C2H2OH2CO2H2

Tartaric Tar*tar"ic, a. (Chem.) Of or pertaining to tartar; derived from, or resembling, tartar. [1913 Webster]

{Tartaric acid}. (a) An acid widely diffused throughout the vegetable kingdom, as in grapes, mountain-ash berries, etc., and obtained from tartar as a white crystalline substance, {C2H2(OH)2.(CO2H)2}, having a strong pure acid taste. It is used in medicine, in dyeing, calico printing, photography, etc., and also as a substitute for lemon juice. Called also {dextro-tartaric acid}. (b) By extension, any one of the series of isomeric acids (racemic acid, levotartaric acid, inactive tartaric acid) of which tartaric acid proper is the type. [1913 Webster]