gallons were

consumed in the manufacture of brandy, and 5 million gallons exported.

[88] These figures denote the weight in grammes of the ingredients

contained in 100 c.c. of the wine; otherwise, percentages are expressed.

[89] Berichte der Deutsch. Chem. Gesell., 1885, p. 426.

[90] Zeit. f. Anal. Chem., 1885, p. 44.

[91] Repert. Anal. Chem., 1882, ii., p. 1.

[92] ‘Comptes Rendus,’ xcviii. p. 110.

[93] _Vide_ ‘Spon’s Encyclopædia.’

[94] Jay, Bullet. de la Soc. Chim., xlii. p. 217.

[95] Dict. des Falsifications.

[96] ‘Les Mondes, Revue Hebd. des Sciences,’ No. 4, 1876.

[97] Bullet. de la Soc. de Chim., xlii. pp. 167 and 207.

[98] Recent reports of the vintage in France for the year 1886,

indicate that, while a decided improvement has been experienced in the

Champagne, Burgundy, Hérault, and Rousillon districts, this has failed

to be the case in Charentes and Gironde, where the phylloxera has again

seriously injured the crops.

[99] F. Schaffer (Zeits. Anal. Chem., xxiv. p. 559) has made the

following analyses of artificial wine (grammes in 100 c.c.):--

------------------------+--------+--------+-------

Alcohol (by volume) | 8·05 | 9·55 | 7·02

Extract | 2·395 | 1·962 | 1·797

Sugar | 0·330 | 0·409 | 0·321

Ash | 0·209 | 0·135 | 0·160

Acidity (as tartaric) | 0·743 | 0·501 | 0·772

Free tartaric acid | -- | traces | traces

Cream of tartar | 0·264 | 0·227 | 0·471

Sulphuric anhydride | 0·0374 | -- | --

Phosphoric anhydride | 0·0196 | 0·0135 | 0·0172

------------------------+--------+--------+-------

[100] It is asserted by a prominent wine merchant in New York that the

monthly production of two manufacturers of artificial wine in this city

exceeds 30,000 gallons.

[101] Blyth, op. cit., p. 445.

[102] According to J. Carter Bell (‘Analyst,’ vi. pp. 197, 221), the

average composition of the ash of pure grape-juice is as follows:--

K_{2}O Na_{2}O CaO MgO Fe_{2}O_{3} & Al_{2}O_{3}

42·14 3·37 11·48 9·67 0·75

SiO_{2} P_{2}O_{6} SO_{3} Cl

0·29 9·60 9·14 1·09

[103] Curtman (Jour. Pharm., xiv. p. 523) states that salicylic acid

can be detected by adding to 4 c.c. of the wine (or beer) 2 c.c. of

methylic alcohol and 2 c.c. of sulphuric acid. Shake the mixture, heat

gently for two minutes, then allow to cool. Next heat to boiling,

when, in presence of the acid, the odour of oil of wintergreen will be

perceptible.

[104] Zeit. f. Anal. Chem., xxi. p. 3, 1882.

[105] Journ. Chem. Soc., xxxvii. p. 572.

[106] Schweizer Wochenschrift, xxii. p. 143.

[107] ‘Comptes Rendus,’ 101, pp. 823, 1011, 1167.

[108] Répert de Pharm. xii. p. 504.

[109] Reichsanzeiger, 1884, No. 154.

[110] R. Borgman (loc. cit.) gives the follow average relations of

ingredients in pure wine:--

Alcohol : glycerine = 100 : 10·5

Extract : acidity = 1000 : 16·6

Acidity : ash = 10 : 3·4

Ash : extractives = 1 : 11·2

Phosphoric acid : ash = 1 : 6·8

LIQUORS.

The ordinary forms of liquors (namely, whisky, rum, and gin), are

prepared by the distillation of alcoholic infusions. The process of

distillation is preceded either by the conversion of the amylaceous

constituents of grain, first into sugar, then into alcohol, or by the

fermentation of saccharine bodies into alcohol, or, as in the case of

brandy, it may be directly applied to a solution containing alcohol.

_Brandy._--When genuine, brandy is the product of the distillation

of various sorts of rich, light-coloured wines. The most esteemed

quality is prepared in the neighbourhood of Cognac, in the Deux

Charentes district, and in Armagnac; but numerous inferior grades are

manufactured in Rochelle and Bordeaux and in other parts of Southern

France, as well as in Spain and Portugal. In the United States, a

considerable quantity is produced by the distillation of California and

Ohio wine. The fermented marc and lees of grapes are also extensively

utilised in the manufacture of brandy. Most of the liquor known in

commerce under this name, however, is made from the spirit obtained

by the distillation of potatoes, corn, and other grains, which is

subsequently rectified, deodorised, and then suitably flavoured.

In France, the different grades of brandy are known as _eau-de-vie

supérieure_ (the best quality of Cognac); _eau-de-vie ordinaire_

(common, sp. gr. 0·9476); _eau-de-vie de marc_ (chiefly used for mixing

purposes); _eau-de-vie seconde_ (weak and inferior); _eau-de-vie à

preuve de Hollande_ (sp. gr. 0·941); _eau-de-vie à preuve d’huile_ (sp.

gr. 0·9185); _eau-de-vie forte_ (sp. gr. 0·8390); and _esprit-de-vin_

(sp. gr. 0·8610).

The characteristic taste and bouquet of the original wine are to a

considerable extent communicated to the resulting brandy, and upon

these qualities its value is greatly dependent. Many of the remarks

made in regard to the ageing, flavouring and blending of wines equally

apply to brandy, and need not be repeated in this place. When freshly

distilled, it is colourless, its amber tint being either due to the

casks in which it has been stored, or to added caramel. The normal

constituents of genuine brandy are water, alcohol (including small

amounts of butylic, propylic and amylic), various ethers (acetic,

oenanthic, butyric, and valerianic), aldehyde, acetic and tannic

acids, and traces of sugar and the oil of wine. The specific gravity

usually approximates 0·9300 (equivalent to 52 per cent. of alcohol by

volume), it may, however, range from 0·9134 to 0·9381 (from 60 to 48

per cent. of alcohol). Owing to the presence of acetic acid, genuine

brandy usually shows a slightly acid reaction. According to Blyth, the

constituents vary as follows:--total solids, from 1 to 1·5 per cent.;

ash, from ·04 to ·2 per cent.; acids (estimated as tartaric), from ·01

to ·05 per cent.; sugar from 0 to ·4 per cent. A partial examination of

brandy, by König,[111] furnished the following percentages:--specific

gravity, 0·8987; alcohol (by weight), 61·70; extract, 0·645; ash,

0·009. The ingredients found in twenty-five samples of brandy tested

for the New York State Board of Health varied as follows:--specific

gravity, 0·9297 to 0·9615; alcohol (by weight) from 25·39 to 42·96;

extract, from 0·025 to 1·795; ash, from 0·002 to 0·014.

The majority of these samples were certainly abnormal in composition.

Ordonneau[112] has quite recently determined by careful fractional

distillation the proportions of the more important constituents of

cognac brandy twenty-five years old, with the following results, the

quantities being stated in grammes per hectolitre:--aldehyde, 3;

ethylic acetate, 35; acetal, traces; normal propylic alcohol, 40;

normal butylic alcohol, 218·6; amylic alcohol, 83·8; hexylic alcohol,

0·6; heptylic alcohol, 1·5; propionic, butyric and caproic ethers, 3;

oenanthic ether, 4; amines, traces. The large proportions of normal

butylic and amylic alcohols obtained are very significant. It was found

that commercial alcohol, prepared from corn, potatoes and beetroot,

while containing isobutylic alcohol, was entirely free from normal

butylic alcohol, and the difference in flavour between genuine brandy

and brandy distilled from grains would appear to be mainly due to

this fact. Normal butylic alcohol is obtained when fermentation takes

place under the influence of elliptical or wine yeast, whereas the

iso-alcohol is the product of fermentation induced by means of beer

yeast; and it was shown that, by fermenting molasses, etc., with the

aid of wine yeast, a spirit was obtained which much resembled brandy in

colour and flavour.

_Whisky._--Whisky is the spirituous liquor prepared by distilling

fermented infusions of barley, wheat, corn, and other grains. Spirits

that contain over 60 per cent. of alcohol are known as “high wines,”

or common spirits; those containing 90 per cent. of alcohol are often

termed “cologne spirits,” the name whisky being usually given to the

product of a former distillation, containing about 50 per cent. by

weight of alcohol. In Great Britain, the largest amount of whisky is

made in Scotland and Ireland; in the United States, the principal

supply comes from the States of Illinois, Ohio, Indiana, Kentucky

(Bourbon Co.), and Pennsylvania (Monongahela Co.). The grains taken

differ greatly in composition. In Scotland and Ireland, malted barley

(pure, or mixed with other grain) is extensively employed; in the

preparation of Bourbon, partially malted corn and rye are taken,

while, for Monongahela whisky, only rye (with 10 per cent. of malt)

is used. The essential features of whisky-making are, first, the

conversion of the starch of the grain into dextrine and glucose,

which takes place in the process of _mashing_; the change being due

to the action of the nitrogenous principle, _diastase_ (formed during

the germination of the gain); then, the transformation of the sugar

into alcohol and carbonic acid by fermentation, which is induced by

the addition of yeast; and, finally, the concentration of the alcohol

by distillation. The quality of whisky is much affected by the nature

of the grain from which it is prepared, and by the care exercised in

its manufacture, more particularly in the process of distillation.

The most injurious ingredient in distilled spirits is commonly known

as “fusel oil,” which term comprises several products of alcoholic

fermentation, possessing a higher boiling point than ethylic alcohol,

and consisting chiefly of amylic alcohol, accompanied by small

proportions of butylic and propylic alcohols. Several varieties of

fusel oil exhibiting distinctive properties are met with, but that

obtained from potato-spirit is the most common. As a rule, the spirits

prepared from malted grain contain the smallest proportion. In the

manufacture of whisky, a danger of promoting the formation of fusel

oil is incurred by carrying on the distillation to the furthest

point, in order to obtain the greatest possible quantity of alcohol.

In Great Britain, the fermented mash is removed from the remaining

grain before its introduction into the still; but in this country the

entire mash is occasionally taken, by which means a larger yield of

alcohol is supposed to be effected. This practice is evidently open to

the objection that the solid matters of the wort are liable to suffer

destructive distillation, and engenders the formation of fusel oil.

Another result, sometimes experienced, is the imparting of a smoky

flavour to the product, which was originally intentionally communicated

to the famous “poteen” whisky of Ireland, by using malt dried by

means of burning turf. This quality is said to be still artificially

obtained by the use of creosote. Genuine whisky, when recently

made, is nearly colourless; but, if preserved in casks, it gradually

acquires a brownish colour. It contains minute quantities of tannic

acid, and ethylic and amylic acetates and valerianates. The specific

gravity generally ranges between 0·9220 and 0·9040, corresponding to

48 and 56 per cent. of alcohol. The solid extract in whisky is usually

below 1 per cent., and the total volatile acids under 0·1 per cent.

In regard to the average composition of whisky, chemical literature

furnishes but very meagre data. The examination of a large number of

samples of ordinary American whisky in 1881, for the New York State

Board of Health, gave the following results:--Specific gravity ranged

from 0·9018 to 0·9645; alcohol (by weight) from 23·75 to 52·58; solid

residue, from 0·100 to 0·752; ash, from 0·0020 to 0·0280. Several

samples of rye whisky, examined by Mr. Green,[113] showed alcohol (by

weight) from 32·50 to 51·20; tannic acid, 0·0003; acetic acid, 0·0012

to 0·002; sugar, 0·002 to 0·005; solid residue, 0·160 to 0·734.

_Rum._--Rum is obtained by the distillation of the fermented juice

of sugar-cane or of molasses; a very considerable proportion of the

article bearing this name is, however, made from grain spirit. In

France and Germany the mother-liquor remaining after the extraction

of beet-sugar, is utilised in the manufacture of a spirituous liquor

greatly resembling rum in properties. The characteristic odour and

taste of the liquor are mainly due to the presence of ethylic butyrate,

and are frequently factitiously communicated to its imitations by

the direct addition of this ether or of butyric acid. Grain spirit

is also sometimes treated with pineapples, which likewise impart the

distinctive flavour. Rum is chiefly produced in the West Indies, and

in North America. The specific gravity ranges from 0·874 to 0·926;

alcohol, from 50 to 70 per cent.; solid residue, from 0·7 to 1·50 per

cent; ash, under 0·10 per cent.[114]

The following are the results obtained by Berkhurts, from the analysis

of various samples of genuine and artificial Jamaica rum:[115]--

-----------------+----------+----------+---------+-------

| Specific |Alcohol by| Total |

Source. | Gravity. | Weight. | Solids. | Ash.

-----------------+----------+----------+---------+-------

London | 0·885 | 61·38 | 0·668 | 0·023

Glasgow | 0·875 | 61·38 | 4·800 | 0·089

Bremen | 0·875 | 74·07 | 0·568 | 0·031

Directly imported| 0·910 | 51·33 | 2·047 | 0·098

Artificial | .. | 38·94 | 0·469 | 0·033

Artificial | .. | 58·86 | 0·926 | 0·021

-----------------+----------+----------+---------+-------

The variations in the composition of commercial rum would seem to be so

great that little information of value concerning its authenticity is

to be derived from analyses of a general character.

_Gin._--Genuine Holland gin is a spirit prepared by the distillation

of fermented grain infusions (rye and malted barley), flavoured with

juniper berries, or oil of turpentine. Formerly the flavouring was

directly introduced into the still together with the mash, but the

more recent practice is to add salt, water, and juniper berries to

the distilled grain spirit, and then re-distil the mixture. Numerous

other aromatic substances are likewise employed in the manufacture of

gin, among which are coriander, cardamom, and caraway seeds, orris,

angelica, and calamus roots, cassia, bitter-almonds, sweet fennel, etc.

Cayenne pepper, sugar, and acetic acid, are said to be also frequently

added to gin. Gin doubtless possesses more of an artificial character

than any other spirit. It is safe to assert that the great bulk of the

drink sold under the name is simply grain-spirits flavoured with some

of the preceding aromatics. On the other hand, the flavouring agents

employed are not, as a rule, harmful in their effects, so that the

quality of the liquor is mainly dependent upon the extent to which the

spirits used have been rectified. It is difficult to define “pure

gin,” since, owing to its compound character, it varies in composition

according to the method of manufacture followed by each individual

distiller. The variations found from the examination of twenty-five

samples of the commercial article, tested by the New York State Board

of Health, were as follow:[116]--Specific gravity, from 0·9302 to

0·9694; alcohol (by weight), from 18·64 to 44·33; solid residue, from

0·018 to 0·772; ash, from 0·001 to 0·019.

_Adulteration of liquors._--Although it is notorious that the more

common varieties of spirituous liquors are sophisticated, the practices

resorted to are unfortunately usually of a character that does not

permit of positive detection, and, unless an actual adulteration, such

as the addition of some substance foreign to the genuine liquor, has

been made, a chemical examination alone is frequently inadequate to

distinguish between the true and the factitious article. In fact, the

ordinary physical qualities, such as odour and taste, are often of

greater service in determining the genuineness of distilled spirits

than more scientific tests. The most prevalent form of sophistication

with brandy, rum, and gin, is their artificial imitations; the direct

addition of substances deleterious to health being of comparatively

unfrequent occurrence. It is usual to employ a certain proportion of

the genuine liquor in the fabrication of its imitation. An apparent

objection to this species of adulteration is that grain spirits are

liable to be used as the basis of the fictitious product, which is

therefore apt to be contaminated with fusel oil, a compound producing

toxic effects in a proportion fifteen times greater than ordinary

ethylic alcohol.

In the United States, whisky is probably less subjected to serious

sophistication than other spirituous drinks. While the blending

of this liquor (i. e. the mixing of new and old grades) is almost

universally practised by the refiner, and while the retail dealer often

reduces its alcoholic strength by the addition of water, there is very

little ground for the belief that, in this country, whisky is subjected

to noxious admixture to any great extent.

A very large number of recipes have been published for the manufacture

of spurious liquors; the following are characteristic, and will

indicate their general nature:--

_For Brandy_:--

Cologne spirits (reduced to proof) 40 galls.

Oil of cognac 1/6 oz.

Burnt sugar colouring 1½ pint.

Tannin ¼ oz.

Brandy essence 1 part.

Alcohol 1000 parts.

Water 600 „

The compound known as “Brandy essence” consists of oil of grapes, 5

parts; acetic ether, 4 parts; tincture of allspice, 1 part; tincture of

galls, 3 parts; and alcohol, 100 parts. “Oil of cognac” is a mixture of

amylic alcohol and oenanthic ether.

According to M. Duplais, the best imitation of Cognac is the

following:--

Alcohol (85 per cent.) 54 litres.

Rum (good quality) 2 „

Syrup of raisins 3 „

Infusion of green walnut hulls 2 „

Infusion of the shells of bitter almonds 2 „

Catechu, in powder 15 grammes.

Balsam of tolu 6 „

Pure water 37 litres.

Mix and colour with caramel.

New Cognac, Montpellier, Saintonge, and other brandies are aged and

improved by adding to every 100 litres: old rum, 2 litres; old kirsch,

1-3/4 litres; infusion of green walnut hulls, 3/4 litre; syrup of

raisins, 2 litres.

A compound sold as “London Brandy Improver” consists of sugar syrup,

acetic ether and essence of cayenne, coloured with caramel.

_Whisky_:--

(Rye) Proof spirit 50 galls.

Pelargonic ether 2 oz.

Pear oil 1 „

Oil of wintergreen (dissolved in alcohol) 10 drops.

Acetic ether 4 oz.

Oil of cloves (dissolved in acetic ether) 4 drops.

(Scotch) Alcohol (95 per cent.) 46 galls.

Scotch whisky 8 „

Water 18 „

Honey (3 lbs. in 1½ gall. water)

Creosote 5 drops.

Acetic acid 2 oz.

Pelargonic ether 1 „

Ale 1 gall.

(Irish) Spirits 30 galls.

Irish whisky 5 „

Old ale ½ „

Creosote (dissolved in acetic acid) 4 drops.

Pelargonic ether 1 oz.

The preparation met with in commerce under the name of “pelargonic

ether” appears to be identical with oenanthic ether.

_Rum_:--

Rectified spirits 6 quarts.

Jamaica rum 22 „

Rum essence 1½ oz.

Vanilla essence 1/10 „

Water 2 quarts.

St. John’s bread 1½ oz.

Raisins 1½ „

Proof spirits 40 galls.

Rum essence ½ pint.

Sugar colouring ½ „

Sugar syrup 1 quart.

“Rum essence” is composed of butyric ether, 15 parts; acetic ether,

2 parts; vanilla tincture, 2 parts; essence of violets, 2 parts; and

alcohol, 90 parts.

_Gin_:--

Corn spirits 80 galls.

Oil of turpentine 1 pint.

Oil of juniper 8 oz.

Salt 21 lbs.

Water 35 galls.

Oil of caraway ½ oz.

Oil of sweet fennel ¼ „

Cardamoms 8 „

Distil over, 100 galls.

The chemical examination of distilled spirits is ordinarily limited

to a determination of the alcohol, solid residue, ash, and volatile

acids, coupled with special qualitative and quantitative tests for any

particular adulterants, the presence of which may be suspected.

(_a_) _Alcohol._--In properly distilled liquors, a fairly approximate

estimation of their alcoholic strength is effected by the specific

gravity determination, which is best made by means of the special

gravity bottle. In the case of spirituous liquors which contain

extractive matters, it is necessary to first separate the alcohol

present by the process of distillation, and then determine the density

of the distillate when made up to the volume originally taken. The

following table gives the percentages of alcohol by weight and by

volume, and of water by volume, for specific gravities at 15°.[117]

The percentages of alcohol in the table are calculated for the

temperature of 15°. The necessary correction for differences of

temperature at which the determination is made is obtained by

multiplying the number of degrees above or below 15°, by 0·4, and

adding the product to the percentage shown by the table, when the

temperature is lower than 15°, and deducting it when it is above.

Percentage of alcohol, by weight and by volume, and of water by

volume, for specific gravity at 15°; water at same temperature being

the unit:--

---------+-------------------------

| PERCENTAGE.

+---------+---------------

| By | By

| Weight. | Volume.

Specific +---------+------+--------

Gravity. | Alc. | Alc. | Water.

---------+---------+------+--------

1·0000 | 0· | 0 | 100·

0·9985 | 0·80 | 1 | 99·05

0·9970 | 1·60 | 2 | 98·11

0·9956 | 2·40 | 3 | 97·17

0·9942 | 3·20 | 4 | 96·24

0·9928 | 4·00 | 5 | 95·30

0·9915 | 4·81 | 6 | 94·38

0·9902 | 5·61 | 7 | 93·45

0·9890 | 6·43 | 8 | 92·54

0·9878 | 7·24 | 9 | 91·62

0·9867 | 8·06 | 10 | 90·72

0·9855 | 8·87 | 11 | 89·80

0·9844 | 9·69 | 12 | 88·90

0·9833 | 10·51 | 13 | 88·00

0·9822 | 11·33 | 14 | 87·09

0·9812 | 12·15 | 15 | 86·19

0·9801 | 12·98 | 16 | 85·29

0·9791 | 13·80 | 17 | 84·39

0·9781 | 14·63 | 18 | 83·50

0·9771 | 15·46 | 19 | 82·60

0·9761 | 16·29 | 20 | 81·71

0·9751 | 17·12 | 21 | 80·81

0·9741 | 17·96 | 22 | 79·92

0·9731 | 18·79 | 23 | 79·09

0·9721 | 19·63 | 24 | 78·13

0·9711 | 20·47 | 25 | 77·23

0·9700 | 21·31 | 26 | 76·33

0·9690 | 22·16 | 27 | 75·43

0·9679 | 23·00 | 28 | 74·53

0·9668 | 23·85 | 29 | 73·62

0·9657 | 24·70 | 30 | 72·72

0·9645 | 25·56 | 31 | 71·80

0·9633 | 26·41 | 32 | 70·89

0·9620 | 27·27 | 33 | 69·96

0·9607 | 28·14 | 34 | 69·04

0·9595 | 29·01 | 35 | 68·12

0·9582 | 29·88 | 36 | 67·20

0·9568 | 30·75 | 37 | 66·26

0·9553 | 31·63 | 38 | 65·32

0·9538 | 32·52 | 39 | 64·37

0·9522 | 33·40 | 40 | 63·42

0·9506 | 34·30 | 41 | 62·46

0·9490 | 35·18 | 42 | 61·50

0·9473 | 36·09 | 43 | 60·58

0·9456 | 37·00 | 44 | 59·54

0·9439 | 37·90 | 45 | 58·61

0·9421 | 38·82 | 46 | 57·64

0·9403 | 39·74 | 47 | 56·66

0·9385 | 40·66 | 48 | 55·68

0·9366 | 41·59 | 49 | 54·70

0·9348 | 42·53 | 50 | 53·72

0·9328 | 43·47 | 51 | 52·73

0·9308 | 44·41 | 52 | 51·74

0·9288 | 45·37 | 53 | 50·74

0·9267 | 46·33 | 54 | 49·74

0·9247 | 47·29 | 55 | 48·74

0·9226 | 48·26 | 56 | 47·73

0·9205 | 49·24 | 57 | 46·73

0·9183 | 50·21 | 58 | 45·72

0·9161 | 51·20 | 59 | 44·70

0·9139 | 52·20 | 60 | 43·68

0·9117 | 53·19 | 61 | 42·67

0·9095 | 54·20 | 62 | 41·65

0·9072 | 55·21 | 63 | 40·63

0·9049 | 56·23 | 64 | 39·60

0·9026 | 57·25 | 65 | 38·58

0·9002 | 58·29 | 66 | 37·54

0·8978 | 59·33 | 67 | 36·51

0·8954 | 60·38 | 68 | 35·47

0·8930 | 61·43 | 69 | 34·44

0·8905 | 62·50 | 70 | 33·39

0·8880 | 63·58 | 71 | 32·35

0·8855 | 64·64 | 72 | 31·30

0·8830 | 65·72 | 73 | 30·26

0·8804 | 66·82 | 74 | 29·20

0·8778 | 67·93 | 75 | 28·15

0·8752 | 69·04 | 76 | 27·09

0·8725 | 70·16 | 77 | 26·03

0·8698 | 71·30 | 78 | 24·96

0·8671 | 72·43 | 79 | 23·90

0·8644 | 73·59 | 80 | 22·83

0·8616 | 74·75 | 81 | 21·76

0·8588 | 75·91 | 82 | 20·68

0·8559 | 77·09 | 83 | 19·61

0·8530 | 78·29 | 84 | 18·52

0·8500 | 79·51 | 85 | 17·42

0·8470 | 80·72 | 86 | 16·32

0·8440 | 81·96 | 87 | 15·23

0·8409 | 83·22 | 88 | 14·12

0·8377 | 84·47 | 89 | 13·01

0·8344 | 85·74 | 90 | 11·88

0·8311 | 87·04 | 91 | 10·76

0·8277 | 88·37 | 92 | 9·62

0·8242 | 89·72 | 93 | 8·48

0·8206 | 91·08 | 94 | 7·32

0·8169 | 92·45 | 95 | 6·16

0·8130 | 93·89 | 96 | 4·97

0·8089 | 95·35 | 97 | 3·77

0·8046 | 96·83 | 98 | 2·54

0·8000 | 98·38 | 99 | 1·28

0·7951 | 100·00 | 100 | 0·00

---------+---------+------+--------

(_b_) _Solid residue._--This is determined by evaporating 100 c.c. of

the liquor in a tared platinum dish, until constant weight is obtained.

(_c_) _Ash._--The proportion of ash is found by the incineration of the

solid residue. If the presence of poisonous metallic adulterants (such

as copper or lead) is suspected, a further examination of the ash is

necessary.

(_d_) _Acids._--The acidity of distilled liquors is generally due to

minute quantities of acetic acid, and can be estimated by means of

1/10th normal soda solution.

Any mineral acid (_e.g._, sulphuric acid) supposed to be present is to

be sought for in the residue remaining, after the distillation process

employed in the determination of alcohol.

The presence of fusel oil in liquors is sometimes quite readily

detected, by first removing the ethylic alcohol by gentle evaporation,

and then inspecting the odour and taste of the still warm residue.

The suspected liquor may also be agitated with an equal volume of

ether, water added, and the ethereal stratum removed by means of a

pipette, and concentrated by evaporation; the residue is to be examined

for amylic alcohol. When distilled with a mixture of sulphuric and

acetic acids, amylic alcohol is converted into amylic acetate, which

may be recognised by its characteristic pear-like odour; or, the

amylic alcohol can be transformed into valerianic acid (which also

possesses a distinctive odour) by oxidation with sulphuric acid and

potassium dichromate. Another simple qualitative test for fusel oil

consists in first decolorising a small quantity of the liquor under

examination with animal charcoal, adding a few drops of hydrochloric

acid, and then a little freshly distilled and colourless aniline

oil, when, in presence of fusel oil, it will be observed that the

aniline compound acquires a perceptible rose tint as it falls to the

bottom of the liquid. The quantitative determination of fusel oil

presents some difficulties. A very ingenious method has been suggested

by Marquardt.[118] It consists essentially in first agitating the

sample with chloroform, draining off the solution obtained, washing

it by repeated shaking with water, and then treating it at 85° with a

mixture of 5 parts potassium dichromate, 2 parts sulphuric acid, and

30 parts of water. The valerianic acid thus formed is now separated

by distilling the mixture of water and chloroform. The distillate is

digested with barium carbonate, next concentrated by evaporation,

and then filtered, and divided into two equal portions. One portion

is evaporated to dryness, the residue taken up with water containing

a little nitric acid, and the amount of barium present determined

by precipitation with sulphuric acid. In the other portion, the

chlorine originating from a partial oxidation of the chloroform, is

to be estimated. The amount of barium combined with the chlorine, is

deducted from the total quantity obtained; the remainder represents the

proportion in combination with the fatty acids formed by oxidation. Of

these, valerianic acid largely predominates; and the amount of barium

valerianate [Ba_{2} (C_{2}H_{3}O_{2})] found is calculated to its

equivalent in amylic alcohol. Capsicum, creosote, etc., are isolated by

treating the sample with ether or benzole, and testing the odour and

taste of the evaporated solutions so prepared.

Creosote gives a blue colour with ferric chloride solution; and the

exceedingly pungent vapours evolved upon heating a residue containing

capsicum are equally characteristic. The presence of tannin in

distilled spirits, which is mostly derived from their preservation in

casks, is recognised by the formation of a bluish-black colour upon the

addition of ferric solutions. The identification of the various ethylic

and amylic ethers used in the preparation of factitious liquors is a

matter of some difficulty. Their presence is most readily detected by

means of their characteristic odour, which is developed upon adding a

little sodium hydroxide to the sample, evaporating the mixture over

the water-bath almost to dryness, and then adding a small quantity of

sulphuric acid. Another means of ascertaining the nature of the organic

ethers present in spirits is to first remove the ethylic alcohol

contained by a partial distillation with an alkaline solution, and

then acidulate the remaining liquid with sulphuric acid, and repeat

the distillation, when the volatile fatty acids originally contained

in the ethers will be found in the distillate; their identity is to be

established by means of their characteristic properties. Nitrous ether

(which compound is not contained in genuine liquors) may be detected

by partially distilling the sample and adding a mixture of potassium

iodide, starch paste, and acetic acid to the first portion of the

distillate, the production of a blue colour indicating its presence. As

previously remarked, the exercise of the ordinary senses is frequently

of greater value in judging the quality of liquors than the results of

chemical tests. Many of the organic ethers employed in the manufacture

of artificial liquors are identical with those contained in the genuine

article, and it is obvious that, in such instances, no distinction can

be made between them.

FOOTNOTES:

[111] ‘Nahrungs u. Genussmittel,’ 1st part, p. 187.

[112] ‘Comptes Rendus,’ 102, p. 217-219.

[113] Am. Chem. 1876, p. 46.

[114] Blyth, op. cit.

[115] ‘Wieder die Nahrungsfälscher,’ 1881, p. 105.

[116] See Report by Dr. F. E. Engelhardt, New York State Board of

Health, 1882.

[117] Hager’s ‘Untersuchungen.’

[118] ‘Berichte,’ 1882, pp. 1370, 1661.

WATER.

The subject of the purity of potable waters possesses the highest

degree of importance in its sanitary relations, and, particular

attention has been bestowed upon methods of analysis that would serve

to indicate the character and significance of existing impurities.

The earlier processes of examination, which chiefly consisted in the

determination of the mineral constituents of water, while of use in

furnishing an idea of the general nature of the water regarded as an

inorganic solution, almost totally failed to reveal the presence of the

more subtle and important organic contaminations which are now known

to exert an active influence in the propagation of zymotic diseases.

During the past few years, decided progress has been attained in the

analytical methods employed. Little is known of the exact nature of

the organic constituents present in water that has received sewage

contamination. They may be either of vegetable or animal origin, and it

appears to be very probable that they constitute organised germs. But,

although we are still unable to determine the constitution of these

deleterious ingredients, it is at present possible to approximately

ascertain the hygienic character of drinking water, and to distinguish,

with a fair degree of accuracy, between a good and a bad sample. In

arriving at a conclusion regarding the sanitary quality of water, it

is, however, also needful to take into consideration the origin and

surrounding conditions which affect the chances of contamination.

Most of the more recent methods of water analysis are based upon the

fact, that the putrefactive decomposition of harmful organic matter

is attended by the genesis of certain compounds (such as ammonia,

nitrites, and nitrates), of which quantitative estimations can be made.

For the purpose of ascertaining the character of a potable water, the

following determinations are usually necessary:--

1. Colour, odour, and taste.

2. Total solid matter and loss on ignition.

3. Organic matter in solution.

4. Chlorine.

5. Ammonia, free and albuminoid.

6. Nitrogen, as nitrites and nitrates.

Certain precautions should be observed in the collection of samples of

water intended for examination. It is indispensable for this purpose

to employ scrupulously clean glass stoppered bottles, which are washed

out several times with the water previous to being filled. If a well

or stream is to be sampled, the bottle should be entirely immersed in

the water some distance from the sides of the stream, and, if taken

from a pump or pipe, the latter should be cleansed by first running a

considerable quantity of the water before charging the bottle.

1. _Colour, odour, and taste._--The colour is best determined by

filling a glass cylinder, about 2 feet in height, with the sample,

placing it upon a white surface and observing the tint produced; or, by

the use of a coloured glass tube of the same length, which is provided

with glass plates attached at each end, and is filled with the sample

and viewed when held towards a sheet of white paper.

As a rule, pure water exhibits a light-bluish tint, a yellowish hue

being generally considered a suspicious indication; but it frequently

occurs that a perfectly colourless water is bad, and one possessing a

decided colour may prove to be at least, fair in quality. The odour of

the sample is ascertained by placing a corked bottle, one-half filled

with the water, in a warm place (at about 38°) for some time, and then

shaking the bottle, withdrawing the stopper and immediately testing the

odour. Pure water should be free from much perceptible odour of any

kind, and more especially from one of a disagreeable nature. The same

remark applies to the taste. Water should be practically tasteless,

even when warmed. It frequently happens, however, that a water may be

highly contaminated with deleterious organic impurities, and still

remain devoid of any marked unpleasant taste. There are few simple

tests of any value which will reveal at once the sanitary quality of

drinking water. One, sometimes employed, is to fill a clean quart

bottle about three-fourths full with the suspected sample, and dissolve

in it a teaspoonful of fine granulated white sugar. The bottle is

then corked and allowed to remain in a warm place for two days, when,

in the presence of sewage contamination, it will become cloudy or

milky.[119] According to Wanklyn and Chapman,[120] if a brownish colour

or precipitate is produced upon the addition of 1·5 c.c. of Nessler’s

reagent (see p. 208) to 100 c.c. of the water, it should be considered

unfit for domestic use.

2. _Total solid residue and loss on ignition._--500 c.c. of the water

under examination are introduced, in small portions at a time, into a

tared platinum dish, and evaporated to dryness over the water-bath, the

residue being subsequently dried for three or four hours in an air-bath

at 100°. The solid residue obtained, multiplied by 200, represents

parts in 100,000: or, by 140, grains per imperial gallon. It is usually

considered that, unless the proportion of total solids exceeds 40

grains per Imperial gallon (32 grains per U.S. gallon, or about 56·5

parts per 100,000), the water need not be objected to for drinking

purposes on this ground alone. The volatile and organic matters are

determined by igniting the solid residue, which is afterwards allowed

to cool. It is then moistened with a little carbonic acid water or

solution of ammonium carbonate, dried to constancy at 130°, and the

organic matter estimated by the decrease in weight. Formerly, this

process was chiefly depended upon for determining the proportion of

organic substances contained in water. It is open to numerous serious

objections, among which are, that it may afford a result either

below or above that correctly representing the quantity of organic

ingredients present in the sample. The first case takes place when

a portion of the organic matter is decomposed during the process of

evaporation, and is quite liable to occur; the second case takes place

when the water contains nitrates, which would be decomposed upon

ignition. The method, however, possesses some value, and is still often

resorted to as affording a general idea of the proportion of organic

contamination present, the degree of blackening of the solid residue

during the process of ignition being, at least, a useful qualitative

indication.

3. _Organic matter in solution._--A method frequently employed for

this determination is based upon the supposition that the amount of

potassium permanganate required to oxidise the organic constituents

contained in water would serve as a criterion of its sanitary value.

It is generally known as the “Forchammer” or “oxygen” process, and,

although of undoubted service in comparing the quality of samples of

very impure water, it is defective in the following important respects:

Different organic substances are not affected to an equal extent by

potassium permanganate; albumen, for instance, being far less easily

oxidised than other compounds, and the value of the results afforded is

vitiated by the presence of certain inorganic bodies, such as nitrites,

sulphuretted hydrogen, ferrous salts, etc. It has been stated, that

the more deleterious and putrescent organic ingredients of water are

those most readily affected by the permanganate solution. As modified

and improved by Miller[121] and by Tidy,[122] the process consists

substantially in adding an excess of a standard solution of potassium

permanganate to a measured quantity of the water under examination

(acidulated with sulphuric acid), and then determining the excess of

permanganate used by means of sodium hyposulphite and potassium iodide.

The following solutions are required:--

_Potassium Permanganate._--0·395 gramme of the salt is dissolved in

1 litre of distilled water; 10 c.c. of this solution represent 0·001

gramme of available oxygen.

_Sodium Hyposulphite._--One gramme of the salt is dissolved in a litre

of water.

_Starch solution._--One gramme of starch is triturated with about 20

c.c. of boiling water, and the mixture allowed to stand at rest over

night, after which the clear supernatant solution is drawn off.

_Pure distilled Water._--This is prepared by digesting 10 litres of

distilled water with 10 grammes of potassium hydroxide and 2 grammes of

potassium permanganate in a still provided with an inverted condenser

at 100° for twenty-four hours, after which the water is distilled,

separate portions being frequently tested with Nessler’s solution; the

distillate is not reserved for use until this reagent ceases to produce

a brownish coloration.

The determination proper is executed as follows:--Two flasks are first

thoroughly cleansed by washing with concentrated sulphuric acid, and

subsequently with water; 250 c.c. of the water to be examined are

introduced into one, and the same volume of the pure distilled water,

prepared as above, is placed in the other. 10 c.c. of dilute sulphuric

acid (1 part pure acid and 8 parts distilled water) and 10 c.c. of the

potassium permanganate solution are now added to each flask, both then

being put aside for three hours. Two drops of a 10 per cent. solution

of potassium iodide are next added to the flasks, and the amount of

iodine liberated (which is equivalent to the quantity of permanganate

unacted upon by the water) is determined by titration with the sodium

hyposulphite solution. The precise end of the reaction is ascertained

by means of a few drops of the starch paste, the hyposulphite being

added to each flask until the blue colour produced by the starch

disappears. The quantities of solution used in each titration are then

read off.

The amount of permanganate consumed is equal to A-B, where A represents

the hyposulphite used with the distilled water, and B, that used with

the sample under examination, and the proportion of oxygen which is

consumed by the water tested, can be calculated by the formula:--

((A - B) _a_) / A

in which _a_ is the available oxygen in the added permanganate. For

example, if 10 c.c. of permanganate (= 0·001 gramme available oxygen)

are added to the 250 c.c. (= ¼ litre) contained in each flask, and

the distilled water required 35 c.c., the sample 15 c.c., of the

hyposulphite solution, the proportion of oxygen consumed by the ¼ litre

of water, would be

((35 - 15) × ·001) / 35

= ·000571, which represents ·228 parts of oxygen in 100,000 parts of

water.

In applying the preceding test, it is requisite that the flasks should

be kept at a particular temperature, such as 27°. The presence of

putrescent and readily oxidised organic matter or nitrites, which

indicates dangerous contamination, is recognised by the absorption of

any considerable proportion of oxygen in the space of two minutes.

According to Dr. Tidy, 100,000 parts of water of various degrees of

purity, absorb the following amount of oxygen in three hours:--

Part Oxygen.

1. Great organic purity 0 to 0·05

2. Medium purity 0·05 „ 0·15

3. Doubtful 0·15 „ 0·21

4. Impure over 0·21

4. _Chlorine._--The importance attached to the estimation of chlorine

in potable waters is derived from the fact that this element enters

largely into the food of men and animals, and is thrown off in their

excreta. This, naturally, contributes to the sewage contamination to

which water is often exposed. Water, however, may take up a certain

proportion of chlorides from the geological strata through which it

passes, and it is of importance to bear this fact in mind in forming

a conclusion as to the significance of the results afforded by this

determination. It is, likewise, to be remembered that vegetable

organic pollution would escape detection were the quantity of chlorine

contained alone taken into consideration. The determination is

conveniently made as follows:--50 c.c. of the water are introduced

into a beaker, a drop or two of a concentrated and neutral solution

of potassium chromate added, and then a standard solution of silver

nitrate very cautiously added from a burette, drop by drop, until a

faint but permanent red tint is produced. If the silver solution is

prepared by dissolving 2·394 grammes of the nitrate in 1 litre of

distilled water, the number of c.c. required to cause the reddish

coloration directly indicates the parts of chlorine present in 100,000

parts of the water examined. According to Frankland, 100,000 parts

of water from various sources contain the following proportions of

chlorine:--

Rainwater 0·22

Upland surface water 1·13

Springs 2·49

Deep wells 5·11

Watts’ ‘Dictionary of Chemistry’ quotes the proportions below:--

Thames, at Kew 1·21

Thames, at London Bridge 6·36

Loch Katrine 0·56

Rhine, at Basle 0·15

Rhine, at Bonn 1·45

Lake of Geneva 0·67

Elbe, near Hamburg 3·94

Loire, at Orleans 0·29

The amount of chlorine contained in sewage is stated to range from 6·5

to 21·5 parts, the average being 11·54 parts.[123] It is generally

considered that a proportion in excess of 5 parts in 100,000 parts

of a drinking water, which is not liable to be affected by mineral

admixture, is to be ascribed to organic contamination.

5. _Ammonia, free and albuminoid._--It has already been mentioned

that the decomposition of the nitrogenous organic impurities present

in polluted water results in the production, first, of ammonia, then

of nitrites and nitrates, and, as it is commonly asserted that the

deleterious character of water is mainly due to the putrefactive

processes taking place, which are probably directly proportionate to

the quantity of ammonia produced, it is evident that the determination

of this compound is of considerable importance. The proportion of

albuminous and allied constituents in a sample can, moreover, be

measured by the quantity of ammonia produced when the water is boiled

with an alkaline solution of potassium permanganate. Upon the foregoing

facts, Messrs. Wanklyn, Chapman, and Smith[124] have based a method for

the determination of the sanitary quality of potable waters, which is

in very general use. It involves, first, an estimation of the ammonia

generated upon distilling the water with sodium carbonate (“free”

ammonia); second, the quantity given off by boiling with alkaline

potassium permanganate (“albuminoid” ammonia). In case the water tested

is contaminated with urea, which is not improbable, this compound will

be decomposed into ammonia by the treatment with sodium carbonate. The

following solutions are employed in the execution of the test:--

_Ammonium Chloride._--Dissolve 1·5735 grammes of the dry and pure salt

in 1 litre of distilled water. When required for use, dilute 100 c.c.

of the solution to 1 litre; 1 c.c. of this diluted solution contains

·00005 gramme of NH_{3}.

_Pure Sodium Carbonate._--The ordinary pure reagent is freed from any

ammonia possibly contained by heating it in a platinum capsule.

_Pure distilled Water._--This is obtained as directed on p. 204.

_Nessler’s Reagent._--This is a strong alkaline solution of mercury

biniodide. It may be prepared by first dissolving 62·5 grammes of

potassium iodide in 250 c.c. of hot distilled water (reserving 10

c.c. of the solution), and adding a concentrated solution of mercury

bichloride, with constant shaking, to the remainder, until a permanent

precipitate remains undissolved; this is then brought in solution by

means of the 10 c.c. of iodide solution, set aside, and the addition of

mercury bichloride is carefully continued until a slight precipitate

reappears. A concentrated solution of potassium hydroxide (200 grammes

dissolved in water) is now added, and the volume of the whole made

up with distilled water to 1 litre. The solution is then allowed to

subside, after which it is decanted and preserved in a well-stoppered

bottle.

_Permanganate solution._--Dissolve 8 grammes of potassium permanganate

and 200 grammes of potassium hydroxide in 1 litre of water, and boil to

expel any ammonia present.

The estimation of free and albuminoid ammonia is made as follows:--100

c.c. of the water to be examined are introduced into a glass retort,

which connects with a Liebig’s condenser, and has previously been

thoroughly cleansed by boiling with distilled water; one gramme of

pure sodium carbonate is added, and the water distilled until 40 c.c.

have passed over, the distillate being separately collected in four

10 c.c. cylinders or tubes. About 10 c.c. of the alkaline solution of

potassium permanganate is then added to the remaining contents of the

retort, and the distillation continued almost to dryness. The second

distillate is likewise collected in fractions of 10 c.c. each. It

is advisable to so regulate the process of distillation, that only

about 10 c.c. pass over in the space of eight minutes. The two sets

of distillates are then separately tested by adding 0·5 c.c. of the

Nessler solution to each cylinder, well stirring the mixture, and

setting it aside for at least five minutes. A series of comparison

tubes (10 c.c. in capacity) are prepared by adding ·001, ·003, ·005 up

to ·01 gramme of ammonium chloride, and filling to the 10 c.c. mark

with pure distilled water; 0·5 c.c. of the Nessler reagent being added

to each. The degree of coloration exhibited in the cylinders containing

the two sets of distillates is then matched by the comparison cylinders.

It is evident, that from the data thus obtained, the amount of ammonia

obtained by the first distillation with sodium carbonate (free

ammonia), and by the second distillation with alkaline potassium

permanganate (albuminoid ammonia), can be determined. It has been

previously mentioned that urea evolves ammonia when boiled with sodium

carbonate; the amount of ammonia obtained by the first process of

distillation will therefore include that actually contained as such

in the water, and that generated by the decomposition of any urea

possibly present. As the presence of this body is incompatible with

a good drinking water, this fact is of little real importance. In

case, however, it be desired to make an estimation of the free ammonia

really present, 500 c.c. of the water to be tested are treated with 1

or 2 c.c. of calcium chloride solution, then with a slight excess of

potassium hydroxide, and the liquid filtered. It is next distilled as

directed above, and the remaining contents of the retort made up to 500

c.c. 200 c.c. of the original sample are then subjected to the same

treatment with calcium chloride and potassium hydroxide, and filtered.

The second solution, which contains all the ammonia originally present

in the water, is now tested with Nessler’s reagent, the solution first

obtained by diluting the contents of the retort being employed, instead

of pure distilled water, for comparison.

The proportions of free and albuminoid ammonia found in the preceding

operations are usually expressed in parts per 100,000 of the water.

Wanklyn gives the following amounts of free and albuminoid ammonia

contained in 100,000 parts of several kinds of water:--

Deep spring water not over 0·001

„ „ „ mixed with surface water 0·005

Filtered water 0·005 to 0·010

Imperfectly filtered water 0·01 „ 0·02

Sewage 0·30

The same authority makes the following classification of potable water,

reference being made to parts of albuminoid ammonia present in 100,000

parts:--

Extraordinary purity 0 to 0·005

Satisfactory purity 0·005 „ 0·010

Dirty over 0·010

The presence of any considerable proportion of free ammonia is

usually indicative of recent sewage contamination. In the absence

of free ammonia, a water need not be rejected unless the albuminoid

ammonia exceeds 0·010 part, but a water containing over 0·015 part of

albuminoid ammonia should be condemned under all circumstances.

6. _Nitrogen as nitrites and nitrates._--It is quite generally accepted

that the presence in water of the oxidation products of nitrogen,

is to be ascribed to the oxidation of nitrogenous organic matter,

unless they are the result of percolation through soil containing

nitrates, and, for this reason, considerable importance attaches to

the quantitative estimation of the nitrogen present in the state of

nitrates, and, in some cases, nitrites. One of the most reliable

methods for this determination is the eudiometric process of Frankland,

which is based upon that of Crum,[125] and consists in agitating

the concentrated water with mercury and strong sulphuric acid, and

measuring the volume of nitric oxide formed by the reduction of

nitrates and nitrites. Owing, however, to the necessity of employing

gas apparatus, this method is not in very general use. Wanklyn’s

process is the following:--100 c.c. of the sample are made alkaline

with pure sodium hydroxide, evaporated to about one-fourth of its

original volume, next made up to 100 c.c. by adding pure distilled

water, and introduced into a flask which connects with a U-tube

filled with powdered glass moistened with hydrochloric acid. A piece

of aluminium foil is then added to the contents of the flask, and

the mixture is allowed to stand at rest for six or seven hours. The

contents of the U-tube are now transferred to the flask, the latter

is connected with a Liebig’s condenser and the liquid distilled. The

proportion of ammonia contained in the distillate is determined by

Nessler’s reagent as previously described, from which the amount of

nitrogen present as nitrates and nitrites is calculated.

Griess[126] has suggested a very useful process for the determination

of nitrous acid and nitrites in potable waters. It is executed by

placing 100 c.c. of the filtered water in a glass cylinder, and adding

a few drops of dilute hydrochloric acid, and 1 c.c. of a solution of

sulphanilic acid and naphthylamine hydrochloride. In the presence

of nitrites, a beautiful rose-red colour (due to the formation of

azobenzol-naphthylamine sulphonic acid), will be produced. The

proportion of nitrites contained in the water, is ascertained by

simultaneously subjecting a solution of potassium nitrite, of known

strength, to the same treatment, and matching the degree of colour

obtained, as in the Nessler process. This solution can be prepared by

dissolving 0·406 gramme of dry silver nitrite in hot water, and adding

a slight excess of potassium chloride. After cooling, the solution is

made up to one litre, the silver chloride allowed to settle, and the

clear liquid filtered. If 100 c.c. of the filtrate are further diluted

to one litre, each c.c. will contain 0·00001 gramme of nitrous acid.

In Ditmar’s method, the residue obtained by the evaporation of the

water, is first mixed with pure sodium hydroxide, and placed in a

small silver boat. It is next introduced into a combustion tube and

burned in a current of hydrogen, the evolved gases being received in an

absorption apparatus filled with very dilute hydrochloric acid. In this

method the amount of ammonia formed, is likewise estimated by means of

Nessler’s solution. The proportion of _organic nitrogen_ is found by

deducting the free ammonia present in the water and multiplying the

remainder by 14/17.

Messrs. Dupré and Hake[127] determine the _organic carbon_ in water

essentially as follows:--The residue of the evaporation of the water

is obtained in a very thin silver dish, which can be rolled up

and introduced into a combustion tube filled three-fourths of its

length with cupric oxide. The residue is then burned in a stream of

oxygen. The evolved carbonic acid is absorbed in a solution of barium

hydroxide, the precipitate formed being collected upon a filter,

washed, dried, and weighed; its weight, divided by 19·4, gives the

amount of organic carbon present in the sample. The carbonates and

nitrates originally contained in the water can be removed by boiling

with a saturated solution of sulphurous acid before the preliminary

evaporation.

Frankland gives the following average proportions of nitrogen, as

nitrates, occurring in 100,000 parts of various kinds of water:--

Rain water 0·007

Upland surface water 0·009

Deep wells and springs 0·400

Surface water (cultivated districts) 0·250

Shallow wells (no average), 2 to 5 parts common.

Other authorities regard the presence of more than 0·6 part of nitrogen

as nitrates per 100,000 parts of water as indicating dangerous

pollution.

At the International Pharmaceutical Congress held in Brussels,[128] the

following standards of purity for potable water were recommended:--

1st. A water should be limpid, transparent, colourless, without smell,

and free of matter in suspension.

2nd. It should be fresh, with a pleasant taste, and its temperature

should not vary much, and certainly not be higher than 15°.

3rd. It should not contain noxious animal or vegetable matter, and

especially none of these substances in a state of decomposition.

4th. It should not contain more than 6 to 10 mgrms. of organic matter

per litre, expressed in terms of oxalic acid. It should not contain

nitrogenous matter.

5th. The nitrogenous organic matter, oxidised with an alkaline solution

of potassium permanganate, should not yield more than 0·01 part of

albuminoid ammonia per 100,000.

6th. It should not assume a disagreeable smell after having been kept

in an open or closed vessel.

7th. It should not contain white algæ, nor numerous infusoria,

bacteria, etc.

8th. It must hold air in solution, which should contain a larger

proportion of oxygen than ordinary air.

9th. It should not contain, per litre, more than:--

0·5 gramme mineral salts.

·060 „ sulphuric anhydride.

·008 „ chlorine.

·002 „ nitric anhydride.

·200 „ alkaline earths.

·030 „ silica.

·003 „ iron.

In the Municipal Laboratory of Paris, the following standards for

potable waters are employed. One litre must not contain more than:--

0·5 to 0·6 gramme total mineral residue.

0·25 „ „ calcium sulphate.

0·015 „ „ chlorine.

0·005 „ „ organic matter (calculated as oxalic acid).

0·001 „ „ albuminoid ammonia.

0·001 „ „ metals precipitated by sulphuretted hydrogen.

0·003 „ „ iron.

No sulphuretted hydrogen.

100 c.c. should contain 3·25 c.c. of gas, 10 per cent. of which should

be carbonic acid and 33-1/3 per cent. oxygen.

Professor J. W. Mallet[129] suggests the idea, that the noxious

character of potable waters containing nitrates and nitrites, with but

small proportions of organic matter, may be due to the presence of a

special nitrifying ferment belonging to the lower organisms, which are

capable of propagating disease.

In regard to the degree of importance that should attach to definite

and arbitrary standards of purity, it appears to be accepted that,

although the data afforded as the result of chemical tests are often

of value in discriminating between pure and impure waters, but little

reliance should be placed upon such criteria alone.

Professor Mallet, who has devoted much attention to the investigation

of potable waters, and whose opinion on this subject is entitled to the

highest consideration, arrived at the following conclusions concerning

the more vital points at issue in the determination of the hygienic

character of water:--

“1. It is not possible to decide absolutely upon the wholesomeness

or unwholesomeness of a drinking water by the mere use of any of

the processes examined for the estimation of organic matter or its

constituents.

“2. I would even go further, and say that in judging the sanitary

character of the water, not only must such processes be used in

conjunction with the investigation of other evidence of a more general

sort, as to the source and history of the water, but should even be

deemed of secondary importance in weighing the reasons for accepting or

rejecting a water not manifestly unfit for drinking on other grounds.

“3. There are no sound grounds on which to establish such general

‘standards of purity’ as have been proposed, looking to exact amounts

of ‘organic carbon’ or ‘nitrogen,’ ‘albuminoid-ammonia,’ ‘oxygen of

permanganate consumed,’ etc., as permissible or not.

“4. Two entirely legitimate directions seem to be open for the useful

examination by chemical means of the organic constituents of drinking

water, namely; first, the detection of _very gross_ pollution, * * * *

and, secondly, the periodical examination of a water supply, as of a

great city, in order that the normal or usual character of the water

having been previously ascertained, any suspicious changes, which from

time to time may occur, shall be promptly detected and their cause

investigated.”

The microscopic and biological investigations of water are useful

adjuncts to the chemical examination. The former is made by

allowing a litre or more of the sample to remain at rest for several

hours, collecting the deposit formed and inspecting it by means of

the microscope, using low magnifying power at first. It will be

found advantageous to stain portions of the sediment obtained with

aniline violet, which, by a sort of predilection, attaches itself to

particular forms of vegetable and animal life, thereby rendering them

more distinct. The matters most usually observed in the microscopic

examination of the deposit are:--

1st. Numerous lifeless substances, such as mineral matters, vegetable

_debris_, muscular and cellular tissues, hairs, hemp, wool, cotton,

silk, starch cells, insect remains, and pollen grains.

2nd. Living vegetable forms, such as confervæ, various algæ,

oscillatoria, desmids, diatoms, and bacteria.

3rd. Living animal forms, including many varieties of infusoria and

animalcula. Of the latter, those known as “saprophytes” are regarded as

specially indicating the presence of sewage contamination.

Certain varieties of bacteria have been found associated with some

forms of disease, and particular attention has been bestowed upon the

study of these germs. The biological examination of water consists

of pathological experiments on living animals, made by injecting a

solution of the water-residue beneath the skins of rabbits, etc., and

of experiments made by inoculating culture gelatine with the water.

Of the latter methods of examination, that originally suggested by

Dr. Koch, of Berlin, and described by Dr. Percy F. Frankland,[130] is

well worthy of mention. In this process, the lower forms of life are

cultivated in a solid medium, by means of which the growth of each

colony is localised and rendered suitable for microscopic inspection.

The medium employed by Dr. Frankland has the following composition:

Lean meat 1 lb.

Gelatine 150 grammes.

Solid peptone 10 „

Sodium chloride 1 „

Distilled water 1 litre.

The finely-cut meat is first infused in half a litre of cold water

for two hours and strained; the gelatine is digested in the other

half-litre of water, then mixed with the meat-extract, and the whole

heated until the gelatine is completely dissolved, when the peptone and

salt are added.

The liquid is now cautiously neutralised with sodium carbonate, and

clarified by beating it together with two or three eggs, boiling,

straining through cloth, and filtering hot through bibulous paper;

upon cooling it sets to a transparent jelly. Before setting, 7 c.c. of

the liquid are introduced into a series of clean test-tubes, which are

tightly plugged with cotton-wool and then sterilised by steaming them

half-an-hour for three or four consecutive days. It is necessary to

observe special precautions in the collection of the sample of water to

be examined. Glass-stoppered bottles are well adapted for this purpose.

These are to be very thoroughly washed with distilled water, then dried

and finally sterilised by heating in an air-bath for three or four

hours at a temperature of from 150° to 180°.

The actual examination of the water is executed by first heating one of

the test-tubes containing the sterilised gelatin medium in a water-bath

to 30°, by which it is fused. The external portion of the cotton-wool

is next burned, the tube opened, and a certain number of drops of the

water to be tested (previously well shaken) are introduced by means

of a sterilised pipette. The mixture is immediately poured out upon a

clean and sterilised glass plate which rests in a perfectly horizontal

position, and is covered by a glass shade. The plate is supported

by a glass tripod which dips into a dish containing a two per cent.

solution of mercuric chloride--thus forming an antiseptic protection

from the external air. The tripods, dishes, etc., are sterilised

by washing them with the mercuric chloride solution. As soon as the

gelatine mixture has set, the glass plate (together with the cover)

is introduced into an air-bath kept at a temperature of from 20°-25°,

where it is allowed to remain for two to five days for incubation. The

individual organisms and the progress of the formation of colonies are

observed from time to time by inspecting the plate, which can be done

without removing the glass cover. As soon as they have become easily

visible to the naked eye, the plate is removed from the bath, and

placed upon another glass plate, which is ruled in squares, and put

over a black paper. The colonies are then counted by aid of a lens, or,

if they are too numerous to admit of this, the number contained in a

few of the squares is determined and multiplied accordingly.

Dr. Frankland has applied the foregoing method to the examination of

the London water supply (1885), with the following results:--

MICRO-ORGANISMS IN 1 C.C.

--------------+-----+-----+------+-----+----------+------+-----+-----

|Jan. | Feb.|March.| May.| June. | Sept.| Oct.| Nov.

--------------+-----+-----+------+-----+-----+----+------+-----+-----

River Thames | .. | .. | .. | .. | 155 | .. | 1644 | 714 |1866

at Hampton | | | | | | | | |

| | | | | | | | |

Chelsea | 8 | 23 | 10 | 14 | 22 | 81 | 13 | 34 | 3

| | | | | | | | |

West Middlesex| 2 | 16 | 7 | 3 | .. | 26 | 2 | 2 | 5

| | | | | | | | |

Southwark | 13 | 26 | 246 | 24 | .. | 47 | 18 | 24 | 32

| | | | | | | | |

Grand Junction| 382 | 57 | 28 | 3 | 21 | 18 | 43 | 40 | 40

| | | | | | | | |

Lambeth | 10 | 5 | 69 | 30 | .. | 38 | 103 | 26 | 26

| | | | | | | | |

RIVER LEA. | | | | | | | | |

| | | | | | | | |

River Lea at | .. | .. | .. | .. | .. | .. | .. | .. | 954

Chingford Mill| | | | | | | | |

| | | | | | | | |

New River | 7 | 7 | 95 | 3 | .. | 27 | 3 | 2 | 11

| | | | | | | | |

East London | 25 | 39 | 17 | 121 | .. | 22 | 29 | 53 | 14

| | | | | | | | |

DEEP WELLS. | | | | | | | | |

| | | | | | | | |

Kent (well at | .. | .. | .. | .. | 6 | .. | .. | 6 | 8

Deptford) | | | | | | | | |

| | | | | | | | |

Kent (supply) | 10 | 41 | 9 | 20 | 26 | .. | 14 | 18 | ..

--------------+-----+-----+------+-----+-----+----+------+-----+----

PLATE XI.

[Illustration: FIG. 2.]

[Illustration: FIG. 1.]

In Plate XI., Fig. 1 exhibits the animal and vegetable living forms

contained in Croton water. They have been catalogued as follows:--

(_a_) Asterionella formosa, vegetable; a diatom, × 312.

(_b_) Pediastrum simplex, vegetable; a desmid, × 200.

(_c_) Cyclotella astræa, vegetable; a diatom, × 200.

(_d_) Vorticella; an animalcule, × 312.

(_e_) Conferva, vegetable; “green scum,” × 40.

(_f_) Epithelial cell; × 200.

(_g_) Fragillaria cupucina, vegetable; a diatom, × 200.

(_h_) Heteromita ovata; an animalcule, × 500.

(_i_) Halteria grandinella (?); an animalcule, × 200.

(_k_) Anguillula fluviatilis; a water-worm, × 312.

(_l_) Amœba porrecta; an animalcule, × 200.

(_n_) Dinophrys; an animalcule, × 200.

(_o_) Didymoprium borreri, vegetable; a desmid, × 200.

(_p_) Tabellaria fenestrata, vegetable; a diatom, × 312.

(_q_) Free vorticella; an animalcule, × 200.

(_r_) Coccudina costata, dividing; an animalcule, × 312.

(_s_) Monas umbra; an animalcule, × 312.

(_t_) Cyclidium obscissum; an animalcule, × 312.

(_u_) Chilodon cucullulus; an animalcule, × 200.

(_v_) Epistylis nutans; young animalcules, × 200.

(_w_) Paramecium; an animalcule, × 200.

(_x_) Difflugia striolata, the lorica or case; an animalcule, × 200.

(_y_) Conferva; vegetable “green scum,” × 312.

(_z_) Vorticella microstoma; an animalcule, × 200.

(_aa_) Fragments of dyed wood, × 200.

(_cc_) Gomphonema acuminatum, vegetable; a diatom, × 200.

(_ee_) Arthrodesmus octocornis, vegetable; a desmid, × 312.

(_ff_) Scenodesmus quadricauda, vegetable; a desmid, × 200.

(_ii_) Navicula rhynchocephala (?), vegetable; a diatom, × 200.

Fig. 2 represents the organisms found in the Brooklyn (Ridgwood) water

supply:--

(_a_) Actinophrys sol; an animalcule, × 200.

(_b_) Coccudina costata; an animalcule, × 200.

(_c_) Chætonotus squamatus; hairy-backed animalcule, × 200.

(_d_) Notommata; a rotiferous animalcule, × 200.

(_e_) Amœba guttula; an animalcule, × 200.

(_f_) Melosira orichalaea, vegetable; a diatom, × 200.

(_g_) Vorticella microstoma; animalcules, × 200.

(_h_) Chætonotus larus; hairy-backed animalcule, × 200.

(_i_) Tabellaria flocculosa, vegetable; a diatom, × 200.

The original drawings from which Plate XI. is taken were prepared by

Mr. William B. Lewis, for the Metropolitan Board of Health.

The presence of these organisms, however startling some of them may

be in appearance, is usually not objectionable; indeed, microscopic

vegetable growths are frequently of service in the purification of

potable water. The more important forms of bacteria (bacilli, etc.),

present minute rod-like shapes, far less impressive in appearance.

Considerable difference of opinion exists in regard to the sanitary

value of the results afforded by the biological examination of water.

While the number of bacteria found in a given quantity of water

may be of aid in the formation of an opinion as to its relative

safety for domestic purposes, it should be borne in mind that these

micro-organisms are almost omnipresent, being contained in the air, and

in soils, and articles of food.

The following tabulation shows the relative purity of the water supply

of several American cities, as determined by Prof. A. R. Leeds, in

June, 1881:--

----------+-------+-------------------------------------------------------

| New |Brooklyn.

| York. | +-------+---------------------------------------

| | |Jersey |Philadelphia.

| | | City. | +-------+-----------------------

Parts in | | | | |Boston.|Washington.

100,000 | | | | | | +---------------

| | | | | | |Rochester.

| | | | | | | +-----------

| | | | | | | |Cincinnati.

| | | | | | | +---+

| | | | | | | |

----------+-------+-------+-------+-------+-------+-------+-------+-------

Free | | | | | | | |

ammonia. | 0·0027|0·00075|0·00475| 0·001 |0·01325| 0·006 | 0·0114| 0·0115

Albuminoid| | | | | | | |

ammonia. | 0·027 |0·00825|0·0427 | 0·018 |0·0605 | 0·027 | 0·023 | 0·024

Oxygen | | | | | | | |

required.| 0·81 |0·413 |0·95 | 0·46 |1·77 | 0·600 | 0·790 | 0·860

Nitrites. | None |None | None | None | None | None | None | None

Nitrates. | 0·8325|1·2025 |0·9065 | 0·6845|1·2395 | 0·8325| 0·629 | 0·740

Chlorine. | 0·350 |0·550 |0·235 | 0·3000|0·315 | 0·270 | 0·195 | 0·805

Total | | | | | | | |

hardness.| 3·300 |2·270 |3·200 | 4·400 |2·100 | 4·800 | 5·500 | 6·400

Total | | | | | | | |

solids. |11·800 |6·000 |9·300 |14·300 |8·500 |11·500 |10·000 |16·200

Mineral | | | | | | | |

matter. | 5·000 |5·000 |3·400 | 6·000 |2·000 | 5·500 | 4·000 | 9·000

Organic | | | | | | | |

and | | | | | | | |

volatile | | | | | | | |

matter. | 6·800 |1·000 |5·900 | 8·300 |6·500 | 6·000 | 6·000 | 7·200

----------+-------+-------+-------+-------+-------+-------+-------+-------

-----------------+-------+--------------+--------------+--------------

Parts per | April.| May. | June. | July.

100,000. +-------+-------+------+------+-------+-------+------

| 3rd. | 6th. | 26th.| 13th.| 30th. | 15th. | 30th.

-----------------+-------+-------+------+------+-------+-------+------

Appearance, &c. | Cl. |Sl. Tb.| Tb. | Cl. | Cl. | Cl. | Cl.

Odour (heated to | None | None | None | None | None | None | None

100° Fahr.). | | | | | | |

Chlorine in |0·278 |0·348 |0·244 |0·348 |0·226 |0·279 |0·226

chlorides. | | | | | | |

Equivalent to |0·459 |0·575 |0·400 |0·574 |0·374 |0·459 |0·374

sodium | | | | | | |

chloride. | | | | | | |

Phosphates. | None | None | None | None | None | None | None

Nitrites. | None | None | None | None | None | None | None

Nitrogen in | 0·0403|0·0494 |0·034 |0·0469|0·0371 |0·0395 |0·0387

nitrates and | | | | | | |

nitrites. | | | | | | |

Free ammonia. | 0·001 |0 |0·002 |0·003 |0·0005 |0·002 |0·003

Albuminoid | 0·009 |0·0166 |0·0086|0·007 |0·014 |0·008 |0·011

ammonia. | | | | | | |

“Hardness” | | | | | | |

equivalent | | | | | | |

to carbonate of | | | | | | |

lime-- | | | | | | |

Before boiling.| 4·73 |4·082 |4·280 |3·860 |4·968 |4·268 |4·332

After boiling. | 4·31 |3·787 |3·510 |3·500 |4·586 |4·268 |4·332

Organic and | 6·00 |1·500 |3·00 |2·50 |2·00 |0·50 |2·50

volatile | | | | | | |

(loss on | | | | | | |

ignition). | | | | | | |

Mineral matter | 5·00 |4·000 |4·50 |4·50 |5·50 |5·00 |5·00

(non volatile). | | | | | | |

Total solids (by |11·00 |5·50 |7·50 |7·00 |7·50 |5·50 |7·50

evaporation). | | | | | | |

-----------------+-------+-------+------+------+-------+-------+------

-----------------+-------------+------------+-----------+------+------

Parts per | August. | September. | October. | Nov. | Dec.

100,000. +------+------+-----+------+-----+-----+------+------

| 19th.| 31st.|15th.| 29th.|14th.|30th.| 15th.| 1st.

-----------------+------+------+-----+------+-----|-----+------+------

Appearance, &c. | Cl. | Cl. | Cl. | Cl. | Cl. | Cl. | Cl. | Cl.

Odour (heated to | None | None |None | None |None |None | None | None

100° Fahr.). | | | | | | | |

Chlorine in |0·278 |0·313 |0·209|0·208 |0·272|0·243|0·312 |0·295

chlorides. | | | | | | | |

Equivalent to |0·459 |0·517 |0·344|0·343 |0·458|0·400|0·515 |0·486

sodium | | | | | | | |

chloride. | | | | | | | |

Phosphates. | None | None | None| None |None |None | None | None

Nitrites. | None | None | None| None |None |None | None | None

Nitrogen in |0·0469|0·0486|0·037|0·0477|0·041|0·047|0·048 | ..

nitrates and | | | | | | | |

nitrites. | | | | | | | |

Free ammonia. |0·003 |0·001 |0·004|0·002 |0 |0·003|0·001 |0·0032

Albuminoid |0·014 |0·009 |0·016|0·0094|0·013|0·015|0·014 | ..

ammonia. | | | | | | | |

“Hardness” | | | | | | | |

equivalent | | | | | | | |

to carbonate of | | | | | | | |

lime-- | | | | | | | |

Before boiling.|4·586 |4·332 |5·096|3·949 |4·520|4·512|3·840 |3·729

After boiling. |3·949 |4·332 |4·459|3·822 |4·294|4·512|3·390 |3·164

Organic and |3·00 |2·00 |2·50 |2·50 |2·50 |3·00 |3·00 | ..

volatile | | | | | | | |

(loss on | | | | | | | |

ignition). | | | | | | | |

Mineral matter |5·00 |4·50 |4·00 |4·00 |4·00 |4·50 |4·00 | ..

(non volatile). | | | | | | | |

Total solids (by |8·00 |6·50 |6·50 |6·50 |6·50 |7·50 |7·00 | ..

evaporation). | | | | | | | |

-----------------+------+------+-----+------+-----+-----+------+------

Cl. signifies _clear_. Sl. Tb., _slightly turbid_.

Tb., _turbidity_ somewhat more marked.

PARTS PER 100,000.

--------------+-------+-----------------------+------------+----------

| | | Chlorine |

| | | in |Equivalent

| Date | Time when drawn. | Chlorides.| to

Description | when | +-----------------+----------+ | Sodium

of Sample. | taken | | |Odour when| | Chloride.

| | | Appearance in | heated | +----+

| | | two-foot Tube. | to 38°. | |

--------------+-------+-----+-----------------+----------+------+-----

| 1884. | | | | |

Mohawk River, |Dec. 5 | .. |Turbid, |Faint |0·233 |0·371

above Diamond| | | greenish yellow| aromatic | |

Woollen Mills| | | | | |

Hudson River, |Nov. 12| .. |Faintly turbid, |Faint, |0·233 |0·371

above | | | light greenish | vegetable| |

Lansingburg | | | yellow | | |

Troy hydrant | „ 12| .. |Faintly turbid, |Faint, |0·233 |0·371

| | | light greenish | vegetable| |

| | | yellow | | |

Hudson River, |Dec. 6 | .. |Faintly turbid, |Faint, |0·167 |0·265

at Maple | | | greenish yellow| marshy | |

Island | | | | | |

Hudson River, |Nov. 1 |High |Clear, light |Faint |0·333 |0·530

at inlet | |tide | yellow | | |

| | | | | |

Hudson River, | „ 1 |High |Faintly turbid, |Faint, |0·333 |0·530

at inlet | |tide | light yellow | stale | |

| | | | | |

Hudson River, | „ 1 |Low |Clear, brownish |Faint |0·366 |0·583

at inlet | |tide | yellow | | |

| | | | | |

Hudson River, | „ 1 |Low |Turbid, brownish |Faint |0·366 |0·583

at inlet | |tide | yellow | | |

| | | | | |

Hudson River, |Dec. 4 |High |Slightly turbid, |Oily |0·233 |0·371

50 ft. south | |tide | brownish yellow | | |

of inlet | | | | | |

Hudson River, | „ 4 |Low |Turbid, brownish |Oily |0·183 |0·291

at inlet | |tide | yellow | | |

| | | | | |

Bleecker |Nov. 1 | .. |Clear, faint | .. |0·340 |0·541

Reservoir | | | yellow | | |

| | | | | |

Bleecker | „ 1 | .. |Turbid, faint |Faint, |0·340 |0·541

Reservoir | | | yellow | stale | |

Tivoli Lake | „ 6 | .. |Faint milkiness |Faint, |0·833 |1·325

| | | | stale | |

Tivoli Lake | „ 6 | .. |Whitish, milky |Faint, |0·833 |1·325

| | | | stale | |

Tivoli Lake |Dec. 4 | .. |Turbid, greenish |Faint, |0·966 |1·537

| | | | marshy | |

--------------+-------+-----+-----------------+----------+------+------

--------------+-----------+-----------+----------+---------+----------

|Phosphates.| Nitrites. | | |

| | in | | |

| | Nitrates | | |

| | and | Nitrogen | Free |Albuminoid

| | Nitrites. | Ammonia. |Ammonia. |Ammonia.

--------------+-----------+-----------+----------+---------+----------

Mohawk River, | .. | .. | 0·0705 | 0·0044 | 0·0074

above Diamond|

Woollen Mills|

Hudson River, | .. | .. | 0·0247 | .. | 0·0150

above |

Lansingburg |

Troy hydrant | .. | .. | 0·0284 | 0·0015 | 0·0151

Hudson River, | .. | .. | 0·0614 | 0·0014 | 0·0082

at Maple |

Island |

Hudson River, | .. | .. | 0·0277 | 0·0064 | 0·0002

at inlet |

Hudson River, | .. | .. | 0·0265 | 0·0038 | 0·0142

at inlet |

Hudson River, | .. | .. | 0·0471 | 0·0028 | 0·0134

at inlet |

Hudson River, | .. | .. | 0·0288 | 0·0050 | 0·0124

at inlet |

Hudson River, | .. | .. | 0·0647 | 0·0054 | 0·0114

50 ft. south |

of inlet |

Hudson River, | .. | .. | 0·0606 | 0·0064 | 0·0090

at inlet |

Bleecker | .. | .. | 0·0484 | 0·0052 | 0·0068

Reservoir |

Bleecker | .. | .. | 0·0489 | 0·0046 | 0·0102

Reservoir |

Tivoli Lake |Faint trace|Faint trace| 0·0507 | 0·0184 | 0·0080

Tivoli Lake |Faint trace|Faint trace| 0·0611 | 0·0198 | 0·0280

Tivoli Lake |Faint trace|Faint trace| 0·1334 | 0·0380 | 0·0118

--------------+-----------+-----------+----------+---------+----------

--------------+---------------+-----------------+----------------------

| | Hardness | Mineral Matter.

| | equivalent +--------+ +------

|Oxygen absorbed| to Carbonate | | |Total

| at 80° Fahr. | of lime. |Organic | |Solids

|--------+------+--------+--------+ and | |dried

| In 15 | In 4 | Before | After |Volatile| | at

|Minutes.|hours.|Boiling.|Boiling.|Matter. | |110°.

--------------+--------+------+--------+--------+--------+------+------

Mohawk River, | 0·2071 |0·3704| 6·838 | 6·838 | 1·70 | 9·00 |10·70

above Diamond|

Woollen Mills|

Hudson River, | 0·2691 |0·4150| 3·818 | 3·818 | 2·20 | 5·80 | 8·00

above |

Lansingburg |

Troy hydrant | 0·2750 |0·4000| 4·498 | 4·498 | 2·60 | 6·50 | 9·00

Hudson River, | 0·2827 |0·4100| 5·049 | 4·839 | 2·40 | 5·30 | 7·70

at Maple |

Island |

Hudson River, | 0·1670 |0·3111| 5·897 | 5·897 | 1·40 | 9·80 |11·20

at inlet |

Hudson River, | 0·1890 |0·3422| 6·237 | 6·237 | 5·00 | 7·20 |12·20

at inlet |

Hudson River, | 0·2180 |0·3180| 6·237 | 6·086 | 1·80 | 9·20 |11·00

at inlet |

Hudson River, | 0·2200 |0·3470| 6·048 | 6·048 | 4·80 | 8·20 |13·00

at inlet |

Hudson River, | 0·2509 |0·4340| 5·470 | 5·470 | 3·50 | 4·50 | 8·00

50 ft. south |

of inlet |

Hudson River, | 0·2230 |0·4420| 5·838 | 5·838 | 1·50 | 7·50 | 9·00

at inlet |

Bleecker | 0·1511 |0·2578| 5·330 | 3·893 | 2·50 | 8·80 |11·30

Reservoir |

Bleecker | 0·1755 |0·3020| 6·577 | 6·577 | 5·70 | 6·80 |12·50

Reservoir |

Tivoli Lake | 0·0780 |0·2030| 7·069 | 4·309 | 2·00 |12·00 |14·00

Tivoli Lake | 0·1200 |0·1852| 7·409 | 5·481 | 6·00 |11·00 |17·00

Tivoli Lake | 0·1075 |0·1762| 8·468 | 8·468 | 3·20 |10·40 |13·60

--------------+--------+------+--------+--------+--------+------+------

The variation in the composition of Croton water, at different seasons

of the year, is exhibited by the table on p. 221, which gives the

results of the semi-monthly examinations made by Dr. Elwyn Waller

during the year 1885.[131]

For the results of the analyses of the water of the Hudson River,

recently made by Dr. C. F. Chandler, see table, pp. 222, 223.

The rather common belief that freezing purifies water is incorrect.

It is said, that the greater part of the ice supply of New York City

(three millions of tons) is gathered from the Hudson River between

Albany and Poughkeepsie, most being drawn within thirty miles of the

former city, and therefore liable to be polluted with sewage. The

average number of bacteria in one c.c. of ordinary ice is stated to

approximate 400, but Hudson River ice has been found to contain nearly

2000 bacteria per c.c.[132] The number of bacteria in one c.c. of snow

is usually about 9000; Hudson River snow-ice contains 20,000 per c.c.;

and, although the great majority of these organisms are perfectly

harmless, cases are on record where epidemics (as of gastro-enteritis)

have been directly traced to the use of impure ice.

FOOTNOTES:

[119] This test presupposes the existence in the water of the

substances necessary for the support of vegetable growth.

[120] ‘Water Analysis.’

[121] Jour. Lond. Chem. Soc., xviii. p. 117.

[122] Ibid., xxxv. p. 67.

[123] Sixth Annual Report, Rivers Pollution Commission, “Blue Book.”

[124] Jour. Lond. Chem. Soc. 1867, xx. p. 445.

[125] Phil. Mag., xxx. p. 426.

[126] Ber. der Deutsch. Chem. Gesell. xii. p. 427.

[127] Chem. Soc. Journ., March, 1879.

[128] Pharm. Zeit., 1885, No. 76.

[129] ‘Annual Report of the National Board of Health,’ 1882, p. 207.

[130] Jour. Soc. Chem. Indus., Dec. 1885.

[131] Jour. Am. Chem. Soc., viii. p. 6.

[132] See paper read by Dr. T. M. Prudden before the New York Academy

of Medicine, March 18th, 1887.

VINEGAR.

Vinegar is a dilute aqueous solution of acetic acid, containing

inconsiderable proportions of alcohol, aldehyde, acetic ether, and

extractive matters, which, to some extent, impart a characteristic

flavour and aroma. The process most frequently involved in the

preparation of vinegar is known as the acetous fermentation, and may be

induced in various saccharine juices and infusions, such as those of

apples, wine, malted grain, etc., when, in presence of a ferment, they

are exposed to the action of the air, at a temperature between 24° and

32°. In the oxidation of alcohol, an intermediate compound (aldehyde)

is at first formed, which, by the continued action of oxygen, is

ultimately converted into acetic acid. A dilute solution of alcohol is,

however, not oxidised to acetic acid by simple exposure to the air;

it is usually necessary that a peculiar microscopic plant (_mycoderma

aceti_) should be present. This fungus includes two varieties, viz.,

minute globules (_micrococci_) and rod-like forms (_bacilli_) varying

in size; and is often developed in old casks that have been long

employed for making vinegar. It constitutes a gelatinous mass (“mother

of vinegar”) having the appearance of glue that has been soaked in

cold water; the surface quickly becomes coated with a bluish mould

(_Penicillium glaucum_).

Pasteur regards acetification as a product of the development of the

_mycoderma aceti_, _i.e._, as a physiological fermentation--but it

appears probable that the process is rather one of oxidation, and

that the fungus accelerates the change by condensing the oxygen upon

its surface and delivering it to the alcohol, possibly in the form

of ozone. Indeed, the process of vinegar making may take place in

the entire absence of the _mycoderma_, as when spongy platinum is

brought into contact with alcoholic solutions; and Buchner has examined

shavings which had been used in a vinegar factory for over twenty-five

years, and found them to be absolutely free from the fungoid plant. In

the United States, the best known and most esteemed kind of vinegar

is that obtained by the acetification of apple cider; but by far the

largest quantity is manufactured from alcohol and spirituous liquors.

Cider vinegar is free from aldehyde but contains malic acid. The usual

source of vinegar in Great Britain is a wort prepared from mixtures of

malt with other grain; while, in Continental Europe, inferior sorts

of new wine (especially white wine) are extensively employed for its

production.

Malt vinegar possesses a brown colour and a density ranging from 1·006

to 1·019; that known as proof vinegar contains from 4·6 to 5 per cent.

of acetic acid. In Great Britain the manufacturer is allowed by law

to add 0·1 per cent. of sulphuric acid to vinegar, on account of its

supposed preservative action, and, although the practice is now known

to be unnecessary, it is still sometimes resorted to. The specific

gravity of wine vinegar varies from 1·014 to 1·022. 100 c.c. should

neutralise from 0·6 to 0·7 grains of sodium carbonate, and the solids

obtained upon evaporation to dryness should approximate two per cent.

According to the United States Pharmacopœia, one fluid ounce of vinegar

should require for saturation not less than 35 grains of potassium

bicarbonate.

In 500 samples of imported wine and malt vinegar tested by the author,

the minimum and maximum strength ranged from 3 to 10·6 per cent. of

acetic acid, the specific gravity from 1·0074 to 1·0150, and the number

of grains of potassium bicarbonate required to neutralise one troy

ounce from 22 to 84. Of 273 samples of vinegar tested in 1884 by the

Massachusetts State Board of Health, 52 were above the then legal

standard of 5 per cent. of acetic acid, and 221 below; 109 of the

latter contained more than 4 per cent.; the strongest sample showed

8·86 per cent., and the weakest contained but 0·66 per cent. of acetic

acid. In the year 1885, 114 samples were examined, of which 45 were

above and 69 below the standard of 4½ per cent. acetic acid.

In the State of New York, the legal standard for vinegar is 4·5 of

absolute acetic acid, and, in the case of cider vinegar, the proportion

of total solids must not fall below 2 per cent. In Massachusetts, also,

the acidity must be equivalent to 4½ per cent. of acetic acid, and

cider vinegar must contain, at least, 2 per cent. of solid matter. The

English standard of strength is 3 per cent. of acetic acid.

_Analysis._--For the requirements of the United States Customs Service,

the only estimations ordinarily made are the specific gravity, and a

determination of the acidity. The former is accomplished by means of

the specific gravity bottle; the latter, by placing 10 c.c. of the

sample in a beaker, adding about 30 c.c. of water, then a few drops of

an alcoholic solution of phenol-phthaleïn (to serve as the indicator),

and titrating with a normal alkali-solution; the number of c.c. used

divided by 10 and multiplied by 48, gives the amount, in grains, of

potassium bicarbonate required to neutralise one troy ounce of the

vinegar. In the presence of sulphuric acid, it is necessary to distil

a measured quantity of the sample almost to dryness and titrate the

distillate, it being assumed that 80 per cent. of the total acetic acid

present passes over.

The determination of the extract or solid residue in vinegar is

executed in the same manner as described under beer and wine. Several

tests have been suggested for the detection of the presence of free

sulphuric acid. The usual reagent--barium chloride--is not well adapted

to the direct determination of this acid, since sulphates, which are

as readily precipitated as the free acid, may also be present. The

following methods may be employed:--

1. A piece of cane sugar is moistened with a small quantity of the

sample and exposed to the heat of the water-bath for some time, when,

in presence of free sulphuric acid, the residue will become more or

less carbonised, according to the proportion of acid present.

2. Five centigrammes of pulverised starch are dissolved in a decilitre

of the sample by boiling, and after the liquid has become completely

cooled, a few drops of iodine solution are added. Dilute acetic acid

does not affect starch, and if the sample is pure, a blue coloration

will be produced; if, however, but a minute quantity of sulphuric or

other mineral acid is present, the starch is converted into dextrine,

and the addition of iodine fails to cause the blue coloration.

3. According to Hilger,[133] if two drops of a very dilute solution

of methyl aniline violet (0·1 to 100) are added to about 25 c.c. of

pure vinegar no change of colour takes place; whereas, in the presence