WINE. See FERMENTATION, &Z. All ; wines contain an acid, alcohol, tartar, ex tract, aroma, and a colouring matter. The presence and nature of each of these t principles may be ascertained in the fol lowing way. 1. Acid. All wines, even the softest and mildest, redden litmus, and therefore contain an acid. This abounds, however, chiefly in the thin wines of wet and cold climates, where the grape juice or must contains but a small portion of sugar. When wine has been boiled to extract the brandy, the liquor that re mains in the still, and is thrown away as useless, is a sour nauseous fluid, with an acrid and burnt flavour. When filtered and allowed to remain at rest for a time, it deposits a good deal of extractive mat ter, becomes covered with mould, and then contains a notable quantity of ace tons acid, which may be separated by distillation. The acid is, however, not en tirely acetous, at least not till after stand ing a considerable time, for it precipitates and forms an insoluble salt with lime water, and with the soluble salts of sil ver, lead, and mercury, and appears to be the malic acid mixed with a little ci tric, both of which are converted into vi negar by spontaneous decomposition. The wines that contain the greatest quan tity of these acids yield the worst brandy, nor is there any method yet known of se parating or neutralizing the acid without materially injuring the quality, or lessen ing the quantity of the ardent spirit. 2.
Alcohol. The existence of this principle and mode of extraction by distillation has been fully described under the article brandy. The quantity of alcohol varies prodigiously. The strong, rich, full-bo. died wines of the warmer vine countries will yield as much as a third of ardent spirit ; whilst the thin light wines will often give no more than about one-six teenth of the same strength. 3. Tartar.
This substance has also been fully de scribed in its proper place. Tartar is not altogether a product of the fermen tation of wine, since it is contained in must, though in small quantity. 4. Ex tract. Must contains an abundance of extractive matter, which materially as sists the fermentation, and is afterwards found, in part at least, in the lees, but another portion may be obtained from the wine by evaporation. It is also extract that mixes with and colours the tartar. By age the quantity of extractive matter diminishes. 5. Aroma. All wines pos. sess a peculiar and grateful smell, which would indicate a distinct aromatic princi ple, but it has never been exhibited in the form of essential oil, or condensed in any smaller quantity by distillation or any other mode. To give wine alt its aroma it should be fermented very slowly. 6. Colouring matter. The husk of the red grape contains a good deal of colour, which is extracted when the entire fruit is pressed, and becomes dissolved in the wine when the fermentation is complete. Many substances will separate the co lour. If lime-water is added to high-co loured wine, a precipitate is formed of ma lat of lime that carries down with it all the colouring matter, which cannot again be separated either by water or alcohol. But if wine alone is evaporated gently to dryness, and the residue treated with al cohol, the colouring matter dissolves therein. 1Ve may add too, that the na tural colour of wine is entirely and speed ily destroyed by the addition of hot well-burnt charcoal in pretty fine pow der. The colour of red wine in the state in which we receive it is not entirely that of the grape, but is given by other co louring substances, which, however, are quite innoxious.