ALCOHOL, is the chemical name, (pro• bably derived from the Arabic), for ardent spirit. Alcohol is the intoxicating principle of beer, wine, and fermented liquors in general; and when they are subjected to distillation, the alcohol and a considerable quantity of water are vaporized and condensed together. The distilled products have different names and properties according to the substances yielding them.
It is explained under FERMENTATION, that when that process is going on, a compound of carbon, hydrogen, and oxygen, previously existing in the form of sugar, is decomposed, and out of it are formed two other compounds, —alcohol and carbonic acid. It is in this way that alcohol is obtained for use. The alcohol of commerce is, however, always mixed with water, on account of the great affinity between them; and it is a difficult chemical process to produce absolute or pure alcohol.
Alcohol, in its absolute or anhydrous state (free from water), is a limpid, colourless liquid, of an agreeable smell, and a hot pun gent taste. It is composed of carbon, hydro gen, and oxygen. Its specific gravity is 0.791 at 08°F., or 0.7047 at F. It has never been frozen, although exposed to a tempera ture below zero, or below the freez ing point of water. It is extremely volatile, producing considerable cold during evapora tion ; the degree of cold is proportional to its purity. Heat expands alcohol in a greater degree than it does water, for 100,000 volumes become 101,168 by being heated from 32' to 100°; whereas an equal bulk of water heated to the same degree is increased only to 100,008. Under the average atmospheric pressure alcohol boils at about but in the vacuum of the air-pump, ebullition occurs at 00° and even below it. Alcohol, and the
vapour arising from it, are extremely inflam mable; it burns with a lambent flame, the colour of which depends upon the strength of the alcohol ; the blue tint prevails when it is strong, and the yellow when weak. Although the flame of alcohol yields but little light, its heat is intense ; it burns without any smoke. There are several substances which commu nicate colour to the flame of alcohol: boracic acid and salts of copper impart green, barytic salts yellow, and the salts of strontia an in tense and beautiful red colour. These pro perties are made available in pyrotechny or fire-works.
Alcohol combines in definite proportions with chloride of calcium, nitrate of magnesia, and other salts, with which it forms alcoates. It dissolves resins, essential oils, camphor, sugar, soap, and numerous acids, with readi ness; it also readily dissolves ammoniacal gas. As alcohol remains fluid at the lowest temperatures, it is advantageously employed in filling thermometer tubes, and in experi ments on artificial cold ; its antiseptic proper ties are great, and hence its use in preserving anatomical preparations ; on account of its ready inflammability, the purity, and the in tense heat of its flame, it is conveniently, but not economically employed in chemical lamps, usually termed spirit lamps. There are many other useful purposes to which this remark able liquid is applied ; but its chief employ ment is in the form of beverages.