ALCOHOL.

199

this liquid as a hydrated oxide of a -j carbo-hydrogen ( ethereum of Kane,ethule of Berzelius ), or as the hydrate of ether; for ether is by themregarded as the oxide of ethereum. The latter opinions involve thenecessity of assuming the equivalent for alcohol to be 46 ; that is, doublethe amount stated above. The following table illustrates the views juststated:—

Per

Eq. Eq.Wt. Cent.Olefiant gas 1..14.... 60'7Water.1.. 9.... 39*3

Alcohol.1.. 23.. ..100-0

Per

Eq.Eq.Wt. Cent.Etherine 607

Water.. 2..18_39*3

Per

Eq.Eq.Wt. Cent.

Ethereum 1..29_63*04)

Oxygen.. 1.. 8 —17*395Water .. 1.. 9-19*56

Per

Eq.Eq.Wt.Cent.

Ether ..1..37_80*43

Water..1.. 9....19*56

Alcohol. 1..46.. ..100*0

Alcohol.. 1..46_99*99

Alcohol 1..46_99*99

Alcoholometry. —The value of ardent spirit is, of course, propor-tionate to the quantity of alcohol contained therein; and, therefore, aready mode of estimating this is most desirable. The alcoholometricalmethod usually ado])ted consists in determining the sp. gr. of the liquidby an instrument called the hydrometer. That employed in this country,in the collection of the duties on spirits, is called Sykes s hydrometer.Spirit having the sp. gr. 0 920, at 60° F. is called proof spirit ; thatwhich is heavier is said to be under proof \ while that which is lighter iscalled over proof. The origin of these terms is as follows :—Formerly avery rude mode of ascertaining the strength of spirit was practised,called the proof: the spirit was poured upon gunpowder, in a dish, andinflamed. If at the end of the combustion the gunpowder took fire,the spirit was said to be above or over proof; but if the spirit containedmuch water, the powder was rendered so moist that it did not takefire: in this case the spirit was declared to be, below or under proof.As spirit of different strengths will or will not inflame gunpowder,according to the quantity of spirit employed, it became necessary to fixthe legal value of proof spirit: this has been done, and proof spirit(spiritus tenuior, Pli. L.) is defined, by act of parliament, to be such thatat the temperature of 51° F. thirteen volumes of it weigh exactly asmuch as twelve volumes of water. According to this definition thesp. gr. at 60° F. is 0'920, and spirit of this strength consists of

By Weight. Sp. Gr.

Alcohol. 49. 0*791

Water. 51. 1*000

Proof spirit.. 100 . 0*920

Proof spirit may be prepared by adding three pints of distilled water, at60°, to five pints of rectified spirit, sp. gr. 0'838. Compounded spirits(e. g. gin) are not allowed (6 Geo. 4, cap. 80, sect. 124) to be kept orsent out stronger than 17 per cent, under proof; but gin, as usuallysold by the rectifier, is 22 per cent, under proof. Distillers are notpermitted (6 Geo. 4, cap. 80. sect. 81) to send out spirits at any otherstrength than 25 or 11 per cent, above, or 10 percent, below proof.The legislature (6 Geo. 4, cap. 80, sects. 101 & 114) has also definedspirits of wine to be of the strength of 4-3 per cent, over proof atthe least. The liquid sold as rectified spirit has usually a sp. gr. offrom 54 to 00 or 64 per cent, over proof. Hatters employ that at 54or 56; varnish-makers that at 58 per cent, over proof, limn andbrandy, as usually sold, are 10 per cent, under proof. The act