Emily Dickinson Lexicon

BIT'TERN, n. [from bitter.]

In salt works, the brine remaining after the salt is concreted. This being laded off, and the salt taken out of the pan, is returned, and being again boiled, yields more salt. It is used in the preparation of Epsom salt, the sulphate of magnesia, and of Glauber's salt, the sulphate of soda. – Johnson. Encyc.