Magnesium

Mag·ne′si·um (măg·nē′zhĭ·ŭm or ·shĭ·ŭm), n. [NL. & F. See Magnesia.] (Chem.) A light silver-white metallic element, malleable and ductile, quite permanent in dry air but tarnishing in moist air. It burns, forming (the oxide) magnesia, with the production of a blinding light (the so-called magnesium light) which is used in signaling, in pyrotechny, or in photography where a strong actinic illuminant is required. Its compounds occur abundantly, as in dolomite, talc, meerschaum, etc. Symbol Mg. Atomic weight, 24.4. Specific gravity, 1.75.

Magnesium sulphate. (Chem.) Same as Epsom salts.