1911 Encyclopædia Britannica/Bittern (brine)

BITTERN (from “bitter”), the mother liquor obtained from sea-water or brines after the separation of the sodium chloride (common salt) by crystallization. It contains various magnesium salts (sulphate, chloride, bromide and iodide) and is employed commercially for the manufacture of Epsom salts (magnesium sulphate) and bromine. The same term is applied to a mixture of quassia, iron sulphate, cocculus indicus, liquorice, &c., used in adulterating beer.