tartar emetic, poisonous, odorless, transparent rhombic crystals or white powder with a metallic, sweetish taste. Chemically, it is potassium antimony tartrate, KSbC₄H₄O₇·1/2H₂O. It is used as a mordant in dyeing. Medically, it was formerly used as an emetic and expectorant, to produce sweating, and in the treatment of several diseases, but had frequent toxic side effects.

emetic, substance that produces vomiting. Direct, or gastric, emetics, which act directly on the stomach, include syrup of ipecac, sulfate of zinc or copper, alum, ammonium carbonate, mustard in water, or copious quantities of warm saltwater. Indirect, or systemic, emetics, such as apomorphine, induce vomiting by acting indirectly through the blood on the brain center that controls vomiting. Emetics are not used to treat poisoning by strong acids or alkalis, petroleum distillates such as kerosene, or substances causing convulsions.