Tartaric Acid

(-tar'ik.) (Chem.) An organic acid widely diffused in the vegetable kingdom, especially in grape juice, in which it occurs as acid tartrate of pota ium. There are 5 different T. A. known to chemists, which all po e the same composition (2HO.C8H1010), and scarcely differ from one another except in their action on polarized light, and in crystalline form. T. A. forms numerous double salts. The following are the more important tart rates: - Bi-tartrate of Pota ium, or cream of tartar (KO.CgH5011), is difficultly soluble in water, and separates from its hot solutions in small tri metric crystals. In the crude state it is called Argol, or Tartar, and is deposited from many kinds of wine on keeping. It unites with soda to form a double salt, which crystallizes in large rhombic prisms, readily soluble in water. It is sometimes called Rochelle salt. Pota io Antimonious Tartrate is of considerable use in medicine, under the name of tartar-emetic, and it crystallizes in octahedrons, which are tolerably soluble in water. [s. 879]