Calomel

Cal″o‐mel (kăl″ō̍‐mĕl), n. [Gr. καλόσ beautiful + μέλασ black. So called from its being white, though made from a black mixture of mercury and corrosive sublimate. Cf. F. calomélas.] (Chem.) Mild chloride of mercury, Hg2Cl2, a heavy, white or yellowish white substance, insoluble and tasteless, much used in medicine as a mercurial and purgative; mercurous chloride. It occurs native as the mineral horn quicksilver.