ALCOHOL 265 taken place; another evidence of which is con- densation and diminution of bulk, and greater specific gravity. The greatest heat and con- densation result from a mixture of 52-3 per cent, of alcohol and 47*7 of water, the volume after condensation being equal to 96-35. The specific gravity, therefore, of such mixtures can only be determined by experiment. Diluted with water, alcohol acts as a stimulant, exciting par- ticularly the nervous and vascular systems. In large doses it produces intoxication, and when taken pure acts as a narcotic poison, producing death. It is very inflammable, burning with a pale bluish flame without smoke. The pro- ducts of its combustion are carbonic acid and water. Absolute alcohol boils at 173 F. The specific gravity of its vapor is 1-6133. Under the exhausted receiver of an air pump it boils at common temperatures. No degree of cold ever yet obtained has effected its congelation. Faraday exposed it to a temperature of 166 F. below zero, which caused it to thicken consid- erably. It is thus well suited for thermome- ters for measuring low temperatures. Alcohol is employed in medicine as a solvent in the preparation of tinctures. It is also a solvent of resins, gums, &c. "With the former it makes varnishes ; with essential oil, perfumed spirits. The ethers are preparations of it in combination with an acid. It is used with spirits of turpen- tine to make camphene and the various other illuminating fluids of this class. It is used to preserve anatomical preparations, its effect be- ing to combine with the moisture, and so pre- vent this from acting upon the animal substance to produce decay. To the chemist it is valua- ble as a convenient fuel, producing in his lamp much heat with no annoyance from smoke ; and it is of frequent use as a reagent for separating salts, one of which is soluble and the other in- soluble in it. The quantity of alcohol in wine, beer, and other fermented liquors, is very vari- able. Prof. Brande found from 1 to 2 per cent, only in small beer ; 4 in porter ; from 6 to 9 in ales ; about 12 in the light wines of France and Germany ; from 19 to 25 in port, sherry, and other strong wines ; and from 40 to 50 per cent., and occasionally more, in brandy, gin, and whiskey. The strength of these liquors is as- certained by various expedients ; but the pro- cess is sometimes complicated by reason of the different ingredients intermixed to color, sweet- en, or flavor the liquor, or fraudulently added to alter the specific gravity, or to substitute a cheaper material. Mixtures thus complicated require to be first distilled, before their strength can be ascertained by the usual process of spe- cific gravity. Common modes of judging of the strength are by tasting, observing the size and appearance of the bubbles when shaken, the sulking or floating of olive oil in them, and the appearances they exhibit when burned. If cotton or gunpowder immersed in them is in- flamed by their combustion, the spirit is con- sidered pure. Alcohol is decomposed by pass- ing through a red-hot glass or porcelain tube, into carbonic acid, water, hydrogen, olefiant gas, marsh gas, naphthaline, empyreumatic oil, and charcoal. By electrolysis, on adding potash, hydrogen is given off at the negative pole and aldehyde resin is formed at the positive pole. The product of its combustion in the air is car- bonic acid and water. The vapor of alcohol mixed with air explodes by contact with flame or an electric spark. On contact with platinum black it is imperfectly oxidized, forming car- bonic acid, water, aldehyde, acetic acid, formic acid, acetal, and a peculiar compound with an excessively pungent odor. Chlorine gas con- verts alcohol into aldehyde, chloral, chloride of ethyl, and acetate of ethyl. One of these products, chloral, has recently been introduced as a valuable hypnotic medicine. Concentrated chloric acid ignites alcohol; dilute, forms acetic acid. Alcohol unites in definite propor- tions with several salts, forming crystallizable compounds in which it plays a part analogous to the water of crystallization. The methyl- ated spirit of commerce consists of a mixture of alcohol of specific gravity 0-830 with 10 per cent, of common wood spirit. This addition of wood spirit scarcely interferes with the em- ployment of the spirit as a solvent, though it renders it unfit for use afterward as a stimu- lant drink. Alcohol or spirit of wine is the most important member of a group of com- pounds which manifest a close analogy with each other, both in chemical composition and in the decompositions of which they are suscep- tible. The general doctrine of alcohols was in- troduced into science by MM. Dumas and Peli- got. These illustrious chemists, in the course of their investigations into the properties of wood spirit, discovered that vinic alcohol was not a unique body, but that in wood spirit was to . be found a compound of similar character, which they therefore called methylic alcohol. Subsequently a long list of bodies properly classed under the generic term of alcohols was discovered by European chemists. As these bodies were found to be closely related to each other and to differ by a common multiple CH a , they were said to be homologous, be- cause a like description is applicable to each member of the series. The following table in- cludes the most important homologous alcohols: Methylic alcohol CH.O Ethvtic " C, II, O or CH 4 f (CH.,) Propvlic " C 3 III O or CH 4 O + 2(CH 3 ) E5y if " i C II or CH O 4- 3(CII 2 ) Amylic " C 5 II 12 or CII 4 O -t- 4(C1U Caproic " Ce H^O or CII 4 O+- wCHj) Caprylic " C 8 II 18 O or C1I 4 O+ 7(C1I 3 ) Cetvlic " ... C 1 gH S4 O or CII 4 O+15(CH 2 ) Cervlic " '.'.'.'. C a7 H 68 O or CH 4 O + 2(WCII,)) Melyssylic C 80 H. a O or CH 4 0+29(CII,) ALCONA, a K E. county of Michigan, on Lake Huron; area, 630 sq. m.; pop. in 1870, 696. It is drained by the Ausable and one of its branches. Alcona lake, in the K part, emp- ties through Thunder Bay river into Thunder bay. In 1870 there were three schools attend- ed by 137 children.
