dark-coloured solution or wort. It is cooled to 70°, placed in the fermenting tun, and mixed with yeast. The fermented wort, or wash, constitutes the source both of beer and spirits. If the alcohol is allowed to remain in the wash, the fluid is termed a fermented liquor.

Small Beer is a dilute or weak wort fermented, and contains 1 per cent. of alcohol of specific gravity 825. Ale is a stronger wort, containing 7 per cent. of alcohol. Porter contains 44 per cent. It is made with malt dried at a high temperature, and slightly charred, from which it derives its colour. Brown stout contains 63

per cent. Burton ale 8 per cent.

Wines are prepared by fermenting the expressed juice of the grape. Like beers and ales they vary in strength and in flavour, according to the concentration and source of the juice. Champaigne is one of the weakest wines; it contains 12 to 13 per cent. of alcohol. Hock, 13 per cent. Claret, 13 to 16. Sherry, 19 per cent. Port, 23 per cent. Hence 5 glasses of sherry contain nearly 1 of alcohol; and 4 of port somewhat less than 1 of alcohol.

Spirits. When the worts are heated in a still, supplied with a refrigerator and receiver, the alcohol passes over and leaves the spent wash in the still. Whisky is prepared from barley and oats. Highland whisky seems to derive its peculiar flavour from the malt being made and dried with peats, which give out creasote, and other volatile oils, by the combustion of the vegetable matter of which they are composed. Brandy is prepared from wine, and flavoured with burnt sugar. The name is derived from the German brand wein, burnt wine. Rum is distilled from the sugar cane. Gin, Hollands, and Scheidam are distilled from barley, and flavoured with juniper, turpentine, and other substances. The two latter names are derived from the localities of their preparation. Samshoo, a Chinese spirit obtained from fermented rice. Arrack, a similar impure spirit made in Bengal. British brandy is whisky said to be flavoured with nitric ether, and various mixtures.

A

Characters. Common spirits, and whisky, have a specific gravity of 910 to 915, containing 50 per cent. of alcohol. When they have been distilled their density becomes 890 to 880. second distillation produces rectified spirit, of the spec. grav. 843 to 835, with 82 to 85 per cent. of alcohol. To remove the whole of the water, it is necessary to distil with chloride of calcium, or quicklime, salt of tartar (carbonate of potash), or to expose rectified spirit in a vacuum along with quicklime. The spirit is placed in one basin, and the lime in another; the air is pumped out until the spirit begins to boil, and is left for some days at the usual temperature. The lime takes the water and leaves the spirit (absolute alcohol of 794). If a bladder be filled with spirit,

tied up, and hung in a warm apartment for some days, water escapes through the bladder and leaves a strong alcohol. Proof spirit of the excise has a spec. grav. of 91833, and is said to be above or below proof when it is stronger or weaker than this. The term proof is derived from the old mode of testing spirit: the spirit was poured over gunpowder and ignited; if the powder exploded towards the end of the combustion, the spirit was said to be above proof; if it did not explode, it was below proof. At present, when we say that spirit is 10 over proof, we mean that 100 gallons to be reduced to proof strength, would require the addition of 10 gallons water, while 10 under proof shows that 10 gallons of water require to be subtracted to bring it up to proof. The strength of spirits is determined by taking the specific gravity either by means of the bottle (see page 7.), or more rapidly by the hydrometer. Alcohol is a transparent, colourless, volatile fluid, with a peculiar pleasant smell, acting first as an intoxicating agent when taken internally, and in larger quantities as a poison. Absolute alcohol boils at 171°, of 914 at 1810, of 831 at 175°. It has never yet been rendered solid by the greatest cold and pressure; it does not conduct electricity; when mixed with water, heat is given out and the bulk of the fluid contracts; it rapidly extracts water from the air, and takes water from animal and vegetable substances when they are immersed in it; hence its use in preserving these bodies from decay, as in anatomical museums. Alcohol is much employed on this account; and, from its being a convenient solvent, in pharmacy, to form tinctures; thus we have tincture of iodine, tincture of sesquichloride of iron, tincture of rhubarb, aloes, &c. It dissolves various salts, as nitrates of lime, cobalt, copper, alumina, magnesia, chlorides of Zn, Al, Mg, Fe, Cu; it crystallizes with certain salts, as CaCl, MgO NO,, CaO NO,, Mn Cl, Zn Cl, and forins alcoates. — ( Graham.)

Experiments.-1. Dissolve a small portion of camphor in alcohol, and then pour water into it; the camphor is removed from the alcohol, and swims on the surface. 2. Dissolve some chloride of strontium in alcohol, and set fire to the solution in a porcelain basin; the flame has a fine crimson colour, proving the solution of the salt. 3. Take a jar or tumbler; pour into it half a tea spoonful of alcohol; place a plate of glass over the mouth of the tumbler, and agitate until the fluid is invisible; then ignite the vapour of the alcohol, and place the open end of the tumbler in water. The water rises into the glass, showing the formation of a vacuum by the combustion. It is upon this principle that cupping glasses extract blood from the body.

Bread making, Panification. - The usual method of making bread is to mix yeast with dough or moist flour, and allow it to ferment; the sugar is converted into alcohol and carbonic acid. The gas is generated throughout the dough; but cannot escape,

from the adhesiveness of the mass. But when placed in the oven at 450°, the gas expands, and finally escapes, leaving the whole of the bread a mass of little bladders or vesicles. A good baked loaf, or a well-raised loaf, is therefore bread in which the carbonic acid has been equally generated throughout the mass; but by the usual method the CO, is formed at the expense of the sugar of the flour, occasioning the loss of at least 63 per cent. Any method of diffusing carbonic acid through dough, will form superior bread to that prepared by fermentation. Soda scones are made by mixing bicarbonate of soda with the flour, and then baking the mass up with buttermilk; the acid of the milk displaces the CO2. Unfermented bread is made by mixing 320 grs. of bicarbonate of soda with 4lbs. of flour, dissolving 300 grains of common salt in 35 ounces of water, and adding to it 61⁄2 fluid ounces of hydrochloric acid, and mixing up intimately, and then heating in the oven. (See Experimental Researches, p. 183.) Gingerbread and light cakes are often raised by means of carbonate of ammonia, which is converted into a gas by the heat.

5

Ether, Oxide of ethyle, Sulphuric ether (C, H, O, or EO).—This fluid is supposed to be the basis of alcohol. It is usually prepared by mixing 5 parts of alcohol of 822 specific gravity, with 9 of sulphuric acid in a retort, and distilling; by having a tube passing through a cork in the tubulure and descending beneath the surface of the fluid, a fresh supply of alcohol can be gradually added. The distilled fluid contains alcohol and water; to remove the alcohol, it is mixed with its own bulk of water, when the alcohol dissolves in the water, and the ether swims on the surface. The ether may be deprived of all its water by distillation over caustic potash or chloride of calcium. The theory of the process is, that when SO, comes in contact with alcohol, it forms a fluid double salt, sulphate of ethyle and sulphate of water (EO SO, HO SO,); and the proof of this is, that if we add to a boiling mixture of the two, carbonate of barytes, and evaporate, we get crystals of double sulphate of ethyl and sulphate of barytes (EO SO3, Ba O SO,), where the basic water has been replaced by the barytes. By distillation the double fluid salt is decomposed into EO and water, while the SO, remains. The various acids form similar double salts, which are termed ethers. Phosphoric acid gives 2 HO EO PO Nitrous ether consists of EO NO, Oxide of ethyle is thus said to be the oxide of an organic radical.

Characters. Colourless, limpid fluid, with a fragrant odour, and hot pungent taste; exceedingly volatile, disappearing even when poured from one vessel to another; evaporating with great rapidity when poured on the band, and producing cold; hence it is used in cooling lotions in surgery. It is also much used in cupping, to produce a vacuum, by pouring half a tea-spoonful

VINEGAR OR ACETIC ACID.

175

into a cupping glass, agitating till it disappears, igniting it, and rapidly inverting it over the part which has been scarified by the lancets. Boils at 96°, and in vacuo at 20°. Specific gravity of vapour 2.583; specific gravity of fluid 715 at 68°, 724 at 54°; 1 part of ether dissolves in 10 water; it mixes with alcohol and ethereal oils in all proportions.

Experiments. 1. When admitted to oxygen it doubles the volume of the gas, and 1 part of this expanded oxygen, if mixed with 3 parts of pure oxygen, explodes when ignited, water and carbonic acid being formed. 2. A few drops of ether

let fall on a hot brick in a dark room, produce a luminous appearance. 3. Flameless lamp. — If very thin platinum wire be formed into a coil, by winding it round a thin glass rod, and be then adjusted so as to inclose the cotton wick of a lamp containing ether; if the wick be ignited, and blown out after the lapse of a minute, the wire will continue red hot as long as the ether lasts. The products of this action are acetic, formic, and aldehydic acids, possessing a very acrid odour. 4. When ether is passed through a red-hot glass tube, it is converted into aldehyde, olefiant gas, and carburetted hydrogen (CH). Tests of purity.— Ether should be neutral to test paper; it should not become milky when mixed with water, and should not diminish in bulk when its own volume of water is added to it. It is used as an antispasmodic in asthma, in doses of half a teaspoonful mixed with water. It is also employed to produce insensibility in operations. It acts, when a drachm of it is placed in a bladder, and breathed, exactly like laughing gas.

Acetous or Vinegar Fermentation. When wine and beer are carefully corked up they may be preserved without injury for many years; but if they are imperfectly corked, or are exposed to the air, they speedily become sour by the formation of vinegar or acetic acid: hence oxygen obviously takes an active part in this change. Pure spirit never becomes sour by exposure to the air; the presence of albuminous matter is necessary. It has been also observed that when alcoholic vapour is brought in contact with spongy platinum and air, acetic acid is produced, the metal becoming red-hot. The change is simple: :

1 alcohol and 4 oxygen=C1H2O+HO and 04

become

3

1 hydrous acetic acid and 2 water = C1H2O2+ HO and 2HO. Two atoms of hydrogen have thus been removed from the alcohol, and 20 added; while the H, have united with O, from the atmosphere, and formed water. This action is said to be by replacement; and the formula of acetic acid may be written C1H2O

+ HO. It would appear, however, that acetic acid is not 02 formed at once, but that there is an intermediate stage, the pro

duction of aldehyde, while the H, are removed and have not been succeeded by the oxygen; its formula is C,H,O, HO. It is a colourless, highly fluid liquid, with a very peculiar smell. Specific gravity 79; boiling point 7110; mixes with water, alcohol, and ether; neutral, combustible. It may be formed by dropping a few crystals of chromic acid into alcohol, as described under chromium, or by distilling alcohol, bichromate of potash, or black oxide of manganese, and sulphuric acid. It is obtained purest by uniting it with ammonia, and distilling the compound with SO3. When kept at 32° it changes into crystals, elaldehyde; when retained at the ordinary temperature, metaldehyde, in colourless needles, appears. Chloral (C4CIO HO) formed by the action of chlorine upon alcohol.

Spec. grav. 1.5.

Oily fluid.

Experiments. If we add a few drops of aldehyde to water in a tube, some solution of nitrate of silver, and a little ammonia to precipitate the oxide, and boil, the metallic silver is deposited on the inside of the tube, giving it a fine brilliant silvery appearance. The whole of the silver is not reduced; one half of it remains united to aldehydic acid C4H3O2 (by the action of CH ̧O and 2AgO becoming C4H,O, AgO, and Ag. Several other bodies possess this power of reduction; and a patent exists for silvering looking-glasses by the use of certain oils. When aldehyde is heated with potash or ammonia, the resin of aldehyde is obtained. When NH, dry, is passed into aldehyde crystals of ammonia-aldehyde separate, and if a current of SH be passed through these crystals in solution, crystals of Thialdine, (C12H1NS4), a base appear which, when heated with slaked lime, yield leucol or leucoline, one of the bases of coal tar. Acetal (CHO) by spongy Pt on alcohol.

Acetic Acid, Vinegar, Pyroligneous Acid, Wood Vinegar (C1H2O2HO, 7.5), may be obtained pure and strong by distilling acetate of lead, copper, or soda, with SO3. It is a clear, colourless fluid, and crystallizes at 45° in flat plates, with a sp. grav. of 1063; taste very sour; blisters the skin; it unites with various proportions of water, and forms vinegar of different degrees of strength. 1. Malt Vinegar is made by mashing malted barley with water at 170°, fermenting, placing the liquor in casks, leaving the bungs out; in two or three months the vinegar is formed. 2. Wine Vinegar is formed by mixing the wine to be acidified with vinegar already formed in casks supplied with apertures for the admission of air. 3. Spirit Vinegar, or Quick Vinegar Method, is executed by filling a cask with beech wood shavings, moistened with strong vinegar. A mixture of part of spirits (sp. grav. 843), 5 water, and 1 thousandth part of yeast or honey, is allowed to drop continuously through the cask; the temperature rises to 100°, and the whole of the spirit is in 24 to 36 hours converted into acetic acid, by passing two or three times through the shavings. The