C₂H₆O } C₂H₆O } Two of alcohol C₆C₆H₁₂O₆ = CO₂ } CO₂ } Two of carbonic acid. There are other fermentations allied to the vinous. Thus the =Acetous= fermentation results in the conversion of alcohol into vinegar, as in the souring of beer or wine. The =Lactic= fermentation leads to the conversion of milk-sugar into lactic acid, with consequent souring of the milk. =Alcohol=, or more correctly ethylic alcohol, is a colourless liquid, having a pleasant vinous odour, and evaporating rapidly on exposure to air. It burns with a bluish sootless flame, and is a capital solvent for resins and other substances. _Rectified spirit_ is absolute alcohol mixed with 16 per cent. of water. _Proof-spirit_ is a mixture of 42·7 per cent. by volume of absolute alcohol, and 57·3 per cent. of water. Thus the ratio of alcohol to proof-spirit being as 1: 1·76, the amount of alcohol in any liquid being given, the amount of proof-spirit can readily be calculated. The fermented drinks containing alcohol may be classed as (1) malt liquors, (2) wines, and (3) distilled spirits. The relative properties of these will be considered afterwards; in the next two sections will be considered the effects of diluted alcohol in whatever form it is taken. =Effects of Moderate Doses of Alcohol on the System.=—In studying the physiological effects of alcohol, one has to guard against the fallacy that these are the same, only differing in degree, whatever the dose may be. The effects of large doses of alcohol are almost exactly the reverse of those produced by small doses. It will be necessary to define, therefore, what we mean by a moderate dose. By a moderate dose, we understand the amount of alcohol which can be taken without any alcohol being eliminated in the urine. Dr. Anstie found that 1½ ounces, that is three tablespoonsful, of absolute alcohol, taken in twenty-four hours, caused its appearance in the urine; and Dr. Parkes and Count Wollowicz obtained almost precisely the same result. Anything below some quantity between 1 and 1½ fluid ounces per day can be disposed of in the system, and is probably oxidised like ordinary foods. The amount of alcohol, in the form of alcoholic beverages, corresponding to this =maximum dose= of absolute alcohol is approximately as follows:— One imperial pint (20 fluid ounces) of bottled beer (5 per cent. of alcohol). One tumblerful (10 „ „ ){of claret, hock, and} {other weaker wines } (10 „ „ ). 2½ glasses (5 „ „ ){of port, sherry, and} {other strong wines } (20 „ „ ). One glass (2 „ „ )of brandy or whiskey (50 „ „ ).