Analyse des Vins

Abstract

ALTHOUGH wine is gradually becoming more and more important as an item in the national drinkbill-last year we imported 16,782,038 gallons, valued at,£5,995,133—its analysis and the methods for1 the detection of its sophistication have received comparatively little attention from the chemists of this country. On the other hand, in France and Germany the subject has been very thoroughly investigated in practically all its many details, and carefully worked-out methods have been prescribed for the guidance of the public analysts of those countries. Indeed, there is probably no article of food or drink, with the possible exception of milk, of which the chemistry has been so well thrashed out. Wine is in reality a highly complex fluid, and on account of the character of certain of its proximate constituents it is frequently liable to change. It contains various alcohols, glycerin, acids, salts, “extractive matter,” together with those principles which give to it its particular colour, special flavour, smell, or "bouquet."Whilst some of these constituents, can be accurately isolated and described, others can only be detected by the sense of smell. The principal alcohol is, of course, ethyl alcohol, but butyl and amyl alcohols, together with ethylene glycol and isobutyl glycol are not unfrequently present in greater or less quantity. The quantity of alcohol in natural wines may be said to vary from 6 to 12 per cent., and the quantity of glycerin from 7 to 10 per cent, of the alcohol present. Tartaric, malic, suc-cinic, glycollic, and oxalic, together with tannic and acetic, are the chief acids in wine. These are said to aid in its preservation, by preventing the formation of fungi. Traces of other fatty acids, such as propionic, butyric, and cenanthic acids are also present, as well as acetaldehyde, and possibly its homologues. Tartaric acid occurs mainly as the dextro variety: laevo-tartaric acid is only of comparatively infrequent occurrence. If tartaric acid is not found, as, for example, in certain samples of sherry, its absence is almost certainly due to its removal by “plastering.”The amount of free acid in sound wine, reckoned as tartaric acid, varies between 0˙3 and 0˙7 per cent.; a greater amount than this imparts sourness to the wine.

Analyse des Vins.

Par le Dr. L. Magnier de la Source. (Paris: Gauthier-Villars et Fils, 1892.)