ALCOHOL. Origin of the word some what obscure. According to most authorities it is from the Arabic al-kohq, kok'l being the finely-powdered black sulphide of antimony used in the East for painting the eyebrows. First used to signify this powder, it afterward stood for any fine powder obtained by trituration or sublimation; then for any essence or spirit, and lastly for the liquid to which it is now applied. In the latter part of the 16th century spirit dried over powdered carbonate of potash was called spiritus alcolisatus; but Kopp suggests that this is a corruption of spiritus alcalisatus, signifying spirit that has been treated with alkali, and that alcolized (or alcoholized) spirit was then shortened to alcohol.
1. Ethyl Alcohol.— Unless otherwise quali fied, °alcohol" is understood to mean the liquid known to the chemist as °ethyl alcohol," and to the trade as alcohol," or °spirits of wine." It is colorless and inflammable, burning with a flame that is intensely hot but almost non-luminous. Most of the alcohol used in the arts is produced by the fermentation of sugars or starches. A thin paste is made from mo lasses, finely ground corn or potatoes or other natural products containing sugars or starches, and a small quantity of malt or other agent con taining diastase (q.v.) is added. The mixture is then allowed to stand until the diastase has transformed the starch into dextrose (glucose). Taking the chemical formula of starch as (CHnOe), for the sake of illustration, we may have either of the following reactions as the primary effect of the diastase: (C.11.001). + H20 = + Celina Starch Water Dextrin Dextrose (Celina), + 2H30 = CuHnOn C41-1120.
Starch Water Maltose Dextrose Neither dextrin nor maltose is directly ferment able, but each slowly becomes further trans formed into dextrose, as appears from the following equations: Dextrin Water Dextrose CulinOn He0=2C01-1120. • Maltose Water Dextrose The reduction to dextrose (glucose) being now complete, yeast is added, and the temperature is maintained at from 72° to 85° F. Under the influence of the yeast-plant (Saccharomyces cerevisie or Torula cerevisur) the dextrose then undergoes fermentation, alcohol and car bon-dioxide being the chief products, according to the equation': Celina = 2C,1-1.0 2C01 Dextrose Alcohol Carbon dioxide A certain amount of nitrogenous and mineral matter must be present, in addition to the starch and sugar, in order to furnish food for the yeast-plant. The next step in the process is to distil off the alcohol from the fermented product. This is usually done in a still heated by steam. One or more redistillations may be necessary in order to obtain the alcohol in a satisfactory state of purity and strength. The product of the original fermentation is weak in alcohol, but the subsequent distillations effect a great concentration, since alcohol is far more volatile than water and therefore passes off first. The British Pharmacopoeia requires recti fied spirits (produced as described above) to have a specific gravity of 0.838, which is equiv alent to 84 per cent of alcohol by weight. The United States Pharmacopoeia fixes the specific gravity at 0.820, which corresponds to 91 per cent of alcohol by weight. It is possible to ob tain this latter degree of concentration by ordinary distillation; but it is not possible to free the alcohol entirely from water without distilling it with potassium-carbonate, quick lime, calcium-chloride or some similar sub stance possessing sufficient affinity for water to prevent the water from passing over. The best way to eliminate the last traces of water is to digest strong alcohol with quicklime for two hours at about F., and then distil, rejecting the first and last portions of the distillate. The product is then subjected to the same treatment a second time, after which it will probably be free from water. Alcohol thus deprived of the last trace of water is termed °absolute or °anhydrous" alcohol. Its chemical formula is lie.OH, and its specific gravity is 0.80625 at 32° F., and 0.79367 at 59° F. Absolute alcohol boils at 173.1° F., when the barometer stands at 29.92 inches (760 mm.). It freezes at about 200° below zero F., first becoming very viscid. Its low freezing-point has led to its use as a thermometric fluid for the measurement of low temperatures. Its specific heat is variously
estimated, but is in the vicinity of 0.61. Abso lute alcohol has a powerful affinity for water, and it is therefore used as an astringent, and (for certain purposes) as an antiseptic. When exposed to the air it quickly absorbs a sensible amount of aqueous vapor, and ceases to be °absolute." According to the experiments of Atwater, the human body is capable of oxidiz ing about two ounces of it per day, since this amount can be administered without any evi dence of alcohol appearing in the excreta. Alcohol mixes with water in all proportions, and is extensively used as a solvent for sub stances that do not dissolve in water: notably for organic substances and for alkaloids and drugs. When absolute alcohol is mixed with water the volume of the mixture is consider ably less than the sum of the volumes of the constituents. The specific gravity of such a mixture therefore cannot be deduced by any simple formula; but it has been found by direct experiment, and tabulated, for all possible mix tures and temperatures. The strength of a given mixture of alcohol and water may be found by observing the specific gravity of the mixture at a definite temperature by means of a hydrometer (q.v.) and then referring to the tables. The greatest contraction of volume observed upon mixing absolute alcohol and water occurs when 49.8 volumes of water are mixed with 53.9 volumes of absolute alcohol, both liquids being at 32° F. The volume of the mixture is then 100, instead of 103.7, as it would be if there were no contraction. Men deleeff points out that this particular mixture corresponds to a possible compound having the formula C,H2O.3H2O; but it has not been con clusively proved that such compound exists. An alcohol containing 49.3 per cent (by weight) of absolute alcohol is known in the arts and for excise purposes as °proof spirit." This term was originally intended to denote alcohol just strong enough to ignite gunpowder when burned upon it; but it was defined by law in the reign of George III of England to be spirit such as shall, at the temperature of 51° F., weigh exactly twelve-thirteenth parts of an equal amount of distilled water" (Watts). At 60° F. proof spirit has a specific gravity of 0.920. A mixture stronger or weaker than this is said to be (respectively) overproof or under proof. Distilled liquors, such as whisky, brandy and gin, contain from 40 to 50 per cent of absolute alcohol, wines from 7 to 20, ale and porter from 5 to 7, and beer from 2 to 10. Alcohol coagulates albumen, and, partly for this reason and partly because of its action in arresting the development of micro-organisms, it prevents the putrefaction of dead animal matter. The alkali metals attack absolute alcohol rapidly with the formation of com pounds variously known as alcoholates, alco hates and alcoates, but more definitely and correctly as uethylates.'l Thus alcohol may be regarded as water in which one atom of hy drogen has been replaced by a molecule of the organic radical ethyl, C2H., and, water being H-O-H, the formula for alcohol may be written (C2115)-0-H. An alkali metal, when it com bines with alcohol, merely replaces the H at the right of this formula; and sodium ethylate (for example) is therefore (C2H0-0-Na, or simply C31-160Na. The commonest test for alcohol in small quantities consists in warming the suspected liquid (or its distillate) with caustic potash and iodine. If alcohol is present iodoform comes down after a time as a pre cipitate. In England. the use of alcohol in the arts is permitted without the payment of an excise tax, provided the alcohol contains 10 per cent of methyl alcohol (wood spirit). Alco hol so treated is known as "methylated spirit,' it is unfit for drinking and the methyl alcohol that it contains cannot be readily removed. Alcohol can be prepared directly from its ele ments as follows: Acetylene (q.v.), GH2, will combine directly with'hydrogen to form olefiant gas, GEL ; concentrated sulphuric acid will absorb olefiant gas with the formation of hydrogen-ethyl-sulphate, C2116.HSO4; and if the product so obtained is diluted with water and boiled, alcohol is formed in accordance with the equation :