Magnesia (?; 277), n. [L. Magnesia, fem. of Magnesius of the country Magnesia, Gr. h Magnhsia liqos a magnet. Cf. Magnet.] (Chem.) A light earthy white substance, consisting of magnesium oxide (MgO), and obtained by heating magnesium hydrate or carbonate, or by burning magnesium. It has a slightly alkaline reaction, and is used in medicine as a mild antacid laxative. See Magnesium.
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Magnesia alba [L.] (Med. Chem.), a bulky white amorphous substance, consisting of a hydrous basic carbonate of magnesium, and used as a mild cathartic.
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