Tartar, a concrete saline matter, which separates from wines, after they have undergone complete fermentation: it adheres to the top and sides of the cask, in red or whitish-grey crystals, according to the colour of the liquor. In this state, it is called crude tartar ; having a sub-acid taste, and being with difficulty soluble in water.

By repeated solution, filtration, and crystallization, crude tartar may be depurated or divested of all gross and impure particles, when it is called crystals of tartar; and, if these be reduced to powder, cream of tartar.

This salt is a mild, cooling and aperient medicine : if half or a whole ounce of it be taken in substance, with treacle, or any other vehicle, it proves an effectual purgative. Farther, when dissolved in water, it affords, with the addition of sugar, an agreeable acidulated drink, which is of great service in ardent fevers ; and likewise forms a pleasant beverage during the summer.

Tartar-emetic, or Tartaric Antimony, is prepared, according to the London College, by boiling in a glass vessel, 3 oz. of crocus of antimony, and 4 oz. of crystals of tartar, in 2 pints of distilled water, for about 15 minutes; when the solution should be filtred through paper, and the strained liquor kept in a cool place, in order to form crystals. - This preparation is employed as an emetic, for which purpose it is far superior to any other composition of antimony ; as it operates powerfully, without disordering the constitution. When the full effect of an emetic is required, the dose varies from 2 to 4 grains; though it may be more advantageously administered in smaller quantities, as a nauseating and sudorific medicine. - Dr. Hufeland has observed, that one scruple of starch, combined with a single grain of emetic tartar, operates with greater speed, and certainty, than a full dose of the latter.