ALCOHOL.

107

Iii the London Pharmacopoeia alcohol is directed to he procured bydissolving one pound of chloride of calcium (fused) in a gallon of rectifiedspirit (sp. gr. 0.838): from this seven pints and five fluid ounces ofalcohol (sp. gr. 0'815) are to be distilled. In this process the chlorideof calcium, (which is very soluble in spirit) having a powerful affinity forwater, prevents the rise of this fluid during distillation, and thus thespirit is deprived of nearly the whole of its water.

Properties. —Alcohol is a limpid, colourless, inflammable liquid,having a peculiar and penetrating odour, and a burning taste. Its sp. gr.at 59° 1'., is 0-7947 ; at 62^° F., 0791 ; at 173° F., it is only 0-73809(Dumas, Traite cle Chimie, t. 5, 462).

No means of solidifying it are at present known. It boils at 173° F.:every volume of the boiling liquid gives 488'3 vols. of vapour calculatedat 212° F. The sp. gr. of alcohol vapour by experiment is P6133, bycalculation; according to Dr. Thomson, P5972.

It is very combustible. In atmospheric air it burns with a pale blueflame, giving out a very intense heat, and generating carbonic acid andwater, but depositing no soot. The colour of the flame may be variouslytinted—as yellow by chloride of sodium, violet by chloride of potassium,green by boracic acid or a cupreous salt, carmine red by chloride oflithium, crimson by chloride of strontium, and greenish yellow by chlo-ride of barium. One volume of alcohol vapour requires, for its completecombustion, three volumes of oxygen gas, and yields two volumes of car-bonic acid gas and three volumes of aqueous vapour. If alcohol vapourmixed with atmospheric air or oxygen gas be passed through a tubeheated to dull redness, the products are carbonic, acetic, and aldehydric*acids, water, and a peculiar substance having a disagreeable, pungentodour {Liebifj). By the combustion of alcohol vapour by spongy plati-num the products are aldehyde, acetal, acetic acid, and acetic ether{Liebig ).

Alcohol has a strong affinity for water: hence it abstracts this fluidfrom the atmosphere, and precipitates from their watery solution thosesalts (e. g. sulphate of potash) which are not soluble in spirit: while, onthe other hand, water precipitates from their alcoholic solution thosesubstances (e. g. resin and oil) not soluble in water. By the mixture ofalcohol and water, heat is evolved, while air-bubbles are so copiouslydeveloped, that for a few moments the liquid appears turbid. When cold,the resulting compound is found to possess a greater density than themean of its consti uents : but as the condensation varies with the pro-portions of alcohol and water employed, the sp. gr. of the resulting com-pound can be ascertained by experiment only. The maximum conden-sation is obtained by mixing 54 vols. of alcohol with 4977 vols. ofwater: the resulting compound measures 100 vols., so that the condensa-

* Aldehydric acid (Aldehydsiiure) is a term applied by Liebig and Poggendorf(Handworierbuch der Clieniie) to the Lampic acid of Daniell. It is derived fromAlcohol de hydroyenatus. Its probable formula is C 4 H 3 O 2 + H.

f Aldehyd (Aldehyd ), another term introduced by the same chemists to indicate afluid composed of C 1 IP O 2 .