Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 4, 1802).djvu/370

336] of such wine. Should, however, any matters accidentally remain, Dr. directs a little gum-arabic, or a few whites of eggs, to be added; after which the sand-shower is to be repeated, till the fluid become perfectly clear.

The  of wines is, in general, independent of their properties; being in many instances artificial, and imparted to those liquors, after they have come into mercantile hands. Thus, white wines are tinged red, by decoctions of logwood, the juices of elder and bilberries; in France, by the husks of tinged grapes; and, when a proper colouring matter is required, solutions of stick-lac, and turnsol, have been proposed as useful substitutes. There are, however, other ingredients frequently employed by unprincipled persons; and which produce deleterious effects on the human system. As it is of great importance to expose such adulterations, we shall communicate a few simple means, by which they may be discovered, both by the taste, and by the eye. Thus, if new white wine be of a sweetish flavour, and leave a certain astringency on the tongue; if it have an uncommonly high colour, which is at the same time disproportionate to its nominal age, and to its real strength; or, if it have an unusually pungent taste, resembling that of brandy, or other ardent spirits, such liquor is generally sophisticated.—Farther, when red wine presents either a very pale, or a very deep colour; or possesses a peculiarly tart and astringent taste; or deposits a thick crust on the side or bottoms of glass-vessels, it has then probably been coloured with some of the substances above mentioned; and which may be easily detected, by passing the liquor through filtering paper; when the tinging matters will remain on its surface. Such fraud may also be discovered, by filling a small phial with the suspected wine, and closing its mouth with the finger: the bottle is then to be inverted, and immersed into a bason containing pure water; when, on withdrawing the finger from its aperture, the tinging or adulterating matter will pass into the water, so that the former may be observed sinking to the bottom, by its greater weight.

Wines frequently become tart, and even sour, in consequence of the fermentation having been mismanaged; or, by keeping them in improper places; or from unforeseen accidents: in these cases, cyder, or the juice of carrots and turnips, is commonly mixed with the liquor, to overcome its acidity; but, as such juices do not always sweeten the wines to a sufficient degree, the latter are often adulterated with alum, or with sugar of lead; preparations, that cannot fail to be productive of the worst effects; as they doubtless are slowly operating poisons. Hence we deem it our duty to give an analytical account of the principal tests, or test-liquors, discovered by ingenious chemists; both for the health and satisfaction of our readers.

If wine be adulterated with , M. directs a small quantity of the suspected liquor to be mixed with a little lime-water: at the end of 10 or 12 hours, the compound must be filtered; and, if crystals are formed, it contains no alum: in the contrary case, the residuum, after filtration, will split into