Mag-nē'si-ā, n.

(-nē'zhi-ā, or -nē'zha) (Synop. § 130), n. [N. Lat. magnesia, from Gr. λίθος Μαγνήτιδος, the magnet, also a mineral that looked like silver, a kind of talc; It. & Sp. magnesia, Fr. magnésie. Cf. MAGNET.] (Chem.) An earth; the oxide of magnesium. It occurs in nature as periclase.

Carbonate of magnesia (Med.), a white pulverulent earth, used as a mild cathartic. Calcined magnesia is the burnt carbonate.—Sulphate of magnesia, Epsom salts.