Bittern, BITTER LIQUID, or SALT OIL,

Bittern, BITTER LIQUID, or SALT OIL, is an oily liquid obtained during the preparation of common Salt (q.v.). When the mother-liquor of the evaporating pans ceases to deposit crystals of common salt, there is left behind in the boilers the material called bittern. It consists principally of a strong solution of common salt, along with the chlorides of magnesium and calcium, to which the bitter taste is due; but it also contains the bromides of sodium and calcium, which are valuable sources of the element Bromine (q.v.). The bittern obtained from the salt-works at Epsom was at one time the source of the sulphate of magnesium (hence called Epsom salts), but at present this salt is obtained in other ways.