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 quantity of sample ✕ (degrees over or under proof + 100) divided by 100.

The presence of water in alcohol may be detected in several ways. Aqueous alcohol becomes turbid when mixed with benzene, carbon disulphide or paraffin oil; when added to a solution of barium oxide in absolute alcohol, a white precipitate of barium hydroxide is formed. A more delicate method consists in adding a very little anthraquinone and sodium amalgam; absolute alcohol gives a green coloration, but in the presence of minute traces of water a red coloration appears. Traces of ethyl alcohol in solutions are detected and estimated by oxidation to acetaldehyde, or by conversion into iodoform by warming with iodine and potassium hydroxide. An alternative method consists in converting it into ethyl benzoate by shaking with benzoyl chloride and caustic soda.

Alcohol is extensively employed as a solvent; in fact, this constitutes one of its most important industrial applications. It dissolves most organic compounds, resins, hydrocarbons, fatty acids and many metallic salts, sometimes forming, in the latter case, crystalline compounds in which the ethyl alcohol plays a rôle similar to that of water of crystallization. This fact was first noticed by T. Graham, and, although it was at first contradicted, its truth was subsequently confirmed. In general, gases dissolve 7 volumes of hydrogen, 25 volumes of oxygen and 16 volumes of nitrogen.

Potassium and sodium readily dissolve in ethyl alcohol with the production of alcoholates of the formula C2H5OK(Na). These are voluminous white powders. Sulphuric acid converts it into ethyl sulphuric acid (see ), and sulphur trioxide gives carbyl sulphate. The phosphorous haloids give the corresponding ethyl haloid. Ethyl chloride (from the phosphorus chlorides and alcohol) is an ethereal liquid boiling at 12·5° C., soluble in alcohol, but sparingly so in water. Oxidation of ethyl alcohol gives acetaldehyde and acetic acid. Chlorine oxidizes it to acetaldehyde, and under certain conditions (q.v.) is formed.

In almost all countries heavy taxes are levied on manufactured alcohol mainly as a source of revenue. In the United Kingdom the excise duty is eleven shillings per proof gallon of alcohol, while the customs duty is eleven shillings and fivepence; the magnitude of these imposts may be more readily understood when one remembers that the proof gallon costs only about sevenpence to manufacture. The great importance of alcohol in the arts has necessitated the introduction of a duty-free product which is suitable for most industrial purposes, and at the same time is perfectly unfit for beverages or internal application.

In the United Kingdom this “denaturized” alcohol is known as methylated spirit as a distinction from pure alcohol or “spirits of wine.” It was first enacted in 1855 that methylated spirit, a specific mixture of pure alcohol and wood-naphtha, should be duty-free; the present law is to be found in the Customs and Inland Revenue Act of 1890, and the Finance Act (sect. 8) of 1902. From 1858 to 1861 methylated spirit was duty-free when it was required for manufacturing processes, and the methylation or “denaturizing” was carried out in accordance with a prescribed process. During the next three decades (1861–1891) the law was extended, and methylated spirit was duty-free for all purposes except for use as beverages and internal medicinal applications. This spirit (“unmineralized methylated spirit”) consisted of 90 parts of alcohol of 60–66 over-proof (91–95% of pure alcohol) and 10 parts of wood-naphtha. It was found, however, that certain classes were addicted to drinking this mixture, and since 1891 the sale of such spirit has been confined to manufacturers who must purchase it in bulk from the “methylators.” For retail purposes the “ordinary” methylated spirit is mixed with ·357% of mineral naphtha, which has the effect of rendering it quite undrinkable. The Finance Act of 1902 allows a manufacturer to obtain a license which permits the use of duty-free alcohol, if he can show that such alcohol is absolutely essential for the success of his business, and that methylated spirit is unsuitable. Notwithstanding this permission there have been many agitations on the part of chemical manufacturers to obtain a less restricted use of absolute alcohol, and in 1905 an Industrial Alcohol Committee was appointed to receive evidence and report as to whether any modification of the present law was advisable. In the United States the same question was considered in 1896 by a Joint Select Committee on the use of alcohol in the manufactures and arts. Reference should be made to the reports of these committees for a full account of the use, manufacture and statistics of “denaturized” spirits in various European countries.

In Germany, the use of duty-free spirit is only allowed to state and municipal hospitals, and state scientific institutions, and for the manufacture of fulminates, fuzes and smokeless powders. The duty-free “denaturized” spirits may be divided into two groups—“completely denaturized” and “incompletely denaturized.” In the first category there are two varieties:—(1) A mixture of 100 litres of spirit and 2 litres of a mixture of 4 parts of wood-naphtha and 1 of pyridine bases; this spirit, the use of which is practically limited to heating and lighting purposes, may be mixed with 50 grs. of lavender or rosemary, in order to destroy the noxious odour of the pyridine bases. (2) a mixture of 100 litres of spirit, 1 litres of the naphtha-pyridine mixture described above, litre of methyl violet solution, and from 2 to 20 litres of benzol; this fluid is limited to combustion in motors and agricultural engines. The second category, or “incompletely denaturized” spirits, include numerous mixtures. The “general” mixture consists of 100 litres of spirit, and 5 litres of wood spirit or litre of pyridine. Of the “particular” varieties, we can only notice those used in the colour industry. These consist of 100 litres of spirit mixed with either 10 litres of sulphuric ether, or 1 litre of benzol, or litre of turpentine, or ·025 litre of animal oil.

The German regulations are apparently based on a keen appreciation of the fact that while one particular denaturizing agent may have little or no effect on one industry, yet it would be quite fatal to the success of another; there is consequently a great choice of denaturizing agents, and in certain cases it is sufficient to mix the alcohol with a reagent necessary for the purpose in hand, or even with a certain amount of the final product, it being only necessary to satisfy the state that the spirit is not available as a beverage.

In France, the general denaturizing agent is wood-spirit of at least 58 over-proof, and containing 25% of acetone and 2·5% of impurités pyrogenées; 10 litres of this spirit denaturizes 100 litres of alcohol. This mixture is supplied to manufactures and corresponds to the British unmineralized methylated spirit; but the regulations are more stringent. When sold for lighting and heating purposes, it is further admixed with 0·5% of heavy benzene boiling at 150°–200° C. Provisions are also made for special denaturizing processes as in Germany.

In America the internal revenue tax on denaturized alcohol (formerly duty-free only to scientific institutions) was removed by Congress in 1906 (act of June 7th).

Pharmacology, Toxicology and Therapeutics of Alcohol.—Alcohol is of great medicinal value as a solvent, being used to form solutions of alkaloids, resins, volatile oils, iodoform, &c. In strength of about 10% and upwards it is an antiseptic. If applied to the skin it rapidly evaporates, thereby cooling the skin and diminishing the amount of sweat excreted. This refrigerant and anhidrotic action is employed to soothe many forms of headache by bathing the forehead with eau de Cologne. If, on the other hand, the alcohol be rubbed into the skin, or if its evaporation be prevented—as by a watch-glass—it absorbs water from the tissues and thus hardens them.

Thoroughly rubbed into the skin alcohol dilates the blood-vessels and produces a mild counter-irritant effect. Many alcoholic liniments are therefore employed for the relief of pain, especially muscular pains, as in lumbago and other forms of so-called “muscular rheumatism.” Given internally in small quantities and in sufficient dilution, alcohol causes dilatation