6. The two last operations are repeated._A Dictionary of Arts, Manufactures and Mines containing a clear exposition of their principles and practice

Dingler has endeavoured to separate the colouring matter of the

different sorts of Brazil wood, so as to obtain the same tint from the

coarser as from the best Pernambuco. His process consists in treating

the wood with hot water or steam, in concentrating the decoction so as

to obtain 14 or 15 pounds of it from 4 pounds of wood, allowing it to

cool, and pouring into it two pounds of skim milk; agitating, then

boiling for a few minutes, and filtering. The dun colouring matters are

precipitated by the coagulation of the caseous substance. For dyeing,

the decoctions must be diluted with water; for printing they must be

concentrated, so that 4 pounds of wood shall furnish only 5 or 6 pounds

of decoction, and the liquor may be thickened in the ordinary way. These

decoctions may be employed immediately, as by this treatment they have

acquired the same property as they otherwise could get only by being

long kept. A slight fermentation is said to improve the colour of these

decoctions; some ground wood is put into the decoction to favour this

process.

As gelatine produces no precipitate with these decoctions, they

consequently contain no tannin. Gall-nuts, however, sumach, the bark of

birch or alder, render the colour of Brazil wood more durable, upon

alumed linen and cotton goods, but the shade is a little darker.

In dyeing wool with Pernambuco, the temperature of the bath should never

be above 150° Fahr., since higher heats impair the colour.

According to Dingler and Kurrer, bright and fast scarlet reds may be

obtained upon wool, by preparing a decoction of 50 pounds of Brazil wood

in three successive boils, and setting the decoction aside for 3 or 4

weeks in a cool place; 100 pounds of the wool are then alumed in a bath

of 22 pounds of alum and 11 pounds of tartar, and afterwards rinsed in

cold water. Meanwhile we fill two-thirds with water, a copper containing

30 pails, and heated to the temperature of 150° or 160° F. We pour in 3

pailfuls of the decoction, heat to the same point again, and introduce

30 pounds of wool, which does not take a scarlet, but rather a crimson

tint. This being removed, 2 pails of decoction are put in, and 30 pounds

of wool which becomes scarlet, but not so fine as at the third dip. If

the dyer strengthens the colour a little at the first dip, a little more

at the second, and adds at the third and fourth the quantity of

decoction merely necessary, he will obtain an uniform scarlet tint. With

50 pounds of Pernambuco 1000 pounds of wool may be dyed scarlet in this

way, and with the deposits another 100 may be dyed of a tile colour. An

addition of weld renders the colour faster but less brilliant.

Karkutsch says the dye may be improved by adding some ox-gall to the

bath.

In dyeing cotton the tannin and gallic acid are two necessary mordants,

and the colour is particularly bright and durable, when the cloth has

been prepared with the oily process of Turkey red.

It is said that stale urine heightens the colour of the Brazil dye when

the ground wood is moistened with it.

The quantity of Brazil or Nicaragua wood imported into the United

Kingdom in 1835, was 6,242 tons, whereof 1,811 were exported; of

Brazilietto 230 tons. The duty upon the first article is 5_s._ per ton.

BREAD (_Pain_, Fr.; _Brod_, Germ.) is the spongy mass produced by baking

the leavened or fermented dough of wheat or rye flour, at a proper heat.

It is the principal food of highly civilized nations. The skilful

preparation of this indispensable article constitutes the art of the

Baker. Dough baked without being fermented constitutes cakes or

biscuits; but not bread strictly speaking.

Pliny informs us, that barley was the only species of corn at first used

for food; and even after the method of reducing it to flour had been

discovered, it was long before mankind learned the art of converting it

into cakes.

Ovens were first invented in the East. Their construction was understood

by the Jews, the Greeks, and the Asiatics, among whom baking was

practised as a distinct profession. In this art, the Cappadocians,

Lydians, and Phœnicians, are said to have particularly excelled. It was

not till about 580 years after the foundation of Rome, that these

artisans passed into Europe. The Roman armies, on their return from

Macedonia, brought Grecian bakers with them into Italy. As these bakers

had handmills beside their ovens, they still continued to be called

_pistores_, from the ancient practice of bruising the corn in a mortar;

and their bakehouses were denominated _pistoriæ_. In the time of

Augustus there were no fewer than 329 public bakehouses in Rome; almost

the whole of which were in the hands of Greeks, who long continued the

only persons in that city acquainted with the art of baking good bread.

In nothing, perhaps, is the wise and cautious policy of the Roman

government more remarkably displayed, than in the regulations which it

imposed on the bakers within the city. To the foreign bakers who came to

Rome with the army from Macedonia, a number of freedmen were associated,

forming together an incorporation from which neither they nor their

children could separate, and of which even those who married the

daughters of bakers were obliged to become members. To this

incorporation were entrusted all the mills, utensils, slaves, animals,

every thing, in short, which belonged to the former bakehouses. In

addition to these, they received considerable portions of land; and

nothing was withheld, which could assist them in pursuing, to the best

advantage, their highly prized labours and trade. The practice of

condemning criminals and slaves, for petty offences, to work in the

bakehouse, was still continued; and even the judges of Africa were bound

to send thither, every five years, such persons as had incurred that

kind of chastisement. The bakehouses were distributed throughout the

fourteen divisions of the city, and no baker could pass from one into

another without special permission. The public granaries were committed

to their care; they paid nothing for the corn employed in baking bread

that was to be given in largess to the citizens; and the price of the

rest was regulated by the magistrates. No corn was given out of these

granaries except for the bakehouses, and for the private use of the

prince. The bakers had besides private granaries, in which they

deposited the grain, which they had taken from the public granaries for

immediate use; and if any of them happened to be convicted of having

diverted any portion of the grain to another purpose, he was condemned

to a ruinous fine of five hundred pounds weight of gold.

Most of these regulations were soon introduced among the Gauls; but it

was long before they found their way into the more northern countries of

Europe. Borrichius informs us that in Sweden and Norway, the only bread

known, so late as the middle of the 16th century, was unleavened cakes

kneaded by the women. At what period in our own history the art of

baking became a separate profession, we have not been able to ascertain;

but this profession is now common to all the countries in Europe, and

the process of baking is also nearly the same.

The French, who particularly excel in the art of baking, have a great

many different kinds of bread. Their _pain bis_, or brown bread, is the

coarsest kind of all, and is made of coarse groats mixed with a portion

of white flour. The _pain bis blanc_, is a kind of bread between white

and brown, made of white flour and fine groats. The _pain blanc_, or

white bread, is made of white flour, shaken through a sieve after the

finest flour has been separated. The _pain mollet_, or soft bread, is

made of the purest flour without any admixture. The _pain chaland_, or

customers’ bread, is a very white kind of bread, made of pounded paste.

_Pain chapelé_, is a small kind of bread, with a well-beaten and very

light paste, seasoned with butter or milk. This name is also given to a

small bread, from which the thickest crust has been removed by a knife.

_Pain cornu_, is a name given by the French bakers to a kind of bread

made with four corners, and sometimes more. Of all the kinds of small

bread, this has the strongest and firmest paste. _Pain à la reine_,

queen’s bread, _pain à la Sigovie_, _pain chapelé_, and _pain cornu_,

are all small kinds of bread, differing only in the lightness or

thickness of the paste. _Pain gruau_ is a small very white bread made

now in Paris, from the flour separated after a slight grinding from the

best wheat. Such flour is in hard granular particles.

In this country we have fewer varieties of bread, and these differ

chiefly in their degrees of purity. Our white or fine bread is made of

the purest flour; our wheaten bread, of flour with a mixture of the

finest bran; and our household bread, of the whole substance of the

grain without the separation either of the fine flour or coarse bran. We

have also symnel bread, manchet or roll bread, and French bread, which

are all made of the purest flour from the finest wheat; the roll bread

being improved by the addition of milk, and the French bread by the

addition of eggs and butter. To these may be added gingerbread, a cake

made of flour, with almonds, liquorice, aniseed, rose-water, and sugar

or treacle; and mastlin bread, made of wheat and rye, or sometimes of

wheat and barley. We have various kinds of small bread, having various

names, according to their various forms. They are, in general, extremely

light, and are sweetened with sugar, currants, and other palatable

ingredients. In Scotland there is a cake called _short bread_, made from

a pretty thick dough, enriched with butter, sweetened with sugar, and

seasoned with orange peel, or other kinds of spices.

The process of making bread is nearly the same in all the countries of

modern Europe; though the materials of which it as composed vary with

the farinaceous productions of different climates and soils. The flour

of wheat is most generally employed for this purpose, wherever that

vegetable can be reared. This flour is composed of a small portion of

mucilaginous saccharine matter, soluble in cold water, from which it may

be separated by evaporation; of a great quantity of starch, which is

scarcely soluble in cold water, but capable of combining with that fluid

by means of heat; and an adhesive gray substance called gluten,

insoluble in water, ardent spirit, oil, or ether, and resembling an

animal substance in many of its properties. Flour kneaded with water,

forms a tough rather indigestible paste containing all the constituent

parts which we have enumerated. Heat produces a considerable change on

the glutinous part of this compound, and renders it more easy of

mastication and digestion. Still, however, it continues heavy and tough,

compared with bread which is raised by leaven or yeast. Leaven is

nothing more than a piece of dough, kept in a warm place till it

undergoes a process of fermentation; swelling, becoming spongy, or full

of air bubbles, at length disengaging an acidulo-spirituous vapour, and

contracting a sour taste. When this leaven is mingled in proper

proportions with fresh-made dough, it makes it rise more readily and

effectually than it would do alone, and gives it at the same time a

greater degree of firmness. Upon the quality of the leaven employed, the

quality of the bread materially depends.

The principal improvement which has been made on bread in modern times,

is the substitution of yeast or barm in place of common leaven. This

yeast is the viscid froth that rises to the surface of beer, in the

first stage of its fermentation. When mixed with the dough, it makes it

rise much more speedily and effectually than ordinary leaven, and the

bread is of course much lighter, and freer from that sour and

disagreeable taste which may often be perceived in bread raised with

leaven, either because too much is mingled with the paste, or because it

has been allowed to advance too far in the process of fermentation.

Bread properly raised and baked, differs materially from unleavened

cakes, not only in being less compact and heavy, and more agreeable to

the taste, but in losing its tenacious and glutinous qualities, and thus

becoming more salutary and digestible.

We possess several analyses of wheat flour. Ordinary wheat (_triticum

hybernum mixed with triticum turgidum_) contains, according to the

analyses made by Vauquelin of several species of wheat flour, the

following substances:--

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

| | | | | |

| | | | | |

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

|French wheat flour | 10·0 | 10·96 | 71·49 | 4·72 |

|Hard wheat of Odessa flour| 12·0 | 14·55 | 56·50 | 8·48 |

|Soft wheat of Odessa flour| 10·0 | 12·00 | 62·00 | 7·56 |

|Same sort of flour | 8·0 | 12·10 | 70·84 | 4·90 |

|Same sort of flour | 12·0 | 7·30 | 72·00 | 5·42 |

|Wheat of the French bakers| 10·0 | 10·20 | 72·80 | 4·20 |

|Flour of the Paris hos- | 8·0 | 10·30 | 71·20 | 4·80 |

|Ditto (3d quality) | 12·0 | 9·02 | 67·78 | 4·80 |

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

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

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

|French wheat flour | 3·32 | - |100·49| 50·3 |

|Hard wheat of Odessa flour| 4·90 | 2·3 | 98·73| 51·2 |

|Soft wheat of Odessa flour| 5·80 | 1·2 | 98·42| 54·8 |

|Same sort of flour | 4·60 | - |100·41| 37·4 |

|Same sort of flour | 3·30 | - |100·02| 37·2 |

|Wheat of the French bakers| 2·80 | - |100·00| 40·6 |

|Flour of the Paris hos- | 3·60 | - | 97·90| 37·8 |

|Ditto (3d quality) | 4·60 | 2·0 |100·21| 37·8 |

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

The following table of analyses merits also a place here.

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

| | | | | |gluten.|men. | |

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

|Flour of the | 1 | 22· | 74· | 5·50| 1· | 1·50| |

|Ditto triticum | 1 | 24· | 68· | 5·0 | 1· | 1·50| |

|Ditto common wheat| - | 12·5 | 74·5 | 12· | 2· | | |

|Ditto wheat and | 6 | 9·80 | 75·50 | 4·22| 3·28 | - | 1·2 |

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

The first two of the above analyses were made by Vogel, the third by

Proust, and the fourth by Vauquelin.

Analyses of the flour of some other corns.

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

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

|White | 59·00 | 2·5 | - |4·30 | 8·25 | 2 | |

|Barley | 32·00 | 9· | 3· | - | 2 | - | 55 |

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

The first analysis is by Vogel, the second by Proust.

It deserves to be remarked, that the flour of Odessa contains a much

greater quantity of sugar than the French flour. The substance indicated

in the preceding table by the name of gluten, is the gluten of Beccaria,

that is to say, a mixture of gluten and vegetable albumen. The gum of

wheat is not quite identical with ordinary gum. It is a brown azotised

substance, which, when treated by nitric acid, affords no mucic acid,

but oxalic acid and the bitter principle of Welter. It contains besides

superphosphate of lime.

The last column of the first table exhibits the quantity of water

necessary to convert the flour into dough of the ordinary consistence,

and it is usually proportional to the quantity of gluten. The hard wheat

of Odessa forms an exception in this respect; the reason of the

difference being that the starch contained in this flour is not as in

ordinary flour in a fine powder, but in small transparent grains, which

resemble pounded gum, and absorb less water than pulverulent starch.

The _triticum monococcon_, according to Zenneck, contains in its

unsifted flour, 16·334 of gluten and vegetable albumen; 64·838 of

starch; 11·347 of gum, sugar, and extractive; 7·481 of husks. The sifted

flour affords 15·536 of gluten and vegetable albumen; 76·459 of starch;

7·198 of sugar, gum, and extractive; 0·807 of husky matter. It is

difficult to conceive how such great quantities of gluten, albumen, and

extractive matter, could disappear in the sifting. The triticum spelta

contains in 100 parts of the finest flour, 22·5 of a soft and humid

gluten, mixed with vegetable albumen; 74 of starch, and 5·5 of sugar.

Here we have an excess of 2 parts in the 100.

Wheat furnishes very little ashes by incineration, not more than 0·15

per cent. of the weight; containing superphosphates of soda, lime, and

magnesia.

The object of baking is to combine the gluten and starch of the flour

into a homogeneous substance, and to excite such a vinous fermentative

action, by means of its saccharine matter, as shall disengage abundance

of carbonic acid gas in it for making an agreeable, soft, succulent,

spongy, and easily digestible bread. The two evils to be avoided in

baking are, hardness on the one hand, and pastiness on the other.

Well-made bread is a chemical compound, in which the gluten and starch

cannot be recognized or separated, as before, by a stream of water. When

flour is kneaded into a dough, and spread into a cake, this cake, when

baked, will be horny if it be thin, or if thick, will be tough and

clammy; whence we see the value of that fermentative process, which

generates thousands of little cells in the mass or crumb, each of them

dry, yet tender and succulent, through the intimate combination of the

moisture. By this constitution it becomes easily soluble in the juices

of the stomach, or in other words, light of digestion. It is moreover

much less liable to turn sour than cakes made from unfermented dough.

Rye, which also forms a true spongy bread, though inferior to that of

wheat, consists of similar ingredients; namely, 61·07 of starch; 9·48 of

gluten; 3·28 of vegetable albumen; 3·28 of uncrystallizable sugar; 11·09

of gum; 6·38 of vegetable fibre; the loss upon the 100 parts amounted to

5·62, including an acid whose nature the analyst, M. Einhof, did not

determine. Rye flour contains also several salts, principally the

phosphates of lime and magnesia. This kind of grain forms a

dark-coloured bread reckoned very wholesome; comparatively little used

in this country, but very much in France, Germany, and Belgium.

Dough fermented with the aid either of leaven or yeast, contains little

or none of the saccharine matter of the flour, but in its stead a

certain portion, nearly half its weight, of spirit, which imparts to it

a vinous smell, and is volatilized in the oven; whence it might be

condensed into a crude weak alcohol, on the plan of Mr. Hick’s patent,

were it worth while. But the increased complexity of the baking

apparatus, will probably prove an effectual obstacle to the commercial

success of this project, upon which already upwards of 20,000_l._

sterling have been squandered.

That the sugar of the flour is the true element of the fermentation

preposterously called panary, which dough undergoes, and that the starch

and gluten have nothing to do with it, may be proved by decisive

experiments. The vinous fermentation continues till the whole sugar is

decomposed, and no longer; when if the process be not checked by the

heat of baking, the acetous fermentation will supervene. Therefore if a

little sugar be added to a flour which contains little or none, its

dough will become susceptible of fermenting, with extrication of gas, so

as to make spongy succulent bread. But since this sponginess is produced

solely by the extrication of gas, and its expansion in the heat of the

oven, any substance capable of emitting gas, or of being converted into

it under these circumstances, will answer the same purpose. Were a

solution of bicarbonate of ammonia obtained by exposing the common

sesqui-carbonate in powder for a day to the air, incorporated with the

dough, in the subsequent firing it will be converted into vapour, and in

its extrication render the bread very porous. Nay, if water highly

impregnated with carbonic acid gas be used for kneading the dough, the

resulting bread will be somewhat spongy. Could a light article of food

be prepared in this way, then as the sugar would remain undecomposed,

the bread would be so much the sweeter, and the more nourishing. How far

a change propitious to digestion takes place in the constitution of the

starch and gluten, during the fermentative action of the dough, has not

been hitherto ascertained by precise experiments. Medical practitioners,

who derive an enormous revenue from dyspepsia, should take some pains

to investigate this subject.

Dr. Colquhoun, in his able essay upon the art of making bread, has shown

that its texture when prepared by a sudden formation and disengagement

of elastic fluid generated within the oven, differs remarkably from that

of a loaf which has been made after the preparatory fermentation with

yeast. Bread which has been raised with the common carbonate of ammonia

as used by the pastry-cooks, is porous no doubt, but not spongy with

vesicular spaces, like that made in the ordinary way. The former kind of

bread never presents that air-cell stratification which is the boast of

the Parisian baker, but which is almost unknown in London. I have found

it moreover very difficult to expel by the oven the last portion of the

ammonia, which gives both a tinge and a taste to the bread. I believe,

however, that the bicarbonate would be nearly free from this objection,

which operates so much against the sesqui-carbonate of the shops.

In opposition to Mr. Edlin’s account of the excellent quality of bread

made by impregnating dough with carbonic acid gas[10], Dr. Colquhoun

adduces Vogel’s experiments, which show that such dough, when baked,

after having been kept in a warm situation during the usual time,

afforded nothing better than a hard cake, which had no resemblance to

common bread. Vogel further states, as illustrative of the general

necessity of providing a sufficient supply of disengaged elastic fluid

within the dough, before baking it at all, that when he made various

attempts to form a well-raised vesicular loaf, within the oven, by

mixing flour with carbonate of magnesia, or with zinc filings, and then

kneading it into a paste by means of water, acidulated with sulphuric

acid, he always met with complete failure and disappointment. Dr.

Colquhoun performed a series of well-devised experiments on this

subject, which fully confirmed Vogel’s results, and prove that a proper

spongy bread cannot be made by the agency of either carbonic acid water,

or of mixtures of sesqui-carbonate of soda, and tartaric acid. The bread

proved doughy and dense in every case, though less so with the latter

mixture than the former. No loaf bread can, indeed, be well made by any

of these two extemporaneous systems, because they are inconsistent with

the thorough kneading of the dough. It is this process which renders

dough at once elastic enough to expand when carbonic acid gas is

generated within it, and cohesive enough to confine the gas when it is

generated. The whole gas of the loaf is disengaged in its interior by a

continuous fermentation, after all the processes of kneading have been

finished; for the loaf, after being kneaded, weighed out, and shaped, is

set aside till it expands gradually to double its bulk, before it is put

into the oven. But when a dough containing sesqui-carbonate of soda is

mixed with one containing muriatic acid, in due proportions to form the

just dose of culinary salt, the gas escapes during the necessary

incorporation of the two, and the bread formed from it is dense and

hard. Dr. Whiting has, however, made this old chemical process the

subject of a new patent for baking bread.

[10] Treatise on the Art of Bread Making, p. 56.

When the baker prepares his dough, he takes a portion of the water

needed for the batch, having raised its temperature to from 70° to 100°

F., dissolves a certain proportion of his salt in it, then adds the

yeast, and a certain quantity of his flour. This mixture, called the

_sponge_, is next covered up in the small kneading-trough, alongside of

the large one, and let alone for _setting_ in a warm situation. In about

an hour, signs of vinous fermentation appear, by the swelling and

heaving up of the sponge, in consequence of the generation of carbonic

acid; and if it be of a semi-liquid consistence, large air bubbles will

force their way to the surface, break, and disappear in rapid

succession. But when the _sponge_ has the consistence of thin _dough_,

it confines the gas, becomes thereby equably and progressively inflated

to double its original volume; when no longer capable of containing the

pent-up air, it bursts and subsides. This process of rising and falling

alternately might be carried on during twenty-four hours, but the baker

has learned by experience to guard against allowing full scope to the

fermentative principle. He generally interferes after the first, or at

furthest after the second or third dropping of the sponge; for were he

not to do so, the bread formed with such dough would invariably be found

sour to the taste and the smell. Therefore he adds at this stage to the

sponge the reserved proportions of flour, salt, and water, which are

requisite to make the dough of the desired consistence and size; and

next incorporates the whole together by a long and laborious course of

kneading. When this operation has been continued till the fermenting and

the fresh dough have been intimately blended, and till the glutinous

matter of both is worked into such union and consistence that the mass

becomes so tough and elastic as to receive the smart pressure of the

hand without adhering to it, the kneading is suspended for some time.

The dough is now abandoned to itself for a few hours, during which it

continues in a state of active fermentation throughout its entire mass.

Then it is subjected to a second but much less laborious kneading, in

order to distribute the generated gas as evenly as possible among its

parts, so that they may all partake equally of the vesicular structure.

After this second kneading, the dough is weighed out into the portions

suitable to the size of bread desired; which are of course shaped into

the proper forms, and once more set aside in a warm situation. The

continuance of the fermentation soon disengages a fresh quantity of

carbonic acid gas, and expands the lumps to about double their pristine

volume. These are now ready for the oven, and when they finally quit it

in the baked state, are about twice the size they were when they went

in. The generation of the due quantity of gas should be complete before

the lumps are transferred to the oven; because whenever they encounter

its heat, the process of fermentation is arrested; for it is only the

previously existing air which gets expanded throughout every part of the

loaf, swells out its volume, and gives it the _piled_ and vesicular

texture. Thus the well-baked loaf is composed of an infinite number of

cellules filled with carbonic acid gas, and apparently lined with a

glutinous membrane of a silky softness. It is this which gives the

light, elastic porous constitution to bread.

After suffering the fermentative process to exhaust itself in a mass of

dough, and the dough to be brought into that state in which the addition

of neither yeast, nor starch, nor gluten will produce any effect in

restoring that action, if we mix in 4 per cent. of saccharine matter, of

any kind, with a little yeast, the process of fermentation will

immediately re-commence, and pursue a course as active and lengthened as

at first, and cease about the same period.[11]

[11] Dr. Colquhoun, in Annals of Philosophy for 1826, vol. xii. p.

171.

This experiment, taken in connection with the facts formerly stated,

proves that what was called panary fermentation, is nothing but the

ancient and well-known process of the vinous fermentation of sugar,

which generates alcohol. There seems to be but one objection to the

adoption of this theory. After the loaf is baked, there is found in its

composition nearly as much saccharine matter as existed in the flour

before fermentation. M. Vogel states that in the baked bread there

remains 3·6 parts of sugar, out of the 5 parts which it originally

contained. Thus, in 100 parts of loaf bread prepared with wheaten flour,

distilled water, and yeast without the admixture of any common salt, he

found the following ingredients:--

Sugar 8·6

Torrefied or gummy starch 18·0

Starch 53·5

Gluten, combined with a little starch, 20·75

Exclusive of carbonic acid, muriate of lime, phosphate of lime, &c.

It must be borne in mind that in every loaf the process of fermentation

has been prematurely checked by the baker’s oven, and therefore the

saccharine constituent can never be wholly decomposed. It seems certain,

also, that by the action of gluten upon the starch in the early stage of

the firing, a quantity of sugar will be formed by the saccharine

fermentation; which we have explained in treating of BEER.

Several masses of dough were prepared by Dr. Colquhoun in which pure

wheat starch was mixed with common flour, in various proportions. In

some of the lumps this starch had been gelatinized, with the _minimum_

of hot water, before it was added to the flour. After introducing the

usual dose of salt, the dough was thoroughly kneaded, set apart for the

proper period, allowed to ferment in the accustomed way, and then baked

in the oven. In outward appearance, increase of bulk, and vesicular

texture, none of them differed materially from a common loaf, baked

along with them for the sake of comparison; except that when the starch

considerably exceeded the proportion of flour in the lump, the loaf,

though whiter, had not risen so well, being somewhat less vesicular.

But, on tasting the bread of each loaf, those which contained most

gelatinized starch were unexpectedly found to be the sweetest. The other

loaves, into which smaller quantities of the gelatinized starch had been

introduced, or only some dry starch, had no sweetish taste whatever to

distinguish them from ordinary bread. These facts seem to establish the

conclusion, that the presence of gelatinous starch in bread put into the

oven, is a means of forming a certain portion of saccharine matter

within the loaf, during the baking process. Now it is more than probable

that gelatinized starch does exist, more or less, in all loaves which

have been fermented by our usual methods, and hence a certain quantity

of sugar will necessarily be generated at its expense, by the action of

heat. Thus the difficulty started by M. Vogel is sufficiently solved;

and there remains no doubt that, in the saccharine principle of flour,

the fermentation has its origin and end, while dough is under

fermentation.

The source of the sourness which supervenes in bread, under careless or

unskilful hands, had been formerly ascribed to each of all the

constituents of flour; to its gluten, its starch, and its sugar; but

erroneously, as we now see: for it is merely the result of the second

fermentation which always succeeds the vinous, when pushed improperly

too far. It has been universally taken for granted by authors, that the

acid thus generated in dough is the acetic. But there appear good

grounds to believe that it is frequently a less volatile acid, probably

the lactic, particularly when the process has been tardy, from the

imperfection of the yeast or the bad quality of the flour. The

experiments of Vogel, Braconnot, and others, prove that the latter acid

is generated very readily, and in considerable quantity during the

spontaneous decomposition of a great many vegetable substances, when in

a state of humidity. The presence of lactic acid would account for the

curious fact, that the acidity of unbaked dough is much more perceptible

to the taste than to the smell; while the sourness of the same piece of

bread, after coming out of the oven, is, on the contrary, much more

obvious to the olfactory organs than to the palate. But this is exactly

what ought to happen, if the lactic acid contributes, in conjunction

with the acetic, to produce the acescence of the dough. At the ordinary

temperature of a bakehouse, the former acid, though very perceptible in

the mouth, is not distinguishable by the nostrils; but as it is easily

decomposed by heat, no sooner is it exposed to the high temperature of

the oven, than it is resolved, in a great measure, into acetic acid[12],

and thus becomes more manifest to the sense of smell, and less to that

of taste. This theory seems to explain satisfactorily all the phenomena

accompanying the progress of fermentation in baker’s dough, and also

some of its results in the process of baking which do not easily admit

of any other solution.

[12] Berzelius.

There are extremely simple and effectual methods for enabling the baker

to adopt measures either to prevent or correct the evil of acescence,

and these are to neutralize the acid by the due exhibition of an alkali,

such as soda; or an alkaline earth, such as magnesia or chalk. And it

affords a striking proof of how much the artisan has been accustomed to

plod, uninquiring and uninformed, over the same ground, that a remedy so

safe and so economical, should remain at this day unthought of and

unemployed by most of the manufacturers of bread in the United Kingdom.

The introduction of a small portion of carbonate of soda will rectify

any occasional error in the result of the so called panary fermentation,

and will, in fact, restore the dough to its pristine sweetness. The

quantity of acetate of soda, which will be thus present in the bread,

will be altogether inconsiderable; and as it has no disagreeable taste,

and is merely aperient to the bowels in a very mild degree, it can form

no objection in the eye of the public police. The restoration of dough

thus tainted with acid, and its conversion into pleasant and wholesome

bread, has been sufficiently verified by experiment. But, according to

Mr. Edmund Davy, carbonate of magnesia may be used with still greater

advantage, as during the slow action of the acid upon it, the carbonic

acid evolved serves to open up and lighten bread which would otherwise

be dense and doughy from the indifferent quality of the flour. Here,

however, the dangerous temptation lies with a sordid baker to use cheap

or damaged flour, and to rectify the bread made of it by chemical

agents, innocent in themselves, but injurious as masks of a bad raw

material. When sour yeast must be used, as sometimes happens with the

country bakers, or in private houses at a distance from beer breweries,

there can be no harm, but, on the contrary, much propriety, in

correcting its acidity, by the addition of as much carbonate of soda to

it as will effect its neutralization, but nothing more. When sour yeast

has been thus corrected, it has been found, in practice, to possess its

fermentative power unimpaired, and to be equally efficacious, with fresh

formed yeast, in making good palatable loaves.

We have seen that, in baking, about one fourth of the starch is

converted into a matter possessing the properties of _British gum_ (see

STARCH), and also that the gluten, though not decomposed, has its

particles disunited, and is not so tough and adhesive as it is in the

flour. This principle is also, as we have said, useful in cementing all

the particles of the dough into a tenacious mass, capable of confining

the elastic fluid generated by the vinous fermentation of the sugar.

Starch is the main constituent, the basis of nourishment in bread, as

well as in all farinaceous articles of food. The albumen also of the

wheat being coagulated by the heat of the oven, contributes to the

setting of the bread into a consistent elastic body.

In the mills in the neighbourhood of London, no less than seven distinct

sorts of flour are ground out of one quantity of wheat. These are for

one quarter--

Fine flour 5 bushels 3 pecks.

Seconds 0 2

Fine middlings 0 1

Coarse middlings 0 0·5

Bran 3 0

Twenty-penny 3 0

Pollard 2

--- ---

14 2·5

So that we have nearly a double bulk of flour, or 14 bushels and 2-1/2

pecks from 8 bushels of wheat. In the sifting of the flour through the

bolter, there is a fine white angular meal obtained called sharps, which

forms the central part of the grain. It is consumed partly by the fine

biscuit bakers. The bakers of this country were formerly bound by law to

bake three kinds of bread, the _wheaten_, _standard wheaten_, and the

_household_; marked respectively with a W, S W, and H, and if they

omitted to make these marks on their bread they were liable to a

penalty. The size of the loaves were usually peck, half-peck, quartern,

and half-quartern; the weights of which, within 48 hours of their being

baked, should have been respectively 17 lbs. 6 oz.; 8 lbs. 11 oz.; 4

lbs. 5 oz. 8 dr.; and 4 lbs. 2 oz. 14 dr. In general they weigh about

one-seventh more before they enter the oven, or they lose one-seventh of

their weight in baking. The French bread loses fully one-sixth in the

oven, owing chiefly to its more oblong thin shape, as compared to the

cubical shape of the English bread. But this loss of weight is very

variable, being dependent upon the quality of the wheaten flour, and the

circumstances of baking. The present law in England defines the quartern

loaf at 4 lbs., and subjects the baker to a penalty if the bread be one

ounce lighter than the standard. Hence it leaves the baker in

self-defence, to leave it in rather a damp and doughy state. But there

is much light bread sold in London. I have met with quartern loaves of 3

lbs. 10 ozs. A sack of flour weighing 280 lbs. was presumed by the

framers of our former parliamentary acts, for the assize of bread, to be

capable of being baked into 80 loaves. If this proportion had been

correct, one-fifth part of our quartern loaf must consist of water and

salt, and four-fifths of flour. But in general, of good wheaten flour,

three parts will take up one part of water; so that the sack of flour

should have turned out, and actually did turn out, more than 80 loaves.

At present with 4 lb. bread it may well yield 92 loaves.

The following statement of the system of baking at Paris, I received in

1835 from a very competent judge of the business.

1,000 kilogrammes of wheat = 5 quarters English, cost 200 fr., and yield

800 kilos of flour of the best white quality, equivalent to 5-1/10 sacks

French. Hence the sack of flour costs 40 francs at the mill, and

including the carriage to Paris, it costs 45 or 46 francs.

The profit of the flour dealer is about 3-1/2 francs, and the sale price

becomes from 43 to 50 francs.

_Bread manufactured from the above._

_£_ _s._ _d._ _£_ _s._ _d._

One day’s work of an ordinary baker, 6 0 0

who makes fourbatches in a day,

consists of 3 sacks at 50 francs, or

2_l._ sterling each

Salt 2-3/4 lbs. at 2_d._ per lb. 0 0 5-1/2

Yeast or leaven 3 lbs. at 5_d._ 0 1 3

---------------

Total cost of materials 6 1 8-1/2

_Expenses of Baking._

Three workmen at different rates of 0 12 0

wages, 15 francs

Fire-wood 0, as the charcoal pro-

duced pays for it

General expenses, such as rent, 0 12 0

taxes, interest of capital, &c.

----------

1 4 0 = 1 4 0

--------------

7 5 8-1/2

For this sum 315 loaves are made, 7 17 6

being 105 for every sack of flour

weighing 156·66 kilos, or 344-2/3

lbs. avoird. One loaf contains

therefore 344·65/105 = 3·282 lbs.,

and as 100 lbs. of flour in Parisian

baking are reckoned to produce 127

lbs. of bread, each loaf will weigh

4·168 lbs., avoird., and will cost

7_l._ 5_s._ 8-1/2_d._ divided by 315

= 5-1/2_d._ very nearly. The value

of 315 loaves at the sale price of

6_d._ will be

--------------

Upon this day’s work the clear 0 11 9-1/2

profit is therefore

A new baking establishment has been recently formed at the Royal

Clarence Victualling Establishment at Weevil, near Portsmouth, upon a

scale of magnitude nearly sufficient to supply the whole royal navy with

biscuits, and that of a very superior description. The following account

of it is taken from the United Service Journal. “It having been

discovered that the flour supplied to government by contract, had in

many instances been most shamefully adulterated, the corn is ground at

mills comprised within the establishment, by which means the

introduction of improper ingredients is prevented, and precisely the

proportion of bran which is requisite in the composition of good

sea-biscuit is retained, and no more. The flour-mill is furnished with

10 pairs of stones, by which 40 bushels of flour may be ground and

dressed ready for baking, in an hour. The baking establishment consists

of 9 ovens, each 13 feet long by 11 feet wide, and 17-1/2 inches in

height. These are each heated by separate furnaces, so constructed that

a blast of hot air and fire sweeps through them, and gives to the

interior the requisite dose of heat in an incredible short space of

time. The first operation in making the biscuits, consists in mixing the

flour or rather meal and water; 13 gallons of water are first introduced

into a trough, and then a sack of the meal, weighing 280 lbs. When the

whole has been poured in by a channel communicating with an upper room,

a bell rings, and the trough is closed. An apparatus consisting of two

sets of what are called knives, each set ten in number, are then made to

revolve amongst the flour and water by means of machinery. This mixing

operation lasts one minute and a half, during which time the double

set of knives or stirrers makes twenty-six revolutions. The next

process is to cast the lumps of dough under what are called the

breaking-rollers,--huge cylinders of iron, weighing 14 cwt. each, and

moved horizontally by the machinery along stout tables. The dough is

thus formed into large rude masses 6 feet long by 3 feet broad, and

several inches thick. At this stage of the business, the kneading is

still very imperfect, and traces of dry flour may still be detected.

These great masses of dough are now drawn out, and cut into a number of

smaller masses about a foot and a half long by a foot wide, and again

thrust under the rollers, which is repeated until the mixture is so

complete that not the slightest trace of any inequality is discoverable

in any part of the mass. It should have been stated that two workmen

stand one at each side of the rollers, and as the dough is flattened

out, they fold it up, or double one part upon another, so that the

roller at its next passage squeezes these parts together, and forces

them to mix. The dough is next cut into small portions, and being placed

upon large flat boards, is, by the agency of machinery, conveyed from

the centre to the extremity of the baking-room. Here it is received by a

workman, who places it under what is called the sheet roller, but which,

for size, colour, and thickness, more nearly resembles a blanket. The

kneading is thus complete, and the dough only requires to be cut into

biscuits before it is committed to the oven. The cutting is effected by

what is called the cutting-plate, consisting of a net-work of 52

sharp-edged hexagonal frames, each as large as a biscuit. This frame is

moved slowly up and down by machinery, and the workman, watching his

opportunity, slides under it the above-described blanket of dough, which

is about the size of a leaf of a dining table; and the cutting-frame in

its descent indents the sheet, but does not actually cut it through, but

leaves sufficient substance to enable the workman at the mouth of the

oven to jerk the whole mass of biscuits unbroken into it. The dough is

prevented sticking to the cutting-frame by the following ingenious

device: between each of the cutter-frames is a small flat open frame,

movable up and down, and loaded with an iron ball, weighing several

ounces. When the great frame comes down upon the dough, and cuts out 52

biscuits, each of these minor frames yields to the pressure, and is

raised up; but as soon as the great frame rises, the weight of the balls

acting upon the little frames, thrusts the whole blanket off, and allows

the workmen to pull it out. One quarter of an hour is sufficient to bake

the biscuit, which is afterwards placed for three days in a drying room,

heated to 85° or 90°, which completes the process.” The following

statement of the performance of the machinery is taken from actual

experiment; in 116 days, during 68 of which, the work was continued for

only 7-1/2 hours; and during 48, for only 5-3/4 hours each day, in all

769 working hours, equal to 77 days of 10 hours each; the following

quantity of biscuit was baked in the 9 ovens; viz., 12,307 cwt. =

1,378,400 lbs. The wages of the men employed in baking this quantity

amounted to 273_l._ 10_s._ 9-1/2_d._; if it had been made by hand, the

wages would have been 933_l._ 9_s._ 10_d._; saving in the wages of

labour, 659_l._ 7_s._ 0-1/2_d._ In this, is not included any part of the

interest of the sum laid out upon the machine, or expended in keeping it

in order. But in a very few years at such an immense rate of saving, the

cost of the engine and other machinery will be repaid. This admirable

apparatus is the invention of T. T. Grant, Esq. storekeeper of the Royal

Clarence Victualling Establishment, who, we believe, has been properly

rewarded, by a grant of 2,000_l._ from government.

The labour of incorporating the ingredients of bread, viz. flour, water

and salt, or kneading dough, is so great as to have led to the

contrivance of various mechanical modes of producing the same effect.

One of the most ingenious is that for which a patent was obtained in

August, 1830, by Mr. Edwin Clayton. It consists of a rotatory kneading

trough, or rather barrel, mounted in bearings with a hollow axle, and of

an interior frame of cast iron made to revolve by a solid axle which

passes through the hollow one; in the frame there are cutters diagonally

placed for kneading the dough. The revolving frame and its barrel are

made to turn in contrary directions, so as greatly to save time and

equalize the operation. This double action represents kneading by the

two hands, in which the dough is inverted from time to time, torn

asunder, and reunited in every different form. The mechanism will be

readily understood from the following description.

[Illustration: 169]

_Fig._ 169. exhibits a front elevation of a rotatory kneading trough,

constructed according to improvements specified by the patentee, the

barrel being shown in section: _a_ is the barrel, into which the several

ingredients, consisting of flour, water, and yeast, are put, which

barrel is mounted in the frame-work _b_, with hollow axles _c_ and _d_,

which hollow axles turn in suitable bearings at _e_; _f_ is the

revolving frame which is mounted in the interior of the barrel _a_, by

axles _g_ and _h_. The ends of this revolving frame are fastened, or

braced together by means of the oblique cutters or braces _i_, which act

upon the dough when the machine is put in motion, and thus cause the

operation of kneading.

Either the barrel may be made to revolve without the rotatory frame, or

the rotatory frame without the barrel, or both may be made to revolve

together, but in opposite ways. These several motions may be obtained by

means of the geer-work, shown at _k_, _l_, and _m_, as will be presently

described.

If it be desired to have the revolving motion of the barrel and rotatory

frame together, but in contrary directions, that motion may be obtained

by fastening the hollow axle of the wheel _m_, by means of a screw _n_,

to the axle _h_, of the rotatory frame _f_, tight, so as they will

revolve together, the other wheels _k_ and _l_ being used for the

purpose of reversing the motion of the barrel. It will then be found

that by turning the handle _o_, the two motions will be obtained.

If it be desired to put the rotatory frame _f_, only into motion, that

action will be obtained by loosening the screw _n_, upon the axle of the

wheel _m_, when it will be found that the axle _h_, will be made to

revolve freely by means of the winch _o_, without giving motion to the

wheels _k_, _l_, and _m_, and thus the barrel will remain stationary. If

the rotatory action of the barrel be wanted, it will be obtained by

turning the handle _p_, at the reverse end of the machine, which,

although it puts the geer at the opposite end of the barrel into motion,

yet as the hollow axle of the wheel _m_ is not fastened to the axle _h_,

by the screw _n_, these wheels will revolve without carrying round the

frame _f_.

M. Kuhlmann, Professor of Chemistry at Lille, having been called upon

several times by the courts of justice to examine by chemical processes

bread suspected of containing substances injurious to health, collected

some interesting facts upon the subject, which were published under the

direction of the central council of salubrity of the department _du

Nord_.

For some time public attention had been drawn to an odious fraud

committed by a great many bakers in the north of France and in

Belgium,--the introduction of a certain quantity of sulphate of copper

into their bread. When the flour was made from bad grain this

adulteration was very generally practised, as was proved by many

convictions and confessions of the guilty persons. When the dough does

not rise well in the fermentation (_le pain pousse plat_), this

inconvenience was found to be obviated by the addition of blue vitriol,

which was supposed also to cause the flour to retain more water. The

quantity of blue water added is extremely small, and it is never done in

presence of strangers, because it is reckoned a valuable secret. It

occasions no economy of yeast, but rather the reverse. In a litre (about

a quart) of water, an ounce of sulphate of copper is dissolved; and of

this solution a wine-glass full is mixed with the water necessary for 50

quartern or 4 pound loaves.

M. Kuhlmann justly observes that there can be no safety whatever to the

public when such a practice is permitted, because ignorance and avarice

are always apt to increase the quantity of the poisonous water. In

analyses made by him and his colleagues, portions of bread were several

times found so impregnated with the above salt that they had acquired a

blue colour, and presented occasionally even small crystals of the

sulphate. By acting on the poisoned bread with distilled water and

testing the water with ferro-cyanate (prussiate) of potash, the reddish

brown precipitate or tint characteristic of copper will appear even with

small quantities. Should the noxious impregnation be still more minute,

the bread should be treated with a very dilute nitric-acid, either

directly, or after incineration in a platinum capsule, and the solution,

when concentrated by evaporation, should be tested by the ferro-cyanate

of potash. In this way, a one seventy thousandth part of sulphate of

copper may be detected.

M. Kuhlmann deduces, from a series of experiments on baking with various

small quantities of sulphate of copper, that this salt exercises an

extremely energetic action upon the fermentation and rising of the

dough, even when not above one seventy thousandth part of the weight of

the bread is employed; or one grain of sulphate for ten pounds of bread.

The proportion of the salt which makes the bread rise best is one twenty

thousandth, or one grain in three pounds of bread. If much more of the

sulphate be added, the bread becomes moist, less white, and acquires a

peculiar disagreeable smell like that of leaven. The increase of weight

by increased moisture may amount to one sixteenth without the bread

appearing softer, in consequence of the solidifying quality of the

copper; for the acid does not seem to have any influence; as neither

sulphate of soda, sulphate of iron, nor sulphuric acid have any

analogous power. Alum operates like blue vitriol on bread, but larger

quantities of it are required. It _keeps water_, and _raises well_, to

use the bakers’ terms.

When alum is present in bread it may be detected by treating the bread

with distilled water, filtering the water first through calico, and next

through filtering paper, till it becomes clear; then dividing it into

two portions, and into the one pouring a few drops of nitrate or muriate

of barytes, and into the other a few drops of water of ammonia. In the

former a heavy white precipitate indicating sulphuric acid will appear,

and in the latter a light precipitate of alumina, redissoluble by a few

drops of solution of caustic potash.

When chalk or Paris plaster is used to sophisticate flour, they may be

best detected by incinerating the bread made of it, and examining the

ashes with nitric acid which will dissolve the chalk with effervescence,

and the Paris plaster without. In both cases the calcareous matter may

be demonstrated in the solution, by oxalic acid, or better by oxalate of

ammonia.

In baking puff-paste the dough is first kneaded along with a certain

quantity of butter, then rolled out into a thin layer, which is coated

over with butter, and folded face-wise many times together, the upper

and under surfaces being made to correspond. This stratified mass is

again rolled out into a thin layer, its surface is besmeared with

butter, and then it is folded face-wise as before. When this process is

repeated ten or a dozen times, the dough will consist of many hundred

parallel laminæ, with butter interposed between each pair of plates.

When a moderately thick mass of this is put into the oven, the elastic

vapour disengaged from the water and the butter, diffuses itself between

each of the thin laminæ, and causes them to swell into what is properly

called puff-paste, being an assemblage of thin membranes, each dense in

itself, but more or less distinct from the other, and therefore forming

apparently but not really light bread.

One of the most curious branches of the baker’s craft is the manufacture

of gingerbread, which contains such a proportion of molasses, that it

cannot be fermented by means of yeast. Its ingredients are flour,

molasses or treacle, butter, common potashes, and alum. After the butter

is melted, and the potashes and alum are dissolved in a little hot

water, these three ingredients, along with the treacle, are poured among

the flour, which is to form the body of the bread. The whole is then

incorporated by mixture and kneading into a stiff dough. Of these five

constituents the alum is thought to be the least essential, although it

makes the bread lighter and crisper, and renders the process more rapid;

for gingerbread dough requires to stand over several days, sometimes 8

or 10, before it acquires that state of porosity which qualifies it for

the oven. The action of the treacle and alum on the potashes in evolving

carbonic acid, seems to be the gasefying principle of gingerbread; for

if the carbonate of potash is withheld from the mixture, the bread, when

baked, resembles in hardness a piece of wood.

Treacle is always acidulous. Carbonate of magnesia and soda may be used

as substitutes for the potashes. Dr. Colquhoun has found that carbonate

of magnesia and tartaric acid may replace the potashes and the alum with

great advantage, affording a gingerbread fully more agreeable to the

taste, and much more wholesome than the common kind, which contains a

notable quantity of potashes. His proportions are one pound of flour, a

quarter of an ounce of carbonate of magnesia, and one eighth of an ounce

of tartaric acid; in addition to the treacle, butter, and aromatics as

at present used. The acid and alkaline earth must be well diffused

through the whole dough. The magnesia should, in fact, be first of all

mixed with the flour. Pour the melted butter, the treacle, and the acid

dissolved in a little water all at once among the flour, and knead into

a consistent dough, which being set aside for half an hour or an hour

will be ready for the oven, and should never be kept unbaked more than 2

or 3 hours. The following more complete recipe is given by Dr.

Colquhoun, for making thin gingerbread cakes:--

Flour 1 lb.

Treacle 0-1/2

Raw sugar 0-1/4

Butter 2 oz.

Carbon. magnesia 0-1/4

Tartaric acid 0-1/8

Ginger 0-1/8

Cinnamon 0-1/8

Nutmeg 1

This compound has rather more butter than common thin gingerbread.

I shall here insert a passage from my Dictionary of Chemistry as

published in 1821; as it may prove interesting to many of my present

readers.

“Under _Process of Baking_, in the Supplement to the Encyclopedia

Britannica, we have the following statement:--‘An ounce of alum is then

dissolved over the fire in a tin pot, and the solution poured into a

large tub, called by the bakers the seasoning-tub. Four pounds and a

half of salt are likewise put into the tub, and a pailful of hot

water.’--_Foot note on this passage._--‘In London, where the goodness of

bread is estimated entirely by its whiteness, it is usual with those

bakers who employ flour of an inferior quality, to add as much alum as

common salt to the dough; or, in other words, the quantity of salt added

is diminished one half, and the deficiency supplied by an equal weight

of alum. This improves the look of the bread very much, rendering it

much whiter and firmer.’”

In a passage which we shall presently quote, our author represents the

bakers of London in a conspiracy to supply the citizens with bad bread.

We may hence infer that the full allowance he assigns of 2-1/4 pounds of

alum for every 2-1/4 pounds of salt, will be adopted in converting the

sack of flour into loaves. But as a sack of flour weighs 280 pounds, and

furnishes on an average 80 quartern loaves, we have 2-1/4 pounds divided

by 80, or (15750 grains/80) = 197 grains, for the quantity present, by

this writer, in a London quartern loaf. Yet in the very same page (39th

of vol. ii.) we have the following passage: “Alum is not added by all

bakers. The writer of this article has been assured by several bakers of

respectability, both in Edinburgh and Glasgow, on whose testimony he

relies, and who made excellent bread, that they never employed any alum.

The reason for adding it given by the London bakers is, that it renders

the bread whiter, and enables them to separate readily the loaves from

each other. This addition has been alleged by medical men, and is

considered by the community at large, as injurious to the health, by

occasioning constipation. But if we consider the small quantity of this

salt added by the baker, not quite 5-1/2 grains to a quartern loaf, we

will not readily admit these allegations. Suppose an individual to eat

the seventh part of a quartern loaf a day, he would only swallow

eight-tenths of a grain of alum, or, in reality, not quite so much as

half a grain; for one half of this salt consists of water. It seems

absurd to suppose that half a grain of alum, swallowed at different

times during the course of a day, should occasion constipation.” Is it

not more absurd to state 2-1/4 pounds or 36 ounces, as the alum

adulteration of a sack of flour by the London bakers, and within a few

periods to reduce the adulteration to one ounce?

That this voluntary abstraction of 35/36 of the alum, and substitution

of superior and more expensive flour is not expected by him from the

London bakers, is sufficiently evident from the following story. It

would appear that one of his friends had invented a new yeast for

fermenting dough, by mixing a quart of beer barm with a paste made of

ten pounds of flour and two gallons of boiling water, and keeping this

mixture warm for six or eight hours.

“Yeast made in this way,” says he, “answers the purposes of the baker

much better than brewers’ yeast, because it is clearer, and free from

the hop mixture which sometimes injures the yeast of the brewer. Some

years ago the bakers of London, sensible of the superiority of this

artificial yeast, invited a company of manufacturers from Glasgow to

establish a manufactory of it in London, and promised to use no other.

About 5,000_l._ accordingly was laid out on buildings and materials, and

the manufactory was begun on a considerable scale. The ale-brewers,

finding their yeast, for which they had drawn a good price, lie heavy on

their hands, invited _all_ the journeymen bakers to their cellars, gave

them their full of ale, and promised to regale them in that manner every

day, provided they would force their masters to take all their yeast

from the ale-brewers. The journeymen accordingly declared, in a body,

that they would work no more for their masters unless they gave up

taking any more yeast from the manufactory. The masters were obliged to

comply; the new manufactory was stopped, and the inhabitants of London

were obliged to continue to eat worse bread, because it was the interest

of the ale-brewers to sell the yeast. Such is the influence of

journeymen bakers in the metropolis of England!”

This doleful diatribe seems rather extravagant; for surely beer yeast

can derive nothing noxious to a porter drinking people, from a slight

impregnation of hops; while it must form probably a more energetic

ferment than the fermented paste of the new company, which at any rate

could be prepared in six or eight hours by any baker who found it to

answer his purpose of making a pleasant-eating bread. But it is a very

serious thing for a lady or gentleman of sedentary habits, or infirm

constitution, to have their digestive process daily vitiated by damaged

flour, whitened with 197 grains of alum per quartern loaf. Acidity of

stomach, indigestion, flatulence, headaches, palpitation, costiveness,

and urinary calculi may be the probable consequences of the habitual

introduction of so much acidulous and acescent matter.

I have made many experiments upon bread, and have found the proportion

of alum very variable. Its quantity seems to be proportional to the

badness of the flour; and hence when the best flour is used, no alum

need be introduced. That alum is not necessary for giving bread its

utmost beauty, sponginess, and agreeableness of taste, is undoubted;

since the bread baked at a very extensive establishment in Glasgow, in

which about 20 tons of flour were regularly converted into loaves in the

course of a week, united every quality of appearance with an absolute

freedom from that acido-astringent drug. Six pounds of salt were used

for every sack of flour; which, from its good quality, generally

afforded 83 or 84 quartern loaves of the legal weight of four pounds

five ounces and a half each. The loaves lost nine ounces in the oven.

Every baker ought to be able to analyse his flour. He may proceed as

follows:--A ductile paste is to be made with a pound of the flour and a

sufficient quantity of water, and left at rest for an hour; then having

tied across a bowl a piece of silken sieve-stuff, a little below the

surface of the water in the bowl, the paste is to be laid upon the sieve

on a level with the water, and kneaded tenderly with the hand, so as

merely to wash the starchy particles out of it. This portion of the

flour gets immediately diffused through the water, some of the other

constituents dissolve, and the gluten alone remains upon the filter. The

water must be several times renewed till it ceases to become milky. The

last washings of the gluten are made out of the sieve.

The whole of the turbid washings are to be put into a tall conical glass

or stoneware vessel, and allowed to remain at rest, in a cool place,

till they deposit the starch. The clear supernatant liquor is then

decanted off. The deposit consists of starch, with a little gluten. It

must be washed till the water settles over it quite clear, and then it

is to be dried.

The filtered waters being evaporated, at a boiling heat, discover flocks

floating through them, which have been supposed by some to be albumen,

and by others gluten. At last, phosphate of lime precipitates. When the

residuum has assumed a syrupy consistence in the cold, it is to be mixed

with alcohol, in order to dissolve out its sugar. Cold water being added

to what remains, effects a solution of the mucilage, and leaves the

insoluble azotized matter with the phosphate of lime.

By this mode of analysis a minute portion of resin may remain in the

gluten and in the washing water; the gluten retains also a small

proportion of a fixed oil, and a volatile principle, which may be

removed by alcohol. If we wish to procure the resin alone, we must first

of all treat the flour, well dried, with alcohol.

When corn flour, poor in gluten, is to be analyzed, the dough must be

inclosed in a linen bag, kneaded with water, and washed in that state.

In analyzing barley-meal by the above process, _hordeine_, mixed with

common starch, is obtained: they may be separated by boiling water,

which dissolves the starch, and leaves the hordeine under the aspect of

saw-dust.

[Illustration: 170 171]

_Fig._ 171. is the plan of a London baker’s oven, fired with coal fuel.

_Fig._ 170. is the longitudinal section.

_a_, the body of the oven; _b_, the door; _c_, the fire-grate and

furnace; _d_, the smoke flue; _e_, the flue above the door, to carry off

the steam and hot air, when taking out the bread; _f_, recess below the

door, for receiving the dust; _g_, damper plate to shut off the steam

flue; _h_, damper plate to shut off smoke flue, after the oven has come

to its proper heat; _i_, a small iron pan over the fire-place _c_, for

heating water; _k_, ash-pit below the furnace.

[Illustration: 172]

_Fig._ 172. is the front view; the same letters refer to the same

objects in all the figures.

The flame and burnt air of the fire at _c_, sweep along the bottom of

the oven by the right hand side, are reflected from the back to the left

hand side, and thence escape by the flue _d_; (see plan _fig._ 171).

Whenever the oven has acquired the proper degree of heat, the fire is

withdrawn, the flues are closed by the damper plates, and the lumps of

fermented dough are introduced.

BRECCIA, an Italian term, used by mineralogists and architects to

designate such compound stony masses, natural or artificial, as consist

of hard rocky fragments of considerable size, united by a common cement.

When these masses are formed of small rounded pebbles, the conglomerate

is called a pudding-stone, from a fancied resemblance to plum pudding.

_Concrete_, now so much used for the foundations of large buildings, is

a factitious breccia, or pudding-stone. See CONCRETE.

BREWING. (_Brasser_, Fr.; _Brauen_, Germ.) The art of making beer, which

see.

BRICK. (_Brique_, Fr.; _Backsteine_, _ziegelsteine_, Germ.) A solid,

commonly rectangular, composed of clay, hardened by heat, and intended

for building purposes. The natural mixture of clay and sand, called

_loam_, as well as marl, which consists of lime and clay, with little or

no sand, constitutes also a good material for making bricks. The poorer

the marl is in lime, the worse adapted it is for agricultural purposes,

and the better for the brick manufacturer, being less liable to fuse in

his kiln. When a natural compound of silica and clay can be got nearly

free from lime and magnesia, it forms a kind of bricks very refractory

in the furnace, hence termed _fire-bricks_. Such a material is the

slate-clay, _schieferthon_, of our coal measures, found abundantly, and

of excellent quality, at Stourbridge, and in the neighbourhood of

Newcastle and Glasgow. The London brickmakers add to the clay about one

third of coal ashes obtained from the kitchen dust-holes; so that when

the bricks are put into the kiln, the quantity of coaly matter attached

to their surface, serves to economise fuel, and makes them less apt to

shrink in the fire; though they are less compact, and probably less

durable, than the bricks made in the coal districts of England.

The general process of brick-making consists in digging up the clay in

autumn; exposing it, during the whole winter, to the frost, and the

action of the air, turning it repeatedly, and working it with the spade;

breaking down the clay lumps in spring, throwing them into shallow pits,

to be watered and soaked for several days. The next step is to temper

the clay, which is generally done by the treading of men or oxen. In the

neighbourhood of London, however, this process is performed in a

horse-mill. The kneading of the clay is, in fact, the most laborious but

indispensable part of the whole business; and that on which, in a great

measure, the quality of the bricks depends. All the stones, particularly

the ferruginous, calcareous, and pyritous kinds, should be removed, and

the clay worked into a homogeneous paste, with as little water as

possible.

The earth, being sufficiently kneaded, is brought to the bench of the

moulder, who works the clay into a mould made of wood or iron, and

strikes off the superfluous matter. The bricks are next delivered from

the mould, and ranged on the ground; and when they have acquired

sufficient firmness to bear handling, they are dressed with a knife, and

staked or built up in long dwarf walls, thatched over, and left to dry.

An able workman will make, by hand, 5,000 bricks in a day.

The different kinds of bricks made in England are principally _place

bricks_, _gray and red stocks_, _marl facing bricks_, and _cutting

bricks_. The place bricks and stocks are used in common walling. The

marls are made in the neighbourhood of London, and used in the outside

of buildings; they are very beautiful bricks, of a fine yellow colour,

hard, and well burnt, and, in every respect, superior to the stocks. The

finest kind of marl and red bricks, called cutting bricks, are used in

the arches over windows and doors, being rubbed to a centre, and gauged

to a height.

In France attempts were long ago made to substitute animals and machines

for the treading of men’s feet in the clay-kneading pit; but it was

found that their schemes could not replace, with advantage, human

labour, where it is so cheap, particularly for separating the stones and

heterogeneous matters from the loam. The more it is worked, the denser,

more uniform, and more durable, the bricks which are made of it. A good

French workman, in a day’s labour of 12 or 13 hours, it has been said,

is able to mould from 9,000 to 10,000 bricks, 9 inches long, 4-1/2

inches broad, and 2-1/4 thick; but he must have good assistants under

him. In many brickworks near Paris, screw-presses are now used for

consolidating the bricks and paving tiles in their moulds. M. Mollerat

employed the hydraulic press for the purpose of condensing pulverized

clay, which, after baking, formed beautiful bricks; but the process was

too tedious and costly. An ingenious contrivance for moulding bricks

mechanically, is said to be employed near Washington, in America. This

machine moulds 30,000 in a day’s work of 12 hours, with the help of one

horse, yoked to a gin wheel, and the bricks are so dry when discharged

from their moulds, as to be ready for immediate burning. The machine is

described, with figures, in the _Bulletin de la Société d’Encouragement_

for 1819, p. 361. _See further on, an account of our recent patents._

Bricks, in this country, are generally baked either in a clamp or in a

kiln. The latter is the preferable method, as less waste arises, less

fuel is consumed, and the bricks are sooner burnt. The kiln is usually

13 feet long, by 10-1/2 feet wide, and about 12 feet in height. The

walls are one foot two inches thick, carried up a little out of the

perpendicular, inclining towards each other at the top. The bricks are

placed on flat arches, having holes left in them resembling

lattice-work; the kiln is then covered with pieces of tiles and bricks,

and some wood put in, to dry them with a gentle fire. This continues two

or three days before they are ready for burning, which is known by the

smoke turning from a darkish colour to transparent. The mouth or mouths

of the kiln are now dammed up with a _shinlog_, which consists of pieces

of bricks piled one upon another, and closed with wet brick earth,

leaving above it just room sufficient to receive a faggot. The faggots

are made of furze, heath, brake, fern, &c., and the kiln is supplied

with these until its arches look white, and the fire appears at the top;

upon which the fire is slackened for an hour, and the kiln allowed

gradually to cool. This heating and cooling is repeated until the bricks

be thoroughly burnt, which is generally done in 48 hours. One of these

kilns will hold about 20,000 bricks.

Clamps are also in common use. They are made of the bricks themselves,

and generally of an oblong form. The foundation is laid with _place

brick_, or the driest of those just made, and then the bricks to be

burnt are built up, tier upon tier, as high as the clamp is meant to be,

with two or three inches of breeze or cinders strewed between each layer

of bricks, and the whole covered with a thick stratum of breeze. The

fireplace is perpendicular, about three feet high, and generally placed

at the west end; and the flues are formed by gathering or arching the

bricks over, so as to leave a space between each of nearly a brick wide.

The flues run straight through the clamp, and are filled with wood,

coals, and breeze, pressed closely together. If the bricks are to be

burnt off quickly, which may be done in 20 or 30 days, according as the

weather may suit, the flues should be only at about six feet distance;

but if there be no immediate hurry, they may be placed nine feet

asunder, and the clamp left to burn off slowly.

Floating bricks are a very ancient invention: they are so light as to

swim in water; and Pliny tells us, that they were made at Marseilles; at

Colento, in Spain; and at Pittane, in Asia. This invention, however, was

completely lost, until M. Fabbroni published a discovery of a method to

imitate the floating bricks of the ancients. According to Posidonius,

these bricks are made of a kind of argillaceous earth, which was

employed to clean silver plate. But as it could not be our tripoli,

which is too heavy to float in water, M. Fabbroni tried several

experiments with mineral agaric, guhr, lac-lunæ, and fossil meal, which

last was found to be the very substance of which he was in search. This

earth is abundant in Tuscany, and is found near Casteldelpiano, in the

territories of Sienna. According to the analysis of M. Fabbroni, it

consists of 55 parts of siliceous earth, 15 of magnesia, 14 of water, 12

of alumina, 3 of lime, and 1 of iron. It exhales an argillaceous odour,

and, when sprinkled with water, throws out a light whitish smoke. It is

infusible in the fire; and, though it loses about an eighth part of its

weight, its bulk is scarcely diminished. Bricks composed of this

substance, either baked or unbaked, float in water; and a twentieth part

of clay may be added to their composition without taking away their

property of swimming. These bricks resist water, unite perfectly with

lime, are subject to no alteration from heat or cold, and the baked

differ from the unbaked only in the sonorous quality which they have

acquired from the fire. Their strength is little inferior to that of

common bricks, but much greater in proportion to their weight; for M.

Fabbroni found, that a floating brick, measuring 7 inches in length,

4-1/2 in breadth, and one inch eight lines in thickness, weighed only

14-1/4 ounces; whereas a common brick weighed 5 pounds, 6-3/4 ounces.

The use of these bricks may be very important in the construction of

powder magazines and reverberatory furnaces, as they are such bad

conductors of heat, that one end may be made red hot while the other is

held in the hand. They may also be employed for buildings that require

to be light; such as cooking-places in ships, and floating batteries,

the parapets of which would be proof against red-hot bullets.

The following plan of a furnace or kiln for burning tiles has been found

very convenient:--

[Illustration: 173 174 175]

_Fig._ 173., front view, A A, B B, the solid walls of the furnace; _a a

a_, openings to the ash-pit, and the draught hole; _b b b_, openings for

the supply of fuel, furnished with a sheet-iron door. _Fig._ 174. Plan

of the ash-pits and air channels _c c c_. The principal branch of the

ash-pit D D D, is also the opening for taking out the tiles, after

removing the grate; E the smoke flue. _Fig._ 175. Plan of the kiln seen

from above. The grates H H H. The tiles to be fired are arranged upon

the spaces _f f f f_.

[Illustration: 176]

_Fig._ 176. is the plan and section of one of the grates upon a much

larger scale than in the preceding figures.

_Mechanical brick moulding._--Messrs. Lyne and Stainford obtained in

August, 1825, a patent for a machine for making a considerable number of

bricks at one operation. It consists, in the first place, of a

cylindrical pug-mill of the kind usually employed for comminuting clay

for bricks and tiles, furnished with rotatory knives, or cutters, for

breaking the lumps and mixing the clay with the other materials of which

bricks are commonly made. Secondly, of two movable moulds, in each of

which fifteen bricks are made at once; these moulds being made to travel

to and fro in the machine for the purpose of being alternately brought

under the pug-mill to be fitted with the clay, and then removed to

situations where plungers are enabled to act upon them. Thirdly, in a

contrivance by which the plungers are made to descend, for the purpose

of compressing the material and discharging it from the mould in the

form of bricks. Fourthly, in the method of constructing and working

trucks which carry the receiving boards, and conduct the bricks away as

they are formed.

[Illustration: 177]

_Fig._ 177. exhibits the general construction of the apparatus; both

ends of which being exactly similar, little more than half of the

machine is represented. _a_ is the cylindrical pug-mill, shown partly in

section, which is supplied with the clay and other materials from a

hopper above; _b b_, are the rotatory knives or cutters, which are

attached to the vertical shaft, and being placed obliquely, press the

clay down towards the bottom of the cylinder, in the act of breaking and

mixing it as the shaft revolves. The lower part of the cylinder is open;

and immediately under it the mould is placed in which the bricks are to

be formed. These moulds run to and fro upon ledges in the side frames of

the machine; one of the moulds only can be shown by dots in the figure,

the side rail intervening: they are situated at _c c_ and are formed of

bars of iron crossing each other, and encompassed with a frame. The

mould resembles an ordinary sash window in its form, being divided into

rectangular compartments (fifteen are proposed in each) of the

dimensions of the intended bricks, but sufficiently deep to allow the

material, after being considerably pressed in the mould, to leave it,

when discharged, of the usual thickness of a common brick.

The mould being open at top and bottom, the material is allowed to pass

into it, when situated exactly under the cylinder; and the lower side of

the mould, when so placed, is to be closed by a flat board _d_,

supported by the truck _e_, which is raised by a lever and roller

beneath, running upon a plane rail with inclined ends.

The central shaft _f_, is kept in continual rotatory motion by the

revolution of the upper horizontal wheel _g_, of which it is the axis;

and this wheel may be turned by a horse yoked to a radiating arm, or by

any other means. A part of the circumference of the wheel _g_, has teeth

which are intended at certain periods of its revolution to take into a

toothed pinion, fixed upon the top of a vertical shaft _h h_. At the

lower part of this vertical shaft, there is a pulley _i_, over which a

chain is passed that is connected to the two moulds _c_, and to the

frame in which the trucks are supported; by the rotation of the vertical

shaft, the pulley winds a chain, and draws the moulds and truck frames

along.

The clay and other material having been forced down from the cylinder

into the mould, the teeth of the horizontal wheel _g_ now come into geer

with the pinion upon _h_, and turn it and the shaft and pulley _i_, by

which the chain is wound, and the mould at the right hand of the machine

brought into the situation shown in the figure; a scraper or edge-bar

under the pug-mill having levelled the upper face of the clay in the

mould, and the board _d_, supported by the truck _e_, formed the flat

under side.

The mould being brought into this position, it is now necessary to

compress the materials, which is done by the descent of the plungers _k

k_. A friction-roller _l_, pendant from the under side of the horizontal

wheel as that wheel revolves, comes in contact with an inclined plane,

at the top of the shaft of the plungers; and, as the friction-roller

passes over this inclined plane, the plungers are made to descend into

the mould, and to compress the material; the resistance of the board

beneath causing the clay to be squeezed into a compact state. When this

has been effectually accomplished, the further descent of the plungers

brings a pin _m_, against the upper end of a quadrant catch-lever _n_,

and, by depressing this quadrant, causes the balance-lever upon which

the truck is now supported to rise at that end, and to allow the truck

with the board _d_ to descend, as shown by dots; the plungers at the

same time forcing out the bricks from the moulds, whereby they are

deposited upon the board _d_; when, by drawing the truck forward out of

the machine, the board with the bricks may be removed, and replaced by

another board. The truck may then be again introduced into the machine,

ready to receive the next parcel of bricks.

By the time that the discharge of the bricks from this mould has been

effected, the other mould under the pug cylinder has become filled with

the clay, when the teeth of the horizontal wheel coming round, take into

a pinion upon the top of a vertical shaft exactly similar to that at

_h_, but at the reverse end of the machine, and cause the moulds and the

frame supporting the trucks to be slidden to the left end of the

machine; the upper surface of the mould being scraped level in its

progress, in the way already described. This movement brings the

friction-wheel _o_, up the inclined plane, and thereby raises the truck

with the board to the under side of the mould, ready to receive another

supply of clay; and the mould at the left-hand side of the machine being

now in its proper situation under the plungers, the clay becomes

compressed, and the bricks discharged from the mould in the way

described in the former instance; when this truck being drawn out, the

bricks are removed to be dried and baked, and another board is placed in

the same situation. There are boxes _p_, upon each side of the pug

cylinder containing sand, at the lower parts of which small sliders are

to be opened (by contrivances not shown in the figure) as the mould

passes under them, for the purpose of scattering sand upon the clay in

the mould to prevent its adhering to the plungers. There is also a rack

and toothed sector, with a balance weight connected to the inclined

plane at the top of the plunger-rods, for the purpose of raising the

plunger after the friction-roller has passed over it. And there is a

spring acting against the back of the quadrant-catch for the purpose of

throwing it into its former situation, after the pin of the plunger has

risen.

One of the latest, and apparently most effective machines for

brick-making, is that patented by Mr. Edward Jones of Birmingham, in

August 1835. His improvements are described under four heads; the first

applies to a machine for moulding the earth into bricks in a circular

frame-plate horizontally, containing a series of moulds or rectangular

boxes, standing radially round the circumference of the circular frame,

into which boxes successively the clay is expressed from a stationary

hopper as the frame revolves, and after being so formed, the bricks are

successively pushed out of their boxes, each by a piston, acted upon by

an inclined plane below. The second head of the specification describes

a rectangular horizontal frame, having a series of moulding boxes placed

in a straight range, which are acted upon for pressing the clay by a

corresponding range of pistons fixed in a horizontal frame, worked up

and down by rods extending from a rotatory crank shaft, the moulding

boxes being allowed to rise for the purpose of enabling the pistons to

force out the bricks when moulded, and leave them upon the bed or board

below. The third head applies particularly to the making of tiles, for

the flooring of kilns in which malt or grain is to be dried. There is in

this contrivance a rectangular mould, with pointed pieces standing up

for the purpose of producing air-holes through the tiles as they are

moulded, which is done by pressing the clay into the moulds upon the

points, and scraping off the superfluous matter at top by hand. The

fourth or last head applies to moulding chimney pots in double moulds,

which take to pieces for the purpose of withdrawing the pot when the

edges of the slabs or sides are sufficiently brought into contact.

“The drawing which accompanies the specification very imperfectly

represents some parts of the apparatus, and the description is still

more defective; but as we are acquainted with the machinery, we will

endeavour to give it an intelligible form, and quote those parts of the

specification which point the particular features of novelty proposed to

be claimed by the patentee as his invention, under the several

heads.”[13]

[13] Mr. Newton, in his London Journal, February, 1837.

[Illustration: 178 179]

_Fig._ 178. represents, in elevation, the first-mentioned machine for

moulding bricks. The moulds are formed in the face of a circular plate

or wheel _a a_, a portion of the upper surface of which is represented

in the horizontal view, _fig._ 179. Any convenient number of these

moulds are set radially in the wheel, which is mounted upon a central

pivot, supported by the masonry _b b_. There is a rim of teeth round the

outer edge of the wheel _a a_, which take into a pinion _c_, on a shaft

connected to the first mover; and by these means the wheel _a_, with the

moulding boxes, is made to revolve horizontally, guided by arms with

anti-friction rollers, which run round a horizontal plate _a a_, fixed

upon the masonry.

A hopper _e_, filled with the brick earth shown with one of the moulding

boxes in section, is fixed above the face of the wheel in such a way,

that the earth may descend from the hopper into the several moulding

boxes as the wheel passes round under it; the earth being pressed into

the moulds, and its surface scraped off smooth by a conical roller _f_,

in the bottom of the hopper.

Through the bottom of each moulding box there is a hole for the passage

of a piston rod _g_, the upper end of which rod carries a piston with a

wooden pallet upon it, acting within the moulding box; and the lower end

of this rod has a small anti-friction roller which, as the wheel _a_

revolves, runs round upon the face of an oblique ring or inclined way _h

h_, fixed upon the masonry.

The clay is introduced into the moulding boxes from the hopper, fixed

over the lowest part of the inclined way _h_, and it will be perceived

that as the wheel revolves, the piston rods _g_, in passing up the

inclined way, will cause the pistons to force the new-moulded bricks,

with their pallet or board under them, severally up the mould, into the

situation shown at _i_, in _fig._ 178., from whence they are to be

removed by hand. Fresh pallets being then placed upon the several

pistons, they, with the moulds, will be ready for moulding fresh bricks,

when, by the rotation of the wheel _a_, they are severally brought under

the hopper, the pistons having sunk to the bottoms of their boxes, as

the piston rods passed down the other side of the inclined way _h_.

The patentee says, after having described the first head of his

invention, he would have it understood that the same may be varied

without departing from the main object of the invention; viz. that of

arranging a series of moulds when worked by means of an inclined track,

and in such manner that bricks, tiles, or other articles made of brick

earth, may be capable of being formed in a mould with pallets or boards

laid within the moulds, and constituting the bottoms thereof, the bricks

being removed from out of the moulds, with the pallets or boards under

them, as above described. “I do not, therefore, confine myself to the

precise arrangement of the machine here shown, though it is the best

with which I am acquainted for the purpose.”

[Illustration: 180 181]

The second head of the invention is another construction of apparatus

for moulding bricks, in this instance, in a rectangular frame. _Fig._

180. is a front elevation of the machine; _fig._ 181., a section of the

same taken transversely. _a a_ is the standard frame-work and bed on

which the bricks are to be moulded. Near the corners of this standard

frame-work, four vertical pillars _b b_ are erected, upon which pillars

the frame of the moulding boxes _c_, slides up and down, and also the

bar _d_, carrying the rods of the pistons _e e e_. These pistons are for

the purpose of compressing the clay in the moulding box, and therefore

must stand exactly over and correspond with the respective moulds in the

frame _c_ beneath.

The sliding frame _c_, constituting the sides and ends of the moulding

boxes, is supported at each end by an upright sliding rod _f_, which

rods pass through guides fixed to the sides of the standard frame _a a_,

and at the lower end of each there is a roller, bearing upon the levers

_g_, on each side of the machine, but seen only in _fig._ 181., which

levers, when depressed, allow the moulding boxes to descend, and rest

upon the bed or table of the machine _h h_.

In this position of the machine resting upon the bed or table, the

brick-earth is to be placed upon, and spread over, the top of the frame

_c_, by the hands of workmen, when the descent of the plunger or pistons

_e e e_, will cause the earth to be forced into the moulds, and the

bricks to be formed therein. To effect this, rotatory power is to be

applied to the toothed wheel _i_, fixed on the end of the main driving

crank shaft _k k_, which on revolving will, by means of the crank rods

_l l_, bring down the bar _a_, with the pistons or plungers _e e e_, and

compress the earth compactly into the moulds, and thereby form the

bricks.

When this has been done, the bricks are to be released from the moulds

by the moulding frame _c_ rising up from the bed, as shown in _fig._

180., the pistons still remaining depressed, and bearing upon the upper

surfaces of the bricks. The moulding frame is raised by means of cams

_m_, upon the crank shaft, which at this part of the operation are

brought under the levers _g_, for the purpose of raising the cams and

the sliding rods _f_, into the position shown in _fig._ 181.

The bricks having been thus formed and released from their moulds, they

are to be removed from the bed of the machine by pushing forward, on the

front side, fresh boards or pallets, which of course will drive the

bricks out upon the other side, whence they are to be removed by hand.

There is to be a small hole in the centre of each pallet, and also in

the bed, for the purpose of allowing any superfluous earth to be pressed

through the moulding boxes when the pistons descend. And in order to cut

off the projecting piece of clay which would be thus formed on the

bottom of the brick, a knife-edge is in some way connected to the bed of

the machine; and as the brick slides over it, the knife separates the

protuberant lump: but the particular construction of this part of the

apparatus is considered to be of little importance; and the manner of

effecting the object is not clearly stated in the specification.

The patentee proposes a variation in this construction, which he

describes in these words: “It will be evident that in place of having

the moulds to rise, they may, by suitable arrangements, be made to

descend below the bricks. In this case, in place of the boards,

stationary blocks to receive the pallets must be fixed on the bed of the

machine, and these blocks must be shaped in such a manner as to allow of

the moulds passing over them; and then it will be desirable to use the

first part of my improvements, that of having the pallets within the

moulds at the time of moulding the bricks; or in case of working with

exceedingly stiff brick-earth, the pallets may be dispensed with.” In

1835, 1,380,279,065 bricks paid duty in the United Kingdom; the revenue

from which was 405,580_l._ 6_s._ 3_d._

BRIMSTONE. (_Soufre_, Fr.; _Schwefel_, Germ.) Sulphur, which see.

BRITISH GUM. The trivial name given to starch, altered by a slight

calcination in an oven, whereby it assumes the appearance and acquires

the properties of gum, being soluble in cold water, and forming in that

state a paste well adapted to thicken the colours of the calico printer.

See STARCH.

BROMINE, one of the archæal elements, which being developed from its

combinations at the positive pole of the voltaic circuit, has been

therefore deemed to be idio-electro-positive like oxygen and chlorine.

It derives its name from its nauseous smell, Βρῶμος, _fœtor_. It occurs

in various saline springs on the continent of Europe, in those of Ashby

de la Zouche, and some others in England; in the lake Asphaltites, in

sponges, in some marine plants, in an ore of zinc, and in the cadmium of

Silesia. At ordinary temperatures it is liquid, of a dark brown colour

in mass, but of a hyacinth-red in thin layers. Its smell is rank and

disagreeable, somewhat like that of chlorine. It has a very caustic

taste. Its specific gravity is 2·966. Applied to the skin it colours it

deep yellow and corrodes it. One drop put within the bill of a bird

suffices to kill it. It combines with oxygen with feeble affinity,

forming bromic acid. Its attraction for hydrogen being far more

energetic, it forms therewith a strong acid, the hydrobromic.

Bromine dissolves very sparingly in water, but it is very soluble in

alcohol and ether. It combines with carbone, phosphorus, sulphur, and

chlorine, as well as with most of the metals. From its scarcity it has

not hitherto been applied to any purpose in the arts, but it is supposed

to possess powerful discutient effects upon scrophulous and other

glandular tumours, whence the waters containing it are prescribed as an

internal and external remedy in such forms of disease.

BRONZE. A compound metal consisting of copper and tin, to which

sometimes a little zinc and lead are added. This alloy is much harder

than copper, and was employed by the ancients to make swords, hatchets,

&c., before the method of working iron was generally understood. The art

of casting bronze statues may be traced to the most remote antiquity,

but it was first brought to a certain degree of refinement by Theodoros

and Rœcus of Samos, about 700 years before the Christian era, to whom

the invention of modelling is ascribed by Pliny. The ancients were well

aware that by alloying copper with tin, a more fusible metal was

obtained, that the process of casting was therefore rendered easier, and

that the statue was harder and more durable; and yet they frequently

made them of copper nearly pure, because they possessed no means of

determining the proportions of their alloys, and because by their mode

of managing the fire, the copper became refined in the course of

melting, as has happened to many founders in our own days. It was during

the reign of Alexander that bronze statuary received its greatest

extension, when the celebrated artist Lysippus succeeded by new

processes of moulding and melting to multiply groups of statues to such

a degree that Pliny called them the _mob of Alexander_. Soon afterwards

enormous bronze colossuses were made, to the height of towers, of which

the isle of Rhodes possessed no less than one hundred. The Roman consul

Mutianus found 3,000 bronze statues at Athens, 3,000 at Rhodes, as many

at Olympia and at Delphi, although a great number had been previously

carried off from the last town.

In forming such statues, the alloy should be capable of flowing readily

into all the parts of the mould, however minute; it should be hard, in

order to resist accidental blows, be proof against the influence of the

weather, and be of such a nature as to acquire that greenish oxidized

coat upon the surface which is so much admired in the antique bronzes,

called _patina antiqua_. The chemical composition of the bronze alloy is

a matter therefore of the first moment. The brothers Keller, celebrated

founders in the time of Louis XIV., whose _chefs d’œuvre_ are well

known, directed their attention towards this point, to which too little

importance is attached at the present day. The statue of Desaix in the

Place Dauphine, and the column in the Place Vendôme are noted specimens

of most defective workmanship from mismanagement of the alloys of which

they are composed. On analyzing separately specimens taken from the

bas-reliefs of the pedestal of this column, from the shaft, and from the

capital, it was found that the first contained only six per cent. of

alloy, and 94 of copper, the second much less, and the third only 0·21.

It was therefore obvious that the founder, unskilful in the melting of

bronze, had gone on progressively refining his alloy, by the oxidizement

of the tin, till he had exhausted the copper, and that he had then

worked up the refuse scoriæ in the upper part of the column. The cannons

which the government furnished him for casting the monument consisted

of--

Copper 89·360

Tin 10·040

Lead 0·102

Silver, zinc, iron, and loss 0·498

-------

100·000

The moulding of the several bas-reliefs was so ill executed, that the

chiselers employed to repair the faults removed no less than 70 tons of

bronze, which was given them, besides 300,000 francs for their work. The

statues made by the Kellers at Versailles were found on chemical

analysis to consist of--

No. 1. No. 2. No. 3. The mean.

Copper 91·30 91·68 91·22 91·40

Tin 1·00 2·32 1·78 1·70

Zinc 6·09 4·93 5·57 5·53

Lead 1·61 1·07 1·43 1·37

------ ------ ------ ------

100·00 100·00 100·00 100·00

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