ALCOHOL (Ar. al, the + kohl, exceedingly fine powder of antimony for painting eyebrows; hence the quintessence of something; finally rectified spirits, alcohol), or ALCO HOL, CAOH, often called spirits of wine. A chemical compound of carbon, hydrogen, and oxygen that has been known and ex tensively used from the earliest times. It is eonsumed in very large quantities in the form of intoxicating liquors, and is used for various purposes in the arts and manufactures. The alcohol of eommerce, in its various foams, is all made by fermentation. Natural products con taining a large amount of starch, such as grain, rice, potatoes, etc.. are reduced with water to a paste, and a small quantity of malt is added to produce fermentation, by which the starch is in a short time transformed into dextrin and a kind of sugar called maltose, according to the following chemical equation: 11,0 = Starch Dextrin Maltose Then yeast, which consists of living plant cells, is added to set up a new process of fermentation, by which the maltose is converted into alcohol, according to the following chemical equation: = + Maltose Alcohol The manufacture of alcohol thus involves two distinct processes of fermentation; for neither can alcohol be obtained from maltose by the ac tion of the diastase of malt, nor can maltose be obtained from starch by the action of yeast. Small quantities of organic substances are usually produced along with ethyl alcohol during fer mentation; one of these is the well-known fusel oil, a mixture of alcohols chemically allied to ordinary alcohol and containing mainly amyl alcohol. A small quantity of fusel oil is eon tabled even in the "raw spirit." a strong alcohol obtained by distilling the weak so lution obtained through fermentation. To free the raw spirit from fusel oil, which is highly injurious, it is mixed with water, filtered through charcoal. and subjected to a process of fractional distillation, the intermediate fractions, called rectified spirit, being practically free from fusel oil. The presence of the latter in spirit uous liquors may he readily detected by adding a few drops of eolorless aniline and two or three drops of sulphuric acid, a deep-red coloration being produced ht the presence of fusel oil. The flavor of alcoholic beverages is due to the pres ence of various organic substances often produced by modifying the process of manufacture. Thus both the flavor and color of beer depend largely on the temperature and duration of heat ing of the malt before using it ; the flavor of Scotch whisky is derived mainly from the peat used in drying the malt, etc. The quantity of al cohol contained in various beverages is very dif ferent: gin, rum, and the strong liquors contain from 40 to 50 per cent, of alcohol; port. contains from 15 to 25 per cent.; sherry or madeira, from 15 to 20 per cent.: champagne and burgundy, from 10 to 13 per cent.: hock, from 10 to 12 per cent.; claret, from S to 12 per cent.; cider and strong ale, 5 to 0 per cent.: beer or porter, from 2 to 5 per cent.; komniss, from I to 3 per cent. The United States Pharniacoptria fixes the specific gravity of rectified spirit at. 0.820, which corresponds to 91 per cent. of absolute al
cohol. The amount of alcohol in spirituous liq uids is estimated by observing their specific gravity; but as they usually contain other sub stances besides water, they must be distilled lie fore a determination can he made. Alcohol in its various forms, especially if taken habitually, is highly injurious to health. While it promotes very powerfully the secretion of the gastric juice, it sets up inflammation of the gastric walls and gradually produces chronic dyspepsia. (See ALCOHOL, PHYSIOLOGICAL AND ACTION OF.) The effects of chronic alcohol poisoning are described in the article ALconousm (q.v.).
Alcohol cannot be entirely freed from water by distillation. Anhydrous, or absolute alcohol, may be prepared by boiling strong commercial alcohol with unslaked lime until a small sample is turned yellow by barium oxide; to remove the last traces of water the alcohol thus obtained may be further treated with anhydrous copper sulphate and finally distilled over a small quan tity of metallic sodium. The presence of traces of water may be readily detected by the use of dehydrated copper sulphate, which remains white only in perfectly anhydrous alcohol. Absolute alcohol acts as a deadly poison. It is a colorless liquid of specific gravity 0.8062 at 0'; it boils at 78° and solidifies at about 130° below zero C. It is extremely hygroseopic and mixes in all proportions with water, ether, chloro form, carbon disulphide. and many other liquids. It. is also an excellent solvent for many substances, such as fats, oils, gums, resins. and a number of inorganic and is thus largely employed in the preparation of tinctures, varnishes, dyes, perfumes. etc. The presence of alcohol in aqueous solutions is best detected by the so-called iodofo•m reaction: small quantities of iodine and of potash almost immediately produce in the presence of alcohol a precipitate of iodoform, which may be readily recognized by its odor. In this manner i1. has been demon strated that minute quantities of alcohol are present in the soil. in water, and in the atmos phere. Small quantities of alcohol have likewise been found in the urine in diabetes. 'When acted on by an excess of dry chlorine gas, alcohol is transformed into chloral, from which, by the ac tion of alkali, very pure chloroform may be ob tained; chloroform may also be prepared from al cohol directly by the action of bleaching powder (chloride of lime). When warmed with concen trated sulphuric acid, alcohol yields ordinary ether. Alcohol is thus extensively employed in the manufacture of chloral. chloroform, and ether.
Aqueous alcohol was separated by distilla tion from the mixture obtained through fermen tation in the Middle Ages. Lowitz was the first to prepare anhydrous alcohol in 179G. The com position of alcohol was first determined by Sans sure in 1808.
Consult: Stevenson, A Treatise on A/cohoi, Irith Table's of Specific Hra•itics (London, 1888) ; Alaereker, Handbuch der Spiritusfabri kut ion (Berlin, 1889; French translation. two volumes, Lille, 1889) : and Roux's series of seven hooks on the manufacture of alcoholic beverages, published under the general title La fabrication de I'alcool (Paris, 1885-92). See ACETYLENE.