magnesia

n. [ L. Magnesia, fem. of Magnesius of the country Magnesia, Gr. h` Magnhsi`a li`qos 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. [ 1913 Webster ]

Magnesia alba [ L. ] (Med. Chem.), a bulky white amorphous substance, consisting of a hydrous basic carbonate of magnesium, and used as a mild cathartic. [ 1913 Webster ]