3. Acetic acid (Ph. L.), 1 pint; creasote, 5 dr.; mix. White.

4. Barbadoes tar, 1/4 oz.; burnt sugar and common salt, of each 1 oz.;

strong pickling vinegar, 3/4 pint; port or elder wine, 1/4 pint; digest as

before. Inferior to the preceding. Used to impart a smoky flavour to meat,

fish, &c., by brushing it over them, or adding a little to the brine in

which they are pickled.

=Essence of Worm'wood.= _Syn._ ESSENTIA AMARA, E. ABSINTHII, L. _Prep._ 1.

Extract of wormwood, 4 oz.; oil of wormwood, 1 oz.; rectified spirit, 1

pint; digest a week and filter. Tonic, stomachic, and vermifuge.--_Dose_,

10 drops to a teaspoonful.

2. (Van Mons.) Tincture of wormwood, 1 pint; salt of wormwood, 5 dr.;

extract of wormwood, 1 dr.; digest as before.--_Dose_, 1/2 to 1-1/2 fl.

dr.

=Essences, Fla''vouring.= _Syn._ CULINARY ESSENCES, SPICE E., ESSENCES FOR

THE TABLE, &c. Those used by cooks, confectioners, liqueurists, &c., are

all made by either dissolving 1 fl. oz. of the essential oil of the

particular substance in 1 pint of rectified spirit, or by digesting 4 to 6

oz. of the bruised spice, or 5 to 10 oz. of the dried herb, in a like

quantity (1 pint) of spirit. The first method is preferable, from being

the least troublesome, and yielding the finest product. They are commonly

labelled 'CONCENTRATED ESSENCE OF ----.' An inferior article, vended under

the names of 'ESSENCES OF CULINARY HERBS,' 'CULINARY TINCTURES,'

'TINCTURES FOR KITCHEN USE,' &c., are prepared from half the above

quantity of oil or spice, infused in a pint of proof spirit or British

brandy. The principal compounds of this class are the essences of

allspice, caraway, cardamoms, cassia, cayenne, celery seed, cinnamon,

cloves, coriander seed, fennel, garlic, ginger, lemon peel, mace,

marjoram, nutmegs, orange peel, peppermint, spearmint, sweet basil, and

the like. The whole of these are employed to flavour soups, gravies,

sweetmeats, pastry, wines, mulled wines, liqueurs, &c.

=Essences, Flower.= Those for which separate formulæ are not given in this

work may most of them be made from the essential oil of the flowers and

rectified spirit, as the last; or by digesting the flowers (crushed or

bruised), 3 to 5 lbs., in proof spirit, 2 galls., for a few days, and then

drawing over, by distillation, 1 gall. For the essences of those flowers

which are not strongly odorous, the spirit thus obtained is distilled from

a like quantity of flowers, a second, and a third time, or even oftener.

The essences of other organic substances, whose fragrant principles are

volatile, may be prepared in the same manner. A small quantity of some

other odorous essence is frequently added to the product, to enrich or

modify the fragrance. See FLOWERS and ESSENCES BY INFUSION.

=Essences, Fra'grant.= See FLOWER ESSENCES (_above_), ESSENTIA ODORATA,

PERFUMERY, &c.

=Essences, Fruit.= See ESSENCES OF APPLE, PINE-APPLE, JARGONELLE, &c.

=Essences by Infu'sion.= This term, among perfumers, is commonly applied

to those essences, eaux, and esprits, which are prepared by digesting the

ingredients in the spirit used as the vehicle for the aroma, in opposition

to those obtained by 'distillation,' or by 'contact,' or 'pressure.' Thus,

the ESSENCES OF AMBERGRIS, MUSK, and VANILLA, are of this class.

=Essences, Vi'nous.= _Syn._ ESSENTIA VINOSA, L. These are prepared in a

similar way to the wines (VINA) of the pharmacop[oe]ia, by using 8 times

the usual quantity of ingredients, and the very strongest sherry wine. 1

fl. dr., added to 7 fl. dr. of wine or water (properly the first only),

forms an extemporaneous imitation of the officinal VINA MEDICATA. Some of

the above are largely used in dispensing, and by travellers. See LIQUOR

and WINE.

=ESSENTIA BI'NA.= See COLOURING.

=Essentia, Odora'ta.= _Prep._ 1. Oil of lavender, 1 dr.; oils of cloves,

cassia, and bergamot, of each 1/2 dr.; neroli, 20 drops; essence royale, 2

fl. dr.; rectified spirit, 1/2 pint; mix.

2. (Redwood.) English oil of lavender, 48 drops; oil of cloves, 32 drops;

oil of orange peel, 16 drops; oil of bergamotte and sweet spirit of nitre,

of each 8 drops; oil of yellow sandal-wood, neroli, and otto of roses, of

each 2 drops; oil of cinnamon, 1 drop; rectified spirit, and essence of

ambergris and musk, of each 1 oz.; honey water, 8 oz.; mix. Used as a

perfume for the handkerchief, &c. The last form seems unnecessarily

complicated and minute.

=Essentia Odorif'era.= _Prep._ 1. Grain musk and balsam of Peru, of each

10 gr.; civet, 4 gr.; oil of cloves, 5 drops; oil of rhodium, 3 drops;

salt of tartar (dried by a dull-red heat and cooled), 1/2 dr.; rectified

spirit (strongest), 2-1/2 fl. oz.; macerate for 14 days, and pour off the

clear.

2. Oil of rhodium and balsam of Peru, of each 1/2 dr.; oil of cloves, 1

dr.; spirit of ammonia, 2 fl. dr.; essence of civet and vanilla, of each 2

fl. oz.; essence of musk, 5 fl. oz.; neroli, oils of lavender, verbena,

and cassia, of each 6 drops. As last. Both are very pleasant, durable, and

powerful perfumes for personal use.

=ESSENTIAL OIL.= See OIL (Volatile).

=ESSENTIAL SALT OF BARK.= See BARK and =Extract=.

=ESSENTIAL SALT OF LEMONS.= _Syn._ SALT OF LEMONS; SAL LIMONUM, L. The

preparation sold under this name is made by mixing cream of tartar

(bitartrate of potassa) with twice its weight of salt of sorrel

(quadroxalate of potassa), both in fine powder. It is used to remove fruit

stains, &c., from linen, by rubbing a little of it on the part moistened

with warm water. It is poisonous, if swallowed in quantity.

=ETCH'ING.= A species of engraving, in which the design is formed on the

plate by the action of an acid, or some other fluid, instead of being cut

out by the graver.

_Proc._ In the ORDINARY PROCESS OF ETCHING the plate is covered with

'etching ground' (an acid-resisting varnish), and the design is scratched

on the metal through the ground, by means of a pointed tool of steel

called the 'etching needle' or 'point.' A border of wax is then placed

round the plate, and the 'biting' fluid poured on, and allowed to remain

till the 'lights' or finest portions of the design are sufficiently

'bitten in,' The etching fluid is then poured off, the plate washed, and

the light parts 'stopped out' with Brunswick black or other varnish; the

solvent is again poured on, and allowed to remain until the finest portion

of the exposed lines are sufficiently deep, when the acid is again poured

off, and the whole process is repeated till the very darkest lines or

shadows are sufficiently 'bitten in,' The plate is then cleaned, and is

ready to be printed from. Occasionally the etched design receives a few

finishing touches with the 'graver.'

There are several varieties of etching, of which the following are the

principal:--ETCHING WITH A SOFT GROUND, when a coating of lard or tallow

is employed, and the design is drawn on a piece of paper, laid evenly on

the ground, by which means the fatty matter adheres to the paper, on the

parts pressed on by the point or pencil, and the copper beneath becomes

exposed, and is then acted on by the acid. The effect resembles that of

chalk or pencil drawings.--STIPPLING, or executing the design in dots

instead of lines.--AQUATINTA or AQUATINT, a mode of etching on copper for

producing an effect resembling a drawing in Indian ink. It is performed by

sifting powdered asphaltum or lac resin on the plate, previously slightly

greased, and, after shaking off the loose powder, gently heating it over a

chafing dish; on cooling, the lights are covered with turpentine varnish

coloured with lampblack, by means of a hair pencil, and a rim of wax being

placed round the plate, a mixture of 'aquafortis' and water is poured on

it, and allowed to remain for 5 or 6 minutes, when it is poured off, the

plate dried, and recourse had to the pencil as before. The process of

'stopping' and 'etching' is repeated again and again, until the darkest

shades are produced. Sometimes, instead of using asphaltum, an alcoholic

solution of shell-lac or gum mastic is poured over the plate, placed in a

slanting direction; this varnish forms a film, which, on drying, leaves

innumerable cracks or minute fissures through which the acid acts on the

plate. The fineness or coarseness of the grain depends entirely upon the

condition of the powdered asphaltum, or on the quantity of matter

dissolved in the spirit employed to form the ground.

The fluids employed for 'biting in' the designs vary considerably, almost

every artist having his own receipt. Aquafortis, more or less diluted, is,

however, generally employed for COPPER, and this, with the addition of

pyroligneous acid, for etching on STEEL; but any fluid that rapidly

dissolves the metal may be used for the purpose. The 'etching ground' may

be formed of any substance capable of resisting the action of the etching

fluid, and which is, at the same time, sufficiently soft to allow of the

free use of the needle or point, and sufficiently solid to prevent an

injury to the design during the 'scratching in,'

In ETCHING ON GLASS, the ground is laid on, and the design 'scratched in'

in the usual way, when liquid hydrofluoric acid is applied, or the glass

is exposed to the action of hydrofluoric acid gas. The former renders the

surface of the etching transparent, the latter opaque. A simple

modification of the process is to wet the design with sulphuric acid, and

then to sprinkle on some finely pulverised fluor spar (fluoride of

calcium), by which means hydrofluoric acid is set free and attacks the

glass. This method may be very easily applied to the graduation of glass

vessels, thermometer tubes, &c.

ETCHING ON GLASS BY ELECTRICITY. Planté ('Ann. Chem. Phys.' [5], xiii,

143-144). The author had previously drawn attention to the fact that when

an electric current is passed through saline solutions in glass vessels,

platinum wire serving as electrodes, the glass is immediately attacked,

and he therefore proposes the following method for etching on glass:

The surface of the glass to be engraved is coated with a concentrated

solution of potassium nitrate, and beneath the layer of liquid a platinum

wire, connected with one of the poles of a battery, is stretched across

the plate. With the other pole is connected another platinum wire, the

whole of which, except the point, is insulated; with this the designs are

drawn on the glass, which is engraved wherever the wire comes in contact

with it, flashes of light being emitted at the same time.

The depth of engraving depends on the rate at which the platinum wire

moves; the slower the rate the deeper the line.

A RAPID METHOD OF ETCHING ON IRON OR STEEL, capable of very general

application, is as follows:--"The metal is warmed until it is capable of

melting a piece of beeswax, or 'etching ground,' which is then carefully

rubbed over it, so as to form a thin and even coating; when cold, the

design is 'scratched in' in the common way; a little powdered iodine is

then sprinkled on the exposed parts, and at the same time a few drops of

water are added, and the two worked into a liquid paste with a camel-hair

pencil. The paste is then moved about over the intended etching, for a

period varying from one to five minutes, according to the depth of the

lines required to be produced. Afterwards the whole is removed, and

reapplied, &c., as with the usual etching fluids. The same etching-paste,

by being kept for a few days, again acquires the property of dissolving

iron, and may be used again and again; but independently of this, the

iodide of iron formed during the process, if rapidly evaporated to dryness

in a clean iron vessel by a moderate heat, and placed in stoppered

bottles, will sell for more than the original cost of the iodine. To

travellers and amateurs who amuse themselves with the delightful art of

etching, iodine, from its portability and convenience, will, doubtless,

prove invaluable. We have adopted it with considerable success, and have

found it especially useful in marking surgical instruments, razors, and

other edge tools. We published this method many years ago. Several parties

have since availed themselves of our suggestions and formulæ, but without

the slightest acknowledgment of the source from which they obtained them."

(A. J. Cooley.)

=Etching, Electro-.= This mode of etching, which is in many respects

superior to the ordinary mode, is based upon the destructive action of

certain 'anions' during 'electrolysis.'[281] If two plates of copper be

connected with the opposite ends of a voltaic battery, and placed in a

vessel containing very dilute sulphuric acid, the plate connected with the

copper of the battery will be attacked by the anion oxygen which is

released during the decomposition of the acid. This destructive action can

be localised at pleasure by covering certain parts of the plate with a

protecting stratum of varnish, ordinary 'etching ground' for instance. In

the practice of electro-etching, the drawing is 'scratched in' in the

usual way through an ordinary ground; a stout wire is then soldered to the

plate, and this, as well as the back of the plate, is coated with

sealing-wax varnish. Thus prepared, the plate is placed in a suitable

'decomposition cell' opposite a plate of somewhat similar size, and the

two are connected respectively with the copper and zinc of a 'Daniell's

cell,' or the silver and zinc of a 'Smee's cell.'[282] After about ten

minutes the plate is removed, washed, and dried; and when the 'fine work'

has been stopped out with Brunswick black, it is returned for another

space of ten minutes. By alternately exposing the plate to the action of

the decomposing fluid, and 'stopping out' parts of the work, the required

gradation in tints is obtained. The exact duration of the various

exposures, as well as their number, must, of course, be regulated by

circumstances. See ETCHING FLUIDS (_below_).

[Footnote 281: See ELECTROLYSIS and ELECTROTYPE, pages 428 and 429.]

[Footnote 282: See VOLTAIC ELECTRICITY.]

=Etching Fluids.= 1. (For COPPER.)--_a._ From 'aquafortis,' 2-1/2 fl. oz.;

water, 5 fl. oz.; mix.

_b._ To the last add of verdigris, 1 oz.; water, 2-1/2 fl. oz.; dissolve.

For light touches.

_c._ (EAU FORTE,--Callot and Piranesi.) Alum, sal-ammoniac, sea salt, and

verdigris, of each 4 oz.; vinegar (pyroligneous acid), 8 fl. oz.; water,

16 fl. oz.; mix, dissolve, boil for 1 or 2 minutes in a glazed or

stoneware vessel, cool, and decant the clear portion. Used as the last.

_d._ Water acidulated with sulphuric acid. Used in the process of

electro-etching.

2. (For STEEL.)--_a._ From iodine, 1 oz.; iron filings or wire, 1/2 dr.;

water, 4 fl. oz. It must be kept in a stoppered bottle, until required for

use.

_b._ From iodine, 3 dr.; iodide of potassium, 1 dr.; proof spirit, 1 fl.

oz.; water, 2 fl. oz. As the last.

_c._ (Mr Turrel.) Pyroligneous acid, 4 fl. oz.; alcohol (rectified

spirit), 1 fl. oz.; mix, and add of nitric acid or double aquafortis (sp.

gr. 1·28), 1 fl. oz.

_d._ From hydrochloric acid, 5 parts; water, 95 parts; mix, and add the

liquid to a solution of chlorate of potassa, 1 part, in water, 50 parts.

_e._ A solution of common salt. Used in the process of electro-etching.

=Etching Ground.= _Syn._ ETCHING VARNISH. _Prep._ 1. Beeswax, 5 parts;

linseed oil, 1 part; melted together.

2. (Callot's HARD VARNISH, FLORENTINE V., FLORENCE V.) From linseed oil

and mastic, equal parts, melted together.

3. (Callot's SOFT VARNISH.) From linseed oil, 4 oz.; gum benzoin and white

wax, of each 1/2 oz.; boil to two thirds.

4. (Lawrence.) White wax, 2 oz.; black pitch and Burgundy pitch, of each

1/2 oz.; melt, add by degrees, of powdered asphaltum, 2 oz.; and boil

together, until a piece, when thoroughly cold, will break by being bent

double 2 or 3 times between the fingers; next pour it into warm water,

make it into small balls, and place each of them in a piece of taffety for

use.

_Obs._ The preceding compositions are applied to the surface of the

plates, previously made sufficiently warm to melt them easily, their even

diffusion being promoted by dabbing them with a wad of cotton. Those that

are white are then generally blackened on the surface by skilfully passing

them over the smoky flame of one or more candles, by which the marks of

the etching point on the bright metal are rendered the more visible.

=E'THER.= _Syn._ OXIDE OF ETHYL. Described under ETHYL, OXIDE OF. Several

substances are known under the name of ethers besides the true ethers or

salts of ethyl, and are given below.

=Ether of Canthar'ides.= _Syn._ ÆTHER CANTHARIDALIS, L. _Prep._

([OE]ttinger.) From powdered cantharides, 1 part; ether, 2 parts; digested

together for 3 or 4 days, and the tincture expressed. Used as a vesicant,

&c.

=Ether, Chlo''ric.= This name was applied by Dr T. Thomson to the CHLORIDE

OF OLEFIANT GAS, or 'DUTCH LIQUID,' and afterwards, by Guthrie and

Silliman, to CHLOROFORM, which they took for an alcoholic solution of

chloride of olefiant gas. It now forms one of the synonyms of chloroform.

The medicinal 'CHLORIC ETHER' of the shops is a solution of chloroform, 1

part, in rectified spirit 8 parts; of which the _dose_ is 20 or 30 drops

in water, as an antispasmodic and anodyne. See CHLOROFORM.

=Ether, Chlorinet'ted.= Formed by the action of dry chlorine on pure

ether. When the action is long continued, a heavy, oily product

(BICHLORINETTED ETHER), smelling like fennel, is formed. By the still

further action of chlorine, aided by sunlight, a white, crystalline

substance (PENTACHLORINETTED ETHER), a compound resembling sesquichloride

of carbon, is obtained.

=Ether, Cu''preous.= _Syn._ TINCTURA CUPRI CHLORIDI ÆTHEREA, L. _Prep._

(Van Mons.) Sulphate of copper, 6 parts, and chloride of barium, 5 parts,

are triturated together, and the mixture digested in ether, 3 or 4 parts,

until all the chloride of copper is dissolved.--_Dose_, 2 to 5 drops; in

epilepsy, &c.

=Ether, Methy'lic.= _Syn._ OXIDE OF METHYL, WOOD-ETHER, METHYL-ETHER;

ÆTHER METHYLICUS, L. _Prep._ From wood spirit, 1 part; concentrated

sulphuric acid, 4 parts; mix in a retort, apply heat, pass the evolved gas

(methylic ether) through a little strong solution of potassa, and then

collect it over mercury. See METHYL.

=Ether, Spirits of Nitrous.= See SPIRITS.

=Ether, Washed.= _Syn._ ÆTHER LOTUS, L. Ordinary ether, agitated first

with 2 or 3 times its volume of distilled water, and a few grains of

carbonate of potassa, or a few drops of milk of lime; and after

decantation, again agitated with a like quantity of water only. Used for

inhalations. For other purposes the washed ether is afterwards digested on

chloride of calcium, to deprive it of retained water.

=E'THERIN.= _Syn._ CAMPHOR OF OIL OF WINE. A volatile, white, crystalline

substance, deposited by light oil of wine when left in a cold situation

for some time. It is isomeric with etherole, and received its name from

the assumption of its being the base of the ethereal compounds. According

to this hypothesis, ether is a hydrate of etherin. Etherin forms brilliant

prisms and plates; is tasteless; soluble in alcohol and ether; fuses at

230° Fahr., and boils at 500° Fahr.; and is a little lighter than water.

The crystals are purified by pressure between the folds of bibulous paper,

solution in ether, and evaporation.

=E'THEROLE.= The yellowish, oily liquid, forming the residual portion of

light oil of wine, after it has deposited its etherin. It is lighter than

water; is freely soluble in both alcohol and ether; and has a rather high

boiling-point. See ETHERIN and OIL OF WINE.

=ETHION'IC AC'ID.= _Prep._ An alcoholic solution of the crystals of

sulphate of carbyle is diluted with water, the whole neutralised with

carbonate of baryta, the filtered liquid evaporated by a very gentle heat

to a small bulk, and a large quantity of alcohol added; the precipitate

(ethionate of baryta) is treated (cautiously) with dilute sulphuric acid

(avoiding excess), by which the baryta is withdrawn, and ethionic acid

left in solution.

_Prop., &c._ Ethionic acid closely resembles sulphovinic acid. It is

decomposed by heat. Its salts (ethionates), however, differ completely

from the sulphovinates. They are all soluble in water, and are said to be

anhydrous. The ethionates of ammonia, potassa, and soda crystallise

readily; those of lead, baryta, lime, and the other earths are

uncrystallisable. See ISETHIONIC ACID, and _below_.

=ETHION'IC ANHY'DRIDE.= _Prep._ Pure and dry olefiant gas is passed over

anhydrous sulphuric acid ('sulphuric anhydride') contained in a U-shaped

tube.

_Prop., &c._ When thus produced, it is in white, milky crystals, which

speedily deliquesce in the air, giving rise to ethionic acid. It is

similar in appearance, and probably identical with, 'sulphate of carbyle,'

which results from the absorption of the vapour of anhydrous sulphuric

acid by absolute alcohol.

=E'THIOPS.= _Syn._ ÆTHIOPS, L. A name given by the older chemists to

several black powders on account of their colour, and still occasionally

employed in medical works.

=Ethiops, Graphi'tic.= _Syn._ ETHIOPS OF PLUMBAGO; ÆTHIOPS GRAPHITICUS, L.

From plumbago, 2 parts; quicksilver, 1 part; triturated together until the

globules disappear.--_Dose_, 5 to 10 gr.; in herpes, and some other

obstinate skin diseases.

=Ethiops, Martial.= Black oxide of iron, prepared by keeping iron filings

under water, and occasionally shaking them. It is washed with water, dried

as quickly as possible, and preserved from the air, to prevent further

oxidation. Formerly much esteemed as a tonic.

=Ethiops, Min'eral.= _Syn._ ETHIOPS MINERAL; ÆTHIOPS MINERALIS, HYDRARGYRI

SULPHURETUM CUM SULPHURE, L. Black sulphuret of mercury, with excess of

sulphur.

(Tyson's.) Oxide of mercury (prepared by decomposing calomel with an

equivalent proportion of liquor of potassa to which a little liquor of

ammonia has been added) and flowers of sulphur, equal parts, triturated

together. This is recommended as an efficient substitute for the old and

uncertain preparation commonly sold under the name of _Ethiops mineral_.

It is, however, of more than double the usual strength, and should

therefore be taken in proportionate doses. See MERCURY (Sulphide).

=Ethiops, Veg'etable.= _Syn._ ÆTHIOPS VEGETABILIS, PULVUS QUERCÛS MARINÆ,

L. Bladder wrack (_Fucus vesiculosus_), burned in a close vessel till it

becomes black and friable. Used in bronchocele, scrofula, &c. Like burnt

sponge, it owes its virtues to the presence of a very minute quantity of

iodine.--_Dose_, 20 gr. to 1 dr., or more, made into an electuary with

honey or sugar.

=E'THYL.= C_{2}H_{5}. _Syn._ ETHYLE. The hydrocarbon assumed to be the

radical of the ether-compounds (ethyl-series). A body containing carbon

and hydrogen in the proportions indicated by the formula of ethyl,

2(C_{2}H_{5}), has been obtained by exposing dry iodide of ethyl in sealed

tubes for several hours to the action of finely divided zinc, at a

temperature of from 320° to 338° Fahr. In this reaction the iodine of the

iodide of ethyl combines with the zinc, and the hydrocarbon supposed to be

ethyl is set free. On opening the sealed tubes and allowing the gas (which

is a mixture of the 'ethyl' and certain secondary products) to pass into a

freezing mixture, the temperature of which is kept below -9° Fahr., the

'ethyl' condenses to a colourless, mobile liquid. Hitherto no compound

ether has been produced from the 'ethyl' thus prepared.

According to the beautiful theory of Liebig, ethyl is a 'salt-basyle,'

forming 'haloid salts' with chlorine, iodine, and bromine; its oxide is

ether, and the hydrate of this oxide alcohol. The compound ethers may be

compared with ordinary salts in which the metal is replaced by the radical

ethyl.

=Ethyl, Oxide of.= (C_{2}H_{5})_{2}O. _Syn._ ETHER, SULPHURIC ETHER, ÆTHER

(B. P.), ÆTHER SULPHURICUS (PH. E. D. & U. S.), Æ. RECTIFICATUS, Æ.

VITRIOLICUS, Æ. SPIRITUS VITRIOLI DULOIS, L. A colourless, highly

volatile, fragrant, inflammable liquid, obtained by distilling a mixture

of sulphuric acid and alcohol. It was not known before the 13th century.

_Prep._ There are two methods employed for the preparation of ether. The

one is by mixing the whole of the ingredients at once, and immediately

subjecting them to distillation at a proper temperature; the other is by

adding the alcohol in a slender streamlet to the acid, previously heated

to the etherifying point. The former, though less economical, is the one

more generally employed.

1. Rectified spirit, 3 lbs.; sulphuric acid, 2 lbs.; carbonate of potassa

(previously ignited), 1 oz.; pour 2 lbs. of the spirit into a glass

retort, add the acid, and place the vessel on a sand bath, so that the

liquor may boil as quickly as possible, and the ether, as it forms, pass

over into a well-cooled receiver; continue the distillation until a

heavier fluid begins to pass over, then lower the heat, add the remainder

of the spirit, and distil as before; mix the distilled liquors together,

pour off the supernatant portion, add the carbonate of potassa, and

agitate occasionally for one hour; finally, distil the ether from a large

retort, and keep it in a well-stoppered bottle. Sp. gr. ·750.

2. The strongest oil of vitriol, 3 parts, are mixed with alcohol, q. s.

(about 2 parts at ·830) to reduce its sp. gr. to 1·780; an object which

may be easily obtained by distilling off some of the ether if required.

The still or retort is then connected with a vessel full of alcohol, of at

least 90%, by means of a small syphon tube, furnished with a stop-cock;

the longer limb of which should be of glass, and so arranged that it just

dips into the mixture of acid and alcohol. Heat is next applied, and the

contents of the still raised to the boiling-point as rapidly as possible,

and as soon as full ebullition commences the stop-cock of the syphon is

cautiously turned, so as to allow the alcohol to flow down in such a

manner as to keep the boiling liquid exactly at the same level; or, in

other words, to supply a quantity of alcohol exactly equal to that of the

liquid which distils over. By careful manipulation the whole of the

alcohol which enters the retort passes over as ether and water, and this

decomposition proceeds for some time, and would continue for an unlimited

period did not the sulphuric acid ultimately become too weak to form

ether, from the gradual absorption of the superfluous water contained in

the alcohol. Were it convenient or practicable to use absolute alcohol, a

given weight of sulphuric acid of the proper strength, would maintain the

power of producing ether for an indefinite period. In practice, the

quantity of alcohol that may thus be etherified is twice or thrice as much

as by the common process, while neither sulphurous acid, sulphovinic acid,

nor sweet oil of wine is generated, and the residual liquid of the

distillation continues limpid, and has only a pale-brown colour. This is

termed the 'continuous,' or 'Boullay's' method. (This process is similar

to that given in the B. P.)

3. Alcohol of 90%, five parts are mixed with oil of vitriol, 9 parts, in a

vessel of copper or iron immersed in cold water; the mixture is next

introduced into a still or retort, and raised to a state of ebullition as

rapidly as possible, as before. A fresh quantity of alcohol, equal in bulk

to the liquid distilled over, is then added to the liquid in the still,

and distillation again had recourse to. As much concentrated alcoholic

solution of potassa as will give it a perceptible alkaline reaction is

next added to distilled liquor, which is then rectified by the heat of a

water bath, as long as the ether which distils over has the sp. gr. ·720

to ·725 at 80° Fahr. Instead of the potassa, a little milk of lime may be

used, along with its own bulk of water. By allowing the product to stand

for some days over chloride of calcium or quicklime, and again rectifying

it along with one of these substances, perfectly pure ether may be

obtained.

_Obs._ The mixture of alcohol with sulphuric acid requires some caution.

It is best done by introducing the alcohol into a suitable vessel, and

imparting to it a rapid whirling motion, by which a considerable conical

cavity is formed in the centre, and into which the acid may be gradually

poured with perfect safety. The mixed fluids should be brought to a state

of rapid ebullition, as quickly as possible, as without this precaution

much of the alcohol distils over before the liquor acquires the proper

temperature for etherification. On the small scale, a tubulated retort,

connected with a Liebig's condensing tube, and two globular receivers

surrounded with a freezing mixture, or ice-cold water, may be employed as

the distillatory apparatus. The second receiver should be connected with

the first one by means of a bent glass tube, reaching nearly to the bottom

of the former; and the whole of the joints should be securely luted, as

soon as the expanded air has been allowed to escape. We have employed the

following convenient little apparatus for the preparation of small

quantities of ether, and it will be found very suitable for the

distillation of most other highly volatile liquids, and particularly for

boiling mixtures of alcohol and organic acids. By connecting the neck of a

flask or digester containing volatile fluids with the lower instead of the

upper end of the refrigerator, ebullition may be carried on without loss,

as the vapour will be condensed, and run back into the vessel from which

it has distilled.

[Illustration:

_a._ Condenser tube.

_b, c_ Glass tube.

_d._ Funnel by which cold water runs in from the water bottle _h_.

_e._ Pipe by which water escapes through _f_ into the bottle _g_.

_i._ Retort.

_k._ Adapter, connecting the retort with the condenser.

_l._ Adapter, connecting the condenser with the bottles _t, t_.

_A._ Wooden tressel, with movable arms _n, o_, for supporting and

adjusting the heights of the condenser.

_B._ Wooden stool for supporting the water bottle.

_q._ Furnace.

_r._ Support for the furnace.

_p._ Gutter for carrying off water that overflows the funnel _d_,

and preventing its escape along the pipe _c_.

_s._ Leg of syphon connected with bottle containing alcohol.

_t, t._ Glass globes, placed in the basins _v, v_, and surrounded

with pounded ice or ice-cold water.

_w._ Safety tube, containing a little mercury at _x_.]

For the rectification of ether, a water bath is employed along with the

above simple refrigerator, and the receivers surrounded by ice or a

freezing mixture.

_Chem. comp., &c._ Ether is generally regarded as the oxide of ethyl, and

alcohol as the hydrate of this base. This view is borne out by analysis,

which proves that ether differs from alcohol by the elements of water.

Recent experiments have also shown that the relation existing between the

two compounds is--if alcohol be expressed by the formula C_{2}H_{6}O, the

true formula of ether will be (C_{2}H_{5})_{2}O. We cannot describe these

experiments here, but we may remark that ether cannot be made to combine

with water directly, nor can alcohol be converted into ether by the

abstraction of water, pure and simple, without the aid of other

substances.

The compound ethers may be compared to ordinary salts in which the metal

is replaced by a radical termed ethyl, having the formula C_{2}H_{5}. This

view is, of course, in accordance with the theory which regards ether as

the oxide of ethyl.

According to theory, 1 equivalent, or 46 parts of absolute alcohol, should

produce 1 eq., or 37 parts, of pure ether; but in practice, the greatest

product obtained by operating according to Boullay's method, which

produces more ether than any other, does not exceed 33-1/2 parts for the

preceding quantity of alcohol, or 71·5%. A mixture of 9 parts of oil of

vitriol, and 5 parts of alcohol of 90%, ceases to produce ether after 31

parts of such alcohol have been added.

The most economical method of etherification is that known as the

continuous ether process, or the process of Boullay. When this is adopted,

the retort or flask should be fitted with a sound cork, perforated by an

aperture to receive a thermometer, and the application of the heat, and

the flow of alcohol, should be so managed, that a temperature of 300°

Fahr. and a state of rapid and violent ebullition (points of essential

importance) are maintained.

_Prop., Uses, &c._ Pure ether is a colourless, transparent, and very

limpid fluid, having a penetrating and agreeable smell, and a burning,

sweetish taste; its evaporation produces the sensation of extreme cold;

when prevented, a sensation of heat is experienced. Its specific gravity

varies between ·712 and ·724. If it contains water it begins to

crystallise in brilliant white plates when cooled to -24° Fahr., and

become a white crystalline mass at -46° or -47° Fahr.; but if absolutely

pure, ether cannot be solidified by any degree of cold that can be

produced, it remaining fluid when placed in contact with solid carbonic

acid, at a temperature of about -148° Fahr. Boils at 96° or 97° Fahr.; is

very combustible; is soluble in about 10 parts of distilled water, and

mixes with alcohol in all proportions. It abstracts corrosive sublimate,

terchloride of gold, sesquichloride of iron, and many of the alkaloids,

from their watery solutions, and is hence invaluable in analysis and

pharmacy. It readily dissolves the volatile and fixed oils, and most fatty

matters, as well as sulphur and phosphorus in small quantities. By

exposure to light and air it absorbs oxygen, and water and acetic acid are

gradually formed. It is decomposed by exposure to a high temperature. Its

evaporation occasions intense cold. The greatest degree of cold yet

produced (-166° Fahr.) has resulted from the admixture of ether with solid

carbonic acid. Ether is powerfully stimulant, narcotic, and antispasmodic,

and externally refrigerant, if allowed to evaporate, or stimulant and

counter-irritant if its evaporation is prevented, and is used in various

diseases. Applied to the forehead by means of the fingers or a strip of

linen, it generally relieves simple cases of nervous headache. In

_pharmacy_ it is largely employed in the preparations of tinctures

alkaloids, spirits, &c.; and in _chemistry_ is invaluable in organic

analyses. Its principal commercial application is as a solvent for

pyroxyline, in the manufacture of collodion. It is also employed as a

solvent of resins, india rubber, &c., in the preparation of varnishes, and

for several other useful purposes.--_Dose_, 20 drops to 2 fl. dr.; in

water or wine. Excessive doses of ether produce intoxication resembling

that from alcohol, and require similar antidotes. Sulphuric ether is said

to be taken largely in the north of Ireland as a stimulant, particularly

in Antrim. Shortly before the discovery of chloroform, it was found that

when the vapour of ether was inhaled it gradually produced insensibility

to pain. It was therefore employed as an anæsthetic in surgical

operations. Having been found less efficient than chloroform, and more

troublesome to administer, its use for this purpose has been abandoned.

_Tests._ Ether may be recognised by its volatility, odour, taste, sparing

solubility in water, admixture with alcohol in all proportions, great

inflammability (burning with a yellowish-white flame), and its power of

dissolving fats and resins. Its further identification can only be

effected by ultimate analysis.

_Pur._ The ether of the shops generally contains alcohol, water, or acetic

acid, and sometimes all of them. Its usual specific gravity fluctuates

between ·733 and ·765. Exposed to the air, it volatises entirely. It turns

litmus paper red; sometimes very slightly, and occasionally even not at

all. 1/2 fl. oz. mixes completely with 1/2 pint of water. Pure ether

should, however, be neutral to test-paper, although seldom so. When shaken

in a minim measure with half its volume of concentrated solution of

chloride of calcium, its volume should not lessen. 10 fluid ounces of

water should only dissolve 1 fluid ounce of ether, and remain transparent.

[Illustration]

_Preserv._ Ether rapidly evaporates at common temperatures when kept in

corked bottles, and even in bottles secured with ground-glass stoppers and

tightly tied over with bladder and leather; it also becomes sour by age.

To prevent this waste, the stoppers should fit accurately, and the bottles

should be placed in as cool a situation as possible. Bottles furnished

with ground-glass caps, as well as stoppers, are frequently employed. (See

_engr._) Dewar's 'ether phial' is formed on a similar principle. We have

seen bottles of ether accurately stoppered, tied over with bladder, and

thickly coated with wax, which have yet become quite empty by a voyage to

the tropics, though they still appeared to be as closely secured as when

they were first filled.

_Caution._ The vapour of ether is very inflammable, and when mixed with

atmospheric air, it forms a violently explosive mixture. The density of

this vapour is 2·586, that of air being 1; hence it rapidly sinks, and

frequently accumulates in the lower parts of buildings, especially cellars

which are badly ventilated, in the same way as water does. The only remedy

is thorough ventilation. Many serious accidents have arisen from this

cause, for no sooner is a light carried into an apartment where such

vapour is present than an explosion takes place.

=Ethyl, Acetate of.= C_{2}H_{5}C_{2}H_{3}O_{2} _Syn._ ACETATE OF OXIDE OF

ETHYL, ACETIC ETHER, PYROLIGNEOUS ETHER; ÆTHER ACETICUS, L. A compound

discovered by the Count de Lauraguais in 1759.

_Prep._ 1. Acetate of potassa, 3 parts (or an equiv. quant. of acetate of

soda), alcohol (85%), 3 parts, oil of vitriol (strongest), 2 parts, are

mixed together and distilled, by the heat of a sand bath, from a glass or

earthenware retort into a well-cooled receiver; the distillate is agitated

with a little water to remove undecomposed alcohol, and then digested

first with a little chalk to remove acidity, and afterwards with fused

chloride of calcium, to absorb water; it is, lastly, rectified by a gentle

heat.

2. Rectified spirit (sp. gr. ·84), 50 parts, acetic acid (sp. gr. 1·075),

33 parts, are mixed together, and oil of vitriol (strongest), 10 parts,

added; the distillation is continued until 65 parts have passed over, and

the distillate, after digestion for some hours on a little dry carbonate

of potassium, is rectified as before, the first 50 parts only being kept

for use.

_Prop., &c._ Acetic ether is colourless, and bears a considerable

resemblance to ordinary ether, but it has a much more agreeable and

refreshing odour. It boils at 165° Fahr.; has a sp. gr. of ·89 at 60°

Fahr., dissolves in about 7 parts of water; and mixes in all proportions

with alcohol and ether. It is decomposed by alkalies and the strong acids.

Acetic ether is diaphoretic, stimulant, antispasmodic, and

narcotic.--_Dose_, 1/2 to 2 fl. dr.; in similar cases to those in which

sulphuric ether is employed, and especially in nervous and putrid fevers,

spasmodic vomitings, and diseases of the bowels and stomach, arising from

debility, and not of an inflammatory character. Its principal consumption

is in the manufacture of British brandy.

=Ethyl, Benzoate of.= C_{2}H_{5}C_{7}H_{5}O_{2}. _Syn._ BENZOIC ETHER,

BENZOATE OF ETHER, B. OF OXIDE OF ETHYL; ÆTHER BENZOICUS, L. _Prep._

Alcohol (sp. gr. ·830), 4 parts; benzoic acid (cryst.), 2 parts;

concentrated hydrochloric acid, 1 part, are distilled together; as soon as

the product turns milky when mixed with water, the receiver is changed,

and the liquid that distills over collected; to this liquid water is

added, and the supernatant ether is decanted, and boiled with water, and a

little oxide of lead (to separate benzoic acid); it is, lastly, freed from

water by allowing it to stand over chloride of calcium.

_Prop., &c._ A colourless oily liquid, slightly heavier than water, and

possessing an aromatic odour and taste. It boils at 410° Fahr., and is

miscible with alcohol and ether.

=Ethyl, Bromide of.= C_{2}H_{5}Br. _Syn._ ÆTHER HYDROBROMICUS, L. A

volatile, ethereal liquid, discovered by Serullas.

_Prep._ Bromine, 8 parts; alcohol, 32 parts; dissolve, place the mixture

in a retort, add of phosphorus, 1 part, and distil by a gentle heat as

soon as the liquid becomes cold. The ether is separated from the

distillate by the addition of water.

_Prop., &c._ A very volatile liquid, with a penetrating taste and smell;

boiling at 105° Fahr., and heavier than water.

=Ethyl, Bu'tyrate of.= C_{2}H_{5}C_{4}H_{7}O_{2}. _Syn._ BUTYRIC ETHER,

PINE-APPLE OIL; ÆTHER BUTYRICUS, L. _Prep._ By passing hydrochloric acid

gas into an alcoholic solution of butyric acid, and purifying the product

from free acid.

Commercially, from crude butyric acid saponified with caustic potassa or

baryta, and the resulting soap distilled along with alcohol and oil of

vitriol.

_Uses._ Crude butyric ether forms the 'pine-apple oil' of commerce, and

when largely diluted with rectified spirit, the 'pine-apple essence' so

much employed as a flavouring substance by confectioners, liqueuristes,

&c. It imparts a delicious flavour to sweetmeats, rum, arrack, punch, &c.

The Germans add it to common rum, to form the flavouring for their

'pine-apple ale.'

=Ethyl, Carbonate of.= (C_{2}H_{5})_{2}CO_{3}. _Syn._ CARBONIC ETHER,

CARBONATE OF OXIDE OF ETHYL; ÆTHER CARBONICUS, L. _Prep._ Fragments of

potassium are added to oxalic ether, gently warmed, as long as bubbles of

gas are formed; the excess of metal is removed from the semi-solid mass,

some water added, and the whole distilled. The carbonic ether floats on

the surface of the liquid in the receiver, and is collected, dried by

contact with chloride of calcium, and rectified along with some potassium

or sodium, till it ceases to yield acetate of potassa when acted on by

caustic potassa.

_Prop., &c._ Colourless, limpid, and aromatic; tastes pungent and burning;

boils at 259° to 260° Fahr. It greatly resembles oxalic ether. It is

decomposed by alkalies.

=Ethyl, Chlo'ride of.= C_{2}H_{5}Cl. _Syn._ LIGHT HYDROCHLORIC E.,

CHLORIDE OF ETHYL; ÆTHER HYDROCHLORICUS, L. A highly volatile compound,

formed of ethyl and chlorine.

_Prep._ Rectified spirit of wine is saturated with dry hydrochloric acid

gas in the cold, and the product is distilled in a retort connected with a

Wolfe's apparatus, the first bottle of which should be two thirds filled

with tepid water (70° to 75° Fahr.), and the remainder surrounded with a

mixture of ice and salt. To render it perfectly anhydrous, it must be

digested on a few fragments of fused chloride of calcium.

A mixture of oil of vitriol, 3 parts, and alcohol, 2 parts, is poured upon

common salt (dried), 4 parts; and the whole distilled as before.

_Prop., &c._ This ether has a sweetish taste; is soluble in about 15 parts

of water, and miscible in all proportions with alcohol; boils at 54°

Fahr.; burns with a flame edged with green; is neutral to test paper; and

does not affect a solution of nitrate of silver. Sp. gr. ·921, at 32°

Fahr.--_Dose_, 10 to 30 drops, as an antispasmodic and a powerful

diffusible stimulant. Owing to its extreme volatility it can only be taken

dissolved in spirit.

=Ethyl, Cy'anide of.= C_{2}H_{5}CN. _Syn._ ÆTHER HYDROCYANICUS. L. _Prep._

Cyanide of potassium and sulphovinate of baryta, equal parts, are mixed

and distilled in a glass retort by a moderate heat. The product separates

into two strata; the lighter one is impure hydrocyanic ether; this is

decanted and agitated with 4 or 5 times its bulk of water at 120° to 140°

Fahr., and the operation is repeated with about 2 parts of water; the

ether is again decanted, and placed in contact with chloride of calcium

for 24 hours, and then rectified.

_Prop., &c._ It boils at 190° Fahr. Sp. gr. ·788. In its therapeutical

effects it resembles hydrocyanic acid, but is less active. Its odour is,

however, more penetrating and offensive.--_Dose_, 2 to 6 drops, in

mucilage or emulsion; in obstinate or convulsive coughs, gastrodynia,

hysterical affections, &c.

=Ethyl, Cy'anate of.= C_{2}H_{5}CNO _Syn._ CYANIC ETHER, CYANATE OF OXIDE

OF ETHYL. _Prep._ By distilling a dry mixture of cyanate of potassa and

sulphovinate of potassa in nearly equivalent proportions. A mixture of

cyanic and cyanuric ethers passes over into the receiver. By distilling

this mixture the two are readily separated; that which passes over by the

heat of a water bath being the first, and the residuum in the retort the

second.

_Prop., &c._ An ethereal, very mobile liquid, boiling at 140° Fahr.

=Ethyl, Cyan'urate of.= (C_{2}H_{5})_{3}C_{3}N_{3}O_{3}. _Syn._ CYANURATE

OF OXIDE OF ETHYL. _Prep._ See CYANIC ETHER.

_Prop., &c._ Tasteless, inodorous, colourless, transparent, needles and

prisms; fusing at 185° Fahr.

=Ethyl, I'odide of.= C_{2}H_{5}I. _Syn._ ÆTHER HYDRIODICUS, L. _Prep._

Phosphorous, 4 parts, alcohol (sp. gr. ·84), 70 parts, and iodine, 100

parts, are gradually and cautiously mixed together, and distilled.

_Prop., &c._ A colourless liquid, possessing a strong ethereal odour, and

boiling at 158° Fahr.; sp. gr. 1·92. It is reddened and decomposed by

exposure to air and light.

=Ether, Methy'lic.= _Syn._ OXIDE OF METHYL, WOOD-ETHER, METHYL-ETHYL. See

METHYL.

=Ether, Muriatic (Heavy).= _Syn._ ÆTHER MURIATICUS PONDEROSUS, L. _Prep._

Alcohol, of 80 to 85%, is saturated, in the cold, with chlorine gas, water

is next added, and the oily fluid that separates collected and washed with

water, as long as any of it is dissolved.

_Prop., &c._ Heavy muriatic ether is a volatile, oily, colourless liquid,

boiling at about 245° Fahr., and heavier than water. Its precise

constitution is undetermined. This ether enters into the composition of

the SPIRITUS MURIATICO-ETHEREUS, a remedy occasionally used on the

Continent.

=Ethyl, Nitrate of.= C_{2}H_{5}NO_{3}. _Syn._ NITRIC ETHER, NITRATE OF

OXIDE OF ETHYL; ÆTHER NITRICUS, L.

_Prep._ Nitric acid (sp. gr. about 1·375), 50 parts; nitrate of urea, a

little (say 2 or 3 parts); dissolve, add alcohol, 50 parts, and distil

with the usual precautions, until 7-8ths of the whole (of the liquid

portion) have passed over; agitate the distillate with a little water to

separate the ether, and preserve the heavier portion.

_Prop., &c._ Nitric ether possesses an agreeable sweetish taste and odour;

it is insoluble in water; the alcoholic (but not the aqueous) solution of

potassa decomposes it rapidly; sp. gr. 1·112. Its vapour is very apt to

explode when strongly heated, and therefore a small quantity only should

be prepared at a time.

=Ethyl, Nitrite.= C_{2}H_{5}NO_{2}. _Syn._ NITRIC ETHER, HYPONITROUS

ETHER, NITRITE OF ETHER, NITRITE OF OXIDE OF ETHYL, HYPONITRITE OF E.;

ÆTHER NITROSUS, Æ. HYPONITROSUS, L. This is a compound, of which 'sweet

spirit of nitre' is an impure alcoholic solution.

_Prep._ 1. Starch (potato farina), 1 part; nitric acid (sp. gr. 1·30), 10

parts; mix in a capacious retort, connected with a wide tube, 2 or 3 feet

long, bent at right angles, and terminating near the bottom of a

two-necked bottle, containing a mixture of alcohol (of 85%), 2 parts, and

water, 1 part, and surrounded with a freezing mixture, pounded ice, or

very cold water; the other neck of the bottle being connected by a long

glass tube with a good refrigerator or condenser. All elevation of

temperature must be avoided. The heat of a water bath only must be

cautiously applied to the retort. The gas liberated passes into the

alcohol, causing the ether to distil in a gentle stream. The tube

connecting the retort and bottle must be cooled by means of rag or moist

paper, kept wetted with ice-cold water; as, if the temperature of the tube

and the alcohol rises only a little, the latter becomes spontaneously hot,

and boils violently, by which the product is vitiated. This process is

very productive and economical, and yields pure nitrous ether.

2. A mixture of oil of vitriol, 8 parts, and alcohol, 9 parts, is poured

upon crystallised nitrate of ammonia, 11 parts, contained in any suitable

distillatory vessel connected with a well-cooled receiver. Nitrous ether

gradually distils over on the application of a gentle heat. An admirable

process, but more expensive than the preceding. Even a common fire may be

employed without danger, as the liberation of the ether proceeds

gradually, and not almost instantaneously, as in operating in the usual

way. Sulphate of ammonia is left in the retort. The product is scarcely

inferior to that of the last formula.

3. Rectified spirit, 46 fl. oz.; pure nitric acid (sp. gr. 1·500), 7 fl.

oz.; put 15 fl. oz. of the spirit, with a little clean sand, into a quart

matrass, fitted with a cork, and a safety tube reaching to within an inch

of the spirit, and a second tube leading to a refrigeratory. Fill the

safety tube with pure nitric acid, then add through it, gradually and

cautiously, 3-1/2 fl. oz. of the acid. When the violent action that ensues

is nearly over, gradually add the remaining portion of the acid, 1/2 fl.

oz. at a time, and at intervals. Agitate the ether that distils over,

first with a little milk of lime, till it ceases to redden litmus paper,

and then with half its volume of concentrated solution of chloride of

calcium. The pure hyponitrous ether thus obtained should have a density of

·899.

4. (Mr John Williams.) Nitrite of ethyl is best made by passing nitrous

acid gas into alcohol.

The nitrous acid gas is prepared by acting upon such bodies as starch,

copper, mercury, or arsenious acid with nitric acid. The alcohol is

generally recommended in the text-books to be diluted with half its bulk

of water; this, however, I consider a decided mistake. The alcohol should

be as concentrated as possible, even absolute alcohol is preferable. The

main points to be attended to are that the current of nitrous acid gas

should be slow and steady, so as to give time for the reaction to proceed

properly, and that the vessel containing the alcohol should be kept as

cool as possible; in this way much of the production of bye-products will

be avoided, and the gas can be passed through the alcohol, as long as it

continues to be absorbed.

The resulting liquid is anything but pure; it contains much nitrite of

ethyl, some aldehyde, acid--it is even stated to contain malic acid. In

fact it is well known that the reaction between the nitrous acid, and such

products as alcohol, however pure, is not sharp, but is always accompanied

by secondary products.

From the crude alcoholic solution obtained by the method I have described,

the pure nitrite of ethyl can be obtained without difficulty. Nitrite of

ethyl is an extremely volatile liquid; it boils at about 61° F., whereas

aldehyde boils at 90° F., and alcohol at 180° F. Taking advantage of this

fact, we are enabled to separate it from the crude liquid by distillation.

Some precautions are, however, necessary, to ensure the purity of the

product. The flask containing the crude product is placed in a water bath,

and connected by bent tubes with several other flasks and bottles. The

first tube should be passed into a small empty flask, this will condense

most of the alcohol which may pass over during the operation. Then a

second bent tube passes into a second flask containing a little water;

this condenses any alcohol which may not have been stopped in the first

flask, together with free acid, and nearly all the aldehyde.

From this wash bottle a third tube proceeds into a somewhat shallow flask,

containing a strong solution of caustic potash; the gas, however, is not

allowed to pass through this alkaline liquid, but simply over the surface.

In this way the last portion of the aldehyde is absorbed, and the potash

solution gradually assumes an amber colour. From this vessel, the gas (for

such at the ordinary temperature of the laboratory, the nitrite of ethyl

is--in very cold weather it would be necessary to gently warm the

different flasks) is passed through a tube charged with anhydrous chloride

of calcium to absorb moisture, and the pure and dry nitrite of ethyl thus

produced, finally passes into alcohol, which readily absorbs it.

It is only necessary to note the weight of the alcohol used for absorbing

the gas, and its weight at the end of the operation, to know the strength

or per-centage of nitrite of ethyl which must be in solution. Thus, if 9

oz. of alcohol becomes 10 oz., it is evident we have a solution of 10 per

cent.; if it becomes 12 oz., then the strength must be 25 per cent., and

so on. Ordinary spirits will answer for condensing the nitrite of ethyl,

but it is better to use absolute alcohol, as it is very desirable to avoid

the presence of water in any form. The solutions made with weaker spirit

soon turn acid; those made with absolute alcohol, on the other hand, keep

a long time. It is very true the very strong solutions of 50 and 25 per

cent. show traces of acidity when tested with moistened litmus paper, but

the 10 per cent. solution is quite neutral.[283]

[Footnote 283: The object of Mr Williams' paper, which is published in the

'Pharmaceutical Journal' for Dec. 8th, 1877, is to give instructions for

the preparation of a pure nitrite of ethyl, which when mixed with alcohol

in definite proportions, shall supersede the variable compound sold under

the name of "Sweet Spirits of Nitre."]

One point I have not mentioned; it is that the distillation must be

conducted at the very lowest possible temperature; in fact, the water in

the water-bath should only be kept gently warm, and the process should be

continued only so long as the conducting tubes feel cool to the touch;

when they become warm the distillation should be discontinued. By passing

the gas into a tube in a freezing mixture, instead of into alcohol, the

pure nitrite of ethyl is readily obtained in a liquid form; it is,

however, necessary to seal the tube, otherwise the very volatile liquid

would soon be lost.

_Prop., &c._ Pure nitrous ether has a pale-yellow colour, an agreeable

odour of apples, and boils at 62° Fahr.; sp. gr. ·947 at 60° Fahr.

Commercial nitrous ether contains aldehyde, boils at 70° Fahr., has a more

or less suffocating odour combined with that of the pure ether, has a sp.

gr. of ·886 at 40° Fahr., and turns brown when mixed with alcoholic

solution of potassa, while the latter remains unaltered. It also acidifies

by age, whilst pure nitrous ether remains neutral. They are both very

inflammable, and burn with a white flame. Ordinary nitrous ether dissolves

in about 48 parts of water, and mixes in all proportions with alcohol and

sulphuric ether.

Nitrous ether is refrigerant, diaphoretic, and diuretic, but is seldom

employed alone, though, when largely diluted with alcohol (sweet spirits

of nitric, spirit of nitric ether), it is a common remedy in several

diseases. It is also used to flavour malt spirit, in imitation of brandy

(British brandy), although for this purpose it is vastly inferior to

acetic ether. See SPIRITS (Medicinal).

=Ethyl, [OE]nanthate of.= _Syn._ [OE]NANTHIC ETHER, PELARGONIC ETHER,

[OE]NANTHATE OF OXIDE OF ETHYL. _Prep._ 1. The oil obtained towards the

end of the distillation of fermented liquors, especially wines, consists,

in a great measure, of the crude ether. It is purified by agitation with a

weak solution of carbonate of potassa, freed from water by a few fragments

of chloride of calcium, and then re-distilled.

_Prop., &c._ [OE]nanthic ether is colourless; lighter than water; boils at

about 500° Fahr.; and has a powerful, intoxicating vinous odour,

resembling that of an empty wine cask or bottle that has been exposed to

the air for some time. It is very sparingly soluble in water, but freely

soluble in alcohol. Its sp. gr. is ·862. As obtained by distillation, it

is united with a little [OE]NANTHIC ACID. 2200 imperial gallons of wine

(about 35 hogsheads) only yielded 2-1/5 lbs. of the mixed oil.

=Ethyl, Oxalate of.= (C_{2}H_{5})_{2}C_{2}O_{4}. _Syn._ OXALIC ETHER,

OXALATE OF OXIDE OF ETHYL; ÆTHER OXALICUS, L. _Prep._ Alcohol and dry

oxalic acid, equal parts, are digested together in a glass flask furnished

with a very long glass tube of small bore, so that the spirit, volatilised

by the heat, may be condensed, and flow back into the flask. After 6 or 8

hours the process is generally complete, and the liquid contains merely a

trace of free acid, from which it may be separated.

_Prop., &c._ A colourless, oily liquid, slightly heavier than water,

boiling at 363° Fahr., only slightly soluble in water, and having an

aromatic smell. Alkalies decompose it. Sp. gr. 1·09.

=Ethyl, Sulphate of.= (C_{2}H_{5})_{2}SO_{4}.

_Prep._ The vapour of pure anhydrous sulphuric acid is passed (with the

usual precautions) into perfectly anhydrous ether; the resulting syrupy

liquid is agitated with a mixture of 4 volumes of water, and 1 volume of

ether, and after repose the upper stratum, which is an ethereal solution

of the sulphate of ethyl, is decanted, and the oxide of ethyl volatilised

by a very gentle heat. The colourless liquid forming the residuum is the

true sulphuric ether or sulphate of ethyl just referred to. It is a very

unstable compound, and cannot be distilled without suffering

decomposition.

=Ethyl, Valerianate of.= C_{2}H_{5}C_{5}H_{9}O_{2}. _Syn._ VALERIANIC

ETHER, VALERATE OF OXIDE OF ETHYL; ÆTHER VALERIANICUS, L. _Prep._ By

passing dry hydrochloric acid gas into an alcoholic solution of valeric

acid. It is a fragrant, volatile liquid, lighter than water, having a high

boiling-point, and a rich fruity odour, said to closely resemble that of

butyric ether or pine-apple oil. It is used to flavour liqueurs, &c.

=ETHYL'AMINE.= NH_{2}(C_{2}H_{5}). _Syn._ ETHYL-AMMONIA. One of the bases

of the ethyl-series, obtained by substituting one atom of hydrogen in

ammonia NH_{3} by ethyl C_{2}H_{5}.

=EUCALYP'TIN.= A peculiar substance existing in Botany Bay kino. A

substance exuded by several species of the _Eucalyptus_. It has been

employed medicinally in diarrh[oe]a.

=EUCALYPTOL.= See EUCALYPTUS.

=EUCALYPTUS.= The _Eucalypti_, of which there are many species, belong to

the natural order _Myrtaceæ_, and are natives of Australia, where they are

known under the names of "gum-trees," or as "stringy-bark trees." The most

interesting and important characteristic of these plants is the power they

undoubtedly possess of correcting, if not of removing, the pestilential

exhalations which are regarded as the origin of the fevers that occur in

marshy localities. This discovery is due to M. Ramel, and was made by him

in 1856.

M. Gimbert, amongst other cases, cites one of a farm, twenty miles from

Algiers, the atmosphere surrounding which was of a very pestilential

character. In the spring of 1867 13,000 eucalyptus trees were planted on

the farm, and M. Gimbert states that since then not a single case of fever

has taken place, the freedom from disease occurring the same year the

plants were placed in the ground, and the good effects commencing whilst

the trees were only two or three mètres in height.

The following is extracted from 'Les Mondes' (1876):--"Between Nice and

Monaco there is a locality so unhealthy that the Paris, Lyons, and

Mediterranean Railway Company have been obliged to change every two or

three months the watchman at a crossing there.

"Plantations of the eucalyptus have been formed there, and at present the

same watchman has resided there for several months with his family without

experiencing the least inconvenience."

Again:--"In the Campagna, about three miles from Rome, there stand some

deserted church buildings and a monastery, the latter having been

abandoned because of the mortality amongst the monks caused by the noxious

exhalations. Some six years since a company of French trappists, having

obtained permission from the Italian Government, planted the grounds in

and around the monastery with eucalyptus trees, and the result is stated

to have been so total an immunity of the building from fever, although

situated in the worst part of the Campagna, that the monastery is now

tenanted, the health of the occupants being, it is said, unimpaired."

The writer in the 'Pharmaceutical Journal,' who contributes this

statement, adds:--"Whether this grand result has been obtained through the

efficacy of the extract of the eucalyptus taken each morning with their

cup of black coffee, or whether it is to be attributed to the effects of

the plantations, I leave to scientific men to determine."[284]

[Footnote 284: Bentley.]

It seems very probable that the effects above described are due to the

eucalyptus having such extensive and far-spreading roots, which suck up

and appropriate the moisture of the surrounding soil, the presence of

which, aided by heat, giving rise to vegetable decomposition, is believed

to be the cause of malarial poisoning.

The avidity of the plant for water is very great; it has been computed

that one tree will absorb ten times its weight of moisture from the

soil.[285] It is most likely owing, at any rate in very large measure, to

this cause, rather than to the supposed antiseptic and disinfecting odours

exhaled by its leaves, that the salubrious effects of the eucalyptus are

due. The blue gum tree, or _Eucalyptus globulus_ (so distinguished because

of the rounded form of the lid which covers its unexpanded flower bud),

has been successfully introduced into Asia, Africa, and Southern Europe.

If, as asserted, it can only exist in a climate where the temperature is

never lower than the freezing point, its domestication (save in

hot-houses) is impossible in our own country.

[Footnote 285: 'Pharm. Journal,' February 5th, 1876.]

[Illustration: EUCALYPTUS GLOBULUS (from the 'Archiv der Pharm.,' 1873, p.

129.)]

The _Eucalyptus globulus_ is a very rapidly-growing tree, and attains to

great proportions. "In some cases it has been known to attain the colossal

dimensions of 350 feet in height and a 100 in circumference."[286]

[Footnote 286: Bentley.]

This magnitude is entirely out of proportion to the size of the seed,

which is very minute; so minute that it has been computed one pound weight

of the seed could produce 162,000 trees. Various preparations of the

leaves and bark of the eucalypti have been introduced into medicine,

which will be found under the respective pharmaceutical preparations. They

were asserted to be specially serviceable in intermittent fevers and

bronchitis. The idea that their efficacy in the former class of disease

was due to the presence in the barks of the eucalypti of an alkaloid

similar to, if not the same as, quinine, has been shown to be an erroneous

one, from the experiments of the Government chemist of Ootacamund (Mr

Broughton), who, after a most careful chemical analysis, failed to

discover either quinine, quinidine, cinchonine, cinchonidine, or the least

trace of any one of the cinchona alkaloids.

When the leaves of the _Eucalyptus globulus_ are held to the light they

reveal the presence of little semi-transparent dots, which are found to be

receptacles for a volatile oil, that may be obtained in large quantity by

submitting the plant to aqueous distillation.

This volatile oil has been examined by Cloez, who found it to consist

chiefly of a substance allied in chemical characters to camphor, which

substance he named _eucalyptol_.[287] Any therapeutic power possessed by

the eucalyptus may be referred to this substance, since, as just stated,

it cannot be due to a bark alkaloid.

[Footnote 287: Messrs Faust and Homeyer state that Cloez's "Eucalyptol" is

a mixture of terpen and cymol.]

Before finishing our notice of the reputed curative effects of the

eucalyptus we may mention that Dr Gimbert employs the leaves instead of

lint for dressing wounds and fetid ulcers, and says he has found them,

when thus used, excellent deodorisers; that another method of employing

the leaves of the eucalyptus consists in having them made into cigarettes,

which are reported to be useful in asthma and bronchial complaints.

Lastly, let us state that another species of eucalyptus exudes a very

astringent substance, which, from its appearance and properties, being so

analogous to kino, has been denominated _Botany Bay kino_. (See

EUCALYPTIN.)

The essential oil of eucalyptus, which, according to the species of the

plant from which it is obtained, varies in colour from light yellow to

light blue, is now largely employed as a diluent for the more delicate

volatile oils used in perfumery.

Many species of the eucalyptus yield excellent timber, possessed of great

hardness and durability, and little affected by moisture. This timber has

the power of resisting the attacks of insects. The wood of the eucalyptus

is also very rich in potash. The maple and the elm, which are regarded as

yielding a large per-centage of this substance, afford only about half as

much as can be obtained from the eucalyptus, this latter tree yielding 21

per cent. of potash.

The barks of different species have also been advantageously utilised for

paper making, as well as for tanning.

In this country eucalyptus seeds are reared in a greenhouse. They may be

sown in a mixture of loam, peat, and ordinary soil, with a sprinkling of

sand on the surface.

The following directions for the cultivation of the eucalyptus in England

were communicated to the 'Medical Times and Gazette' of 1873 by Mr Bennett

Stanford, of Pyt House, Tisbury:--"I have successfully reared from seed

two dozen of these trees, and they are now growing well out of doors. I

obtained the seed five years ago from South Australia, and forced it in a

hothouse; in one year it was four feet high, and now, in its fifth year,

it is growing rapidly in a sheltered position in the park, having attained

a height of thirty feet. The first three years the tree must be taken

under cover in the winter, and the fourth and fifth years should be

protected for several feet up with wisps of hay or straw. When the trees

are kept indoors in winter it should be in an orangery or very high

greenhouse, with plenty of light and a little water."

=EUCHLO''RINE.= A bright-yellow gas, prepared by gently heating chlorate

of potassa with hydrochloric acid. It is probably a mixture of chlorous

acid and free chlorine. Prof. Stone, of Manchester, has found Euchlorine

of a great service as an aerial disinfectant.

=EUGLENÆ.= These are ciliated infusorial animalcules inhabiting ponds and

water-tanks. Sometimes they abound in water in quantities so enormous as

to impart to that fluid a blood-red appearance. The principal species are

the _Euglena viridis_ and the _Euglena pyrum_. Their presence is supposed

to indicate the existence in the water in which they are found, of

decaying animal and vegetable matter upon which they are believed to feed.

=EUPHOR'BIUM.= _Syn._ GUM EUPHORBIUM; EUPHORBIUM (Ph. E.), L. The concrete

resinous juice of the _Euphorbia canariensis_, and other species of the

same genus. It is a powerful acrid, purgative, rubefacient, sternutatory,

and vesicant, and the violence of its action has led to its disuse.

=EU'PIONE.= An ethereal liquid forming the chief portion of the light oil

of wood-tar, and which also exists in the tar obtained during the

destructive distillation of animal substances, and in the fluid product of

the distillation of rape oil. It is separated from these substances by

agitating them with oil of vitriol, or a mixture of oil of vitriol and

nitre, and subsequent cautious distillation. Pure eupione is tasteless,

exceedingly thin, limpid, and aromatic; boils at 116° Fahr.; and is the

lightest fluid known; sp. gr. ·655. It is very inflammable, burns with a

very bright flame, and gives a transient greasy stain to paper. It is

isomeric with hydride of amyl. Other volatile hydrocarbons of like origin

are often confounded with eupione by chemical writers.

=EUPYR'ION.= Any contrivance for obtaining instantaneous light; as a

lucifer match, &c.

=EVAC'UANTS.= _Syn._ EVACUANTIA, L. Medicines which augment the secretions

or excretions. CATHARTICS, DIAPHORETICS, DIURETICS, EMETICS, ERRHINES,

EXPECTORANTS, and SIALOGOGUES, belong to this class.

=EVAPORA'TION.= The conversion of a fluid into vapour by means of heat,

diminished atmospheric pressure, or exposure to a dry atmosphere.

Evaporation is had recourse to--1. For the vapour as a source of heat or

power, as in the case of steam-boilers, &c.;--2. To separate volatile

fluids from impurities or other bodies, which are either fixed or less

volatile;--3. To recover solid bodies from their solutions, as in the

preparation of extracts, chemical salts, &c.;--4. To concentrate or

strengthen a solution by the expulsion of some of the fluid matter that

forms the menstruum;--5. To purify liquids by the dissipation of the

volatile matters which may contaminate them.

It is found that, under ordinary circumstances, evaporation is confined to

the surface of the heated liquid, and is therefore slower or quicker, in

proportion to the extension of that surface. Hence has arisen the adoption

of wide, shallow vessels for containing fluids during their exposure to

heat for this purpose. Evaporation proceeds most rapidly when a current of

air (especially hot and dry air) is made to pass over the surface of the

fluid; as, in this ease, the vapour is prevented from resting upon the

surface, and impeding the process by its pressure. For a similar reason,

liquids evaporate more rapidly in vessels partially covered than in open

ones. In the former case the cool incumbent air condenses and throws back

a portion of the vapour, which thereupon, besides its cooling action,

offers mechanical resistance to the diffusion of the vaporous particles as

they arrive at the surface of the liquid. In the latter case these

obstacles are avoided, and the impetus of the vapour pouring forth from a

contracted orifice (or pipe), not only readily overcomes the pressure of

the atmosphere, but offers less surface for its cooling action, until it

has passed much beyond the points at which it can exert any influence on

the fluid from which it has escaped. In this way the chemical action of

the atmosphere on the liquid operated on is also considerably lessened. On

the small scale, shallow capsules of glass, wedgwood-ware, porcelain, or

metal, are commonly employed as evaporating vessels, and these are exposed

to heat by placing them over a lamp, or naked fire, or in a water bath, or

sand bath, according to the temperature at which it is proper to conduct

the process. On the large scale, high-pressure steam is usually employed

as the source of heat. The term 'spontaneous evaporation' is applied to

the dissipation of a fluid by mere exposure in open vessels, at the common

temperature of the atmosphere, and without the application of artificial

heat. The celerity of this species of evaporation wholly depends on the

degree of humidity of the surrounding air, and differs from the former, in

which the rate of evaporation is proportionate to the degree of heat at

which the process is conducted, and the amount of pressure upon the

surface of the liquid. Evaporation '_in vacuo_' (as it is called) is

conducted under the receiver of an air-pump, or in an attenuated

atmosphere, produced by filling a vessel with steam, by which means the

air is expelled, when all communication with the external atmosphere is

cut off, and the vapour condensed by the application of cold. Fluids are

also evaporated in air-tight receivers over sulphuric acid, by which they

are continually exposed to the action of a very dry atmosphere. When such

a receiver is connected with an air-pump in action, evaporation proceeds

with increased rapidity, and intense cold is produced. It appears, from

the experiments of Dr Ure, that "if the bottom of a pan, and the portion

of the sides immersed in a hot fluid medium (solution of chloride of

calcium, for example), be corrugated, so as to contain a double expanse of

metallic surface, that pan will evaporate exactly double the quantity of

water, in a given time, which a like pan, with smooth bottom and sides,

will do, immersed equally deep in the same bath. If the corrugation

contain three times the quantity of metallic surface, the evaporation will

be threefold in the above circumstances. But if the pan, with the same

corrugated bottom and sides, be set over a fire, or in an oblong flue, so

that the current of flame may sweep along the corrugations, it will

evaporate no more water from its interior than a smooth pan of like shape

and dimensions placed alongside it in the same flue, or over the same

fire."

In the laboratory, steam heat is now almost exclusively employed. Copper,

or tinned, glazed, or silvered coppered pans, boilers, and stills, are

surrounded by a 'jacket' of cast iron, and high-pressure steam admitted

between the two. By due management of the supply-cock, a range of

temperature may be thus obtained extending from about 90° to 325° Fahr.

It is found that, under ordinary circumstances, 10 square feet of heated

surface will evaporate fully 1 lb. of water per minute; and that a thin

copper tube exposing 10 feet surface will condense about 3 lbs. of steam

per minute, with a difference of temperature of about 90° Fahr. This is

equal to 30° Fahr. per lb.; and, consequently, the heat of the steam

employed to produce the evaporation should be 212° + 30° = 242° Fahr.

An attention to the facts and principles thus briefly explained above will

be found of great value in the laboratory.

=EXCIP'IENT.= See PRESCRIPTION.

=EXCI'TANTS.= See STIMULANTS.

=EXCORIA'TIONS.= _Syn._ _Sprays_, CHAFINGS.

In _surgery_ and _pathology_, superficial injuries or affections of the

skin, consisting of the removal of the scarf-skin or cuticle, accompanied

with more or less irritation and slight inflammations. When arising from

rough friction or attrition, they are more commonly called abrasions.

Young children are very apt to be chafed under the arms, behind the ears,

between the thighs, and in the wrinkles and folds of the skin generally,

unless great attention is paid to cleanliness, and wiping the skin

perfectly dry after washing them. Whenever there is a tendency to

excoriations of this kind, either in adults or children, a little finely

powdered starch, or violet powder, applied by means of a puff, or a small

bag of muslin, once or twice a day, will generally remove them, and

prevent their occurrence in future. Mild unguents, as cold cream, or

spermaceti cerate or ointment, may also be used with advantage. The

preference should, however, be given to the remedies first named, from

their not soiling the linen. See ABRASION.

=EXCRETA.= The excrementitious matter evacuated from the bowels varies of

course in composition and quantity according to the food from which it is

derived.

Berzelius found a sample analysed by himself to yield about seventy-five

per cent. of water, the remainder being made up of alimentary waste, and

biliary matter. A large amount of phosphates of calcium and magnesium was

found in the ash remaining after the incineration of the solid matter. A

specimen of fæcal matter examined by Playfair yielded 15 per cent. of

nitrogen and 45 per cent. of carbon. Marcet states that he has obtained

from excrement a crystallisable body possessing an alkaline reaction; to

which he gives the name _excretin_; also a fatty substance, which

he terms _excretolic acid_. To excretin he assigns the formula

C_{7}_{8}H_{1}_{5}_{6}SO_{2}; the composition of the acid has not been

determined.

Hinterberger has succeeded in getting excretine (excretin), free from

sulphur, and gives as its simplest formula C_{2}_{0}H_{3}_{6}O; which

shows a close resemblance to cholesterin, C_{2}_{6}H_{4}_{4}O.

But cholesterin is less easily dissolved in vinegar than excretin, and the

solution deposits crystals which, when viewed by the microscope, are found

to be beautiful silky six-sided prisms, while the excretin solution yields

round masses.

Treated with bromine, excretin gave a crystalline body having the formula

C_{2}_{0}H_{3}_{4}Br_{2}O; but the author did not succeed in preparing a

chlorinated compound of excretin.

In the excreta of carnivorous animals no excretin has been discovered,

although a substance resembling it has been found. Cholesterin has been

obtained from the fæces of the crocodile, but no urates; whilst the

excreta of the boa contain urates, but are destitute of cholesterin.

The fæces of animals that live on vegetables contain neither excretin,

butyric acid, nor cholesterin.

The excreta of birds and serpents, which mixed with the secretion from the

kidneys, are discharged from the animals by the cavities, are very similar

to urine, and consist chiefly of alkaline urates and earthy phosphates.

The excrements of insects consist mainly of the remnants of the tissues,

animal or vegetable which they have swallowed as food, mixed with

constituents of the urine, provided the insect has no special urinary

organs.

Briéger examined the fæces of healthy persons, and of convalescents, and

found in addition to acetic, butyric, and isobutyric acids, small

quantities of phenol and indol, and a new crystallisable body, which he

terms _skatol_ (_skatos_, fæces). It crystallises in irregular-dentate

shining plates, resembling indol, which by frequent recrystallisation from

hot water, can be obtained snow white. Skatol forms the chief constituent

of the volatile aromatic components of human fæces. Fæces of dogs (whether

fed on meat or bread diet) contained no skatol, but indol, and in addition

a yellow oil, with a revolting and peculiarly irritating smell.

Briéger has not yet been able to analyse this yellow oil, although it

forms the chief volatile constituent of dogs' fæces. He has repeatedly

obtained it from distillation from human pathological fluids. In the

pancreas after putrefaction, and in the fæces of typhus patients, no

skatol was found. The author considers skatol identical with the substance

which Secretan obtained by the decomposition of egg albumen under water

for six months.

Skatol injected under the skin of rabbits, passes out in the urine as a

substance yielding colouring matter. Skatol is believed by the author to

be the substance in human urine which, according to Jaffé, yields a red or

violet colour on the addition of hydrochloric acid and chloride of lime.

Phenol, the author finds, is a constant component of human fæces. The

above results show that specific products of decomposition are normal

components of intestinal digestion.[288]

[Footnote 288: 'Deut. Chem. Ges. Berg.,' x, 1027-1031.]

Liebig calculated that the daily average amount of fæcal matter passed by

a man is 5-1/2 oz; Lawes says that it averages in healthy male adults, 4·2

oz; Parkes estimates it (in Europe) at 4 oz. on the average; Letheby at

2·784, and Frankland at 3 oz. In India, a native on the average excretes

as much as 12 oz., this increase over the above quantities being due to

the large proportion of rice and farinaceous food of which the Hindoos'

diet consists.

The daily average amount of urine excreted by a human being has been given

by Lawes at 46 oz.; Parkes places it at 50 oz. by measure for each male

adult; Letheby at 31·851, and Frankland at nearly 40 oz. by measure.

According to Parkes' figures a population of a thousand persons, would

thus void daily 156 lbs. of solids, and 260 gallons of urine; or 25 tons

of fæces, and 91,250 gallons of urine per annum; whilst according to

Letheby, from the same number of people, the daily discharge would be 2266

lbs. avoirdupois of urine and 177·5 lbs. of fæces.

Messrs Lawes and Gilbert estimate the manurial value of the urine and

fæces together at 6s. 8d. per annum for every individual, which

corresponds to a yearly produce of about 10 lbs. of ammonia; but Messrs

Hoffman, Witt, and Thudichum assess it at 8s. 6d. for a mixed population

of both sexes and of all ages, which they say represents about 13 lbs. of

ammonia.

Fæcal matter decomposes much more rapidly when mixed with urine than it

would otherwise do, ammonia and fetid gases being given off in

considerable quantities. Should much water be also present, and the

temperature moderately high, light carburetted hydrogen, carbonic

anhydride, nitrogen, and sulphuretted hydrogen are likewise evolved.

Unless human excreta be effectually as well as speedily removed from the

dwellings, streets, &c., of a community, that community will assuredly pay

the penalty of their neglect in the shape of health seriously endangered

and deteriorated. If this be so with healthy evacuations, the peril

becomes considerably intensified when the excreta are discharged by

patients labouring under contagious or many other diseases. See URINE,

SEWAGE.

=EX'ERCISE= is essential to the healthy performance of the functions of

both body and mind. Without it, the stomach acts feebly, the bowels become

inactive, and the circulation of the blood languid and imperfect; the

chest contracts, the respiration becomes impeded, the brain is

insufficiently supplied with pure arterial blood, the mind grows

lethargic, the complexion assumes a sickly and effeminate hue, and the

features generally lack the energy and expression which they possess in

perfect health. With exercise, the bodily functions are performed with

vigour and regularity, the constitution is thereby strengthened, and the

attacks of disease repelled. By exercise the mind too is excited to

healthy action, its gloomy reveries are dispelled, and the fair face of

creation is presented to the mind's eye in its proper hues. It robs undue

mental exertion of half its injurious effects upon the body, whilst it

stimulates and directs it in its proper course. It improves the temper,

and humanises the character. The disposition is refined, the passions

restrained, violent emotions checked, the habits improved, and the

personal charms promoted under the stimulus of judicious exercise.

To females, bodily exercise is even more necessary than to males. The

disposition and education of females are such as tend to produce habits of

sloth and indolence to a greater degree than in the other sex. Hence to

them exercise is doubly important--it is inseparable from health. The more

retiring dispositions of females lead them almost unconsciously into

habits of inactivity, which, above all, they should endeavour to shake off

and avoid. By so doing--by replacing habits of indolence and inactivity by

liveliness and moderate exercise, the development of the body will be

promoted, additional grace and elegance imparted to its natural movements,

and the enjoyments arising from both mental and bodily health increased,

whilst disease and deformity will be prevented by the removal of their

cause.

The necessity of exercise exists equally in every grade of society and age

of life. Those who are engaged in sedentary employments or in-door

occupations, should particularly seek refreshing out-door exercise during

the periods of relaxation from their diurnal duties. To the studious and

delicate of both sexes, this is absolutely necessary to preserve the

health and vigour of the body.