198

ELEMENTS OF MATERIA MEDICA.

tion is 3'77. If we regard this as a definite compound of alcohol andwater, its composition may thus be stated:—

Rudberg.

Eq.

Eq. Wt.

Per Cent.

Vols.

Weight.

Alcohol.

. . . 46 . . .

. 54-00 . .

. . 42-91

Water.. .

. . . 54 . . .

. 49-77 . .

. . 49-77

Terhydrate of Alcohol . .

. . 1 . . .

. . . 50 . . .

. . . 100 . . .

. 100-00 . .

. . 92-68

Alcohol combines with certain salts (as the chlorides and nitrates) toform definite compounds, which have been termed alcohates, in which thealcohol appears to act as a substitute for the water of crystallization.

Alcohol is a solvent of many organic substances, as volatile oil, fixedoil, resin, extractive, most varieties of sugar, many nitrogenous organicacids, the vegetable alkalies, urea, caseum, gliadine, leucine, picromel,and osmazome. It prevents the putrefaction of animal substances, andis, in consequence, extensively employed in the preservation of anatomicalpreparations. Its efficacy is imperfectly understood. It acts, in part atleast, by excluding air (oxygen) and water,—die two powerful promotersof putrefaction; for when animal substances are immersed in spirit, thisfluid mixes with and replaces the water with which the tissue was im-pregnated ; and thus prevents putrefaction by removing one of the essen-tial conditions to its production, namely, the presence of water. Itsattraction for water, and its power of coagulating albuminous substances,are properties which probably assist powerfully in rendering it an anti-septic. Alcohol and rectified spirit of wine give greater firmness to, andwhiten the animal tissues. The latter property is objectionable in thepreservation of some morbid specimens, as gelatiniform cancer ( cancergelatiniforme or areolaire of Cruveilhier, —the mattere colloid, of Laennec).A mixture of one part rectified spirit and three parts water will, however,preserve specimens of the last-mentioned disease in a transparent condition.

Characteristics. —Alcohol and ardent spirits are recognized bytheir inflammability, odour, taste, and miscibility with water. In orderto detect alcohol in liquids supposed to contain it, let the suspectedliquor be submitted to distillation with a gentle heat (as from a vapouror water bath), and to the distilled liquid add dry carbonate of potash,to abstract the water. The alcohol floats on the surface of the alkalinesolution, and may be recognized by the characters above mentioned.

Composition. —The elementary constituents of alcohol are carbon,hydrogen, and oxygen.

Eq. Eq.Wt.

Per Cent. Dumas&Boullay. Saussure.

Vol.

Sp. Gr.

Carbon . 2 .

. 12 .

. 52-18 .

. 52-37 .

. 51-98

Carbon vapour.

lor 2

0-8333

Hydrogen 3 .

. 3 .

. 13-04 .

. 13-31 .

. 13-70

Hydrogen gas .

. . 3

0-2083

Oxygen . 1 .

. 8 .

. 34-78 .

. 34-61 .

. 34-32

Oxygen gas . .

. 0-5

0-5555

Alcohol . 1 .

. 23 .

. 100-00 .

. 100-29 .

. 100-00

Alcohol vapour

. 1

1-5972

Chemists are not agreed as to the manner in which these constituents aregrouped. By some these elements are regarded as forming one equiva-lent of olefiant gas, and one equivalent of water: others consider alcoholto be a compound of one equivalent of a — carbo-hydrogen (called bysome etherine, by others tetarto-carbo-hydrogen or quadri-hydrocarburet),and two equivalents of water; while a third class of philosophers view