Note: Do not rely on this information. It is very old.
Tartar Emetic is a salt of tartaric acid, C4H6O6, in which one atom of hydrogen is replaced by potassium and another by oxide-radical of antimony (SbO). It thus possesses the formula C4H4O6K (SbO). It is easily soluble in boiling water, and considerably less so in cold water. It crystallises in shining rhombic forms of composition 2C4H4O7KSb + OH2, but the crystals on exposure lose their water of crystallisation and fall to a white powder. It is prepared by boiling antimony oxide with water and cream of tartar. Its solution has a peculiar taste, and the componnd is used to an extent medicinally as an emetic and sudorific, [TARTARIC ACID.]