Barium, Hydrate of

Ba(HO) 2 . Syn. Hydrate of baryta ; Barytæ hydras , L. Prep. By digesting caustic baryta, or barium oxide, with a little water, or igniting gently the crystallised hydrate. It can be obtained crystallised as follows: 1. From a concentrated solution of either nitrate or chloride of barium, precipitated with a rather strong solution of pure pota a, or of pure soda, perfectly free from carbonic acid. 2. A strong solution of sulphide of barium is boiled with succe ive portions of black oxide of copper, until it ceases to give a black precipitate with a salt of lead; the liquid, after filtration, yields crystals of the hydrate on cooling.