Uses, Phys. eff., &c. In chemistry, it is employed as a test for sulphuric acid and the soluble sulphates. In medicine, it has been employed, both internally and externally, as an alterative, resolvent, and deobstruent, in scrofula, glandular swellings, and enlargements,
scirrhous cancer, skin diseases, &c.; and more particularly in the first with marked benefit. In large doses it is poisonous. According to Sir B. Brodie, its action on animals is analogous to that of arsenic. Locally, it acts as an irritant. A very weak solution, used as a lotion, often proves serviceable in herpetic eruptions, and as a collyrium in scrofulous ophthalmia. Dose, 1⁄2 gr. thrice a day, in water, gradually increased to 2 or 3 gr.
Barium, Chlorate of. Ba(ClO3)2. Syn. Chlorate of bary′ta; Bary′tæ chlo′′ras, L. Prep. From a solution of chloric acid neutralised with freshly precipitated carbonate of barium; the resulting solution, after filtration, being crystallised by evaporation.
By passing chlorine through strong milk of hydrate or of carbonate of barium, in the same way as in making chlorate of potassium.
Prop., &c. Soluble in 4 parts of cold water. Used in pyrotechny, and to make chloric acid.
Barium, Ferrocy′anide of. Ba2FeC6N6. Syn. Ba′′rii ferrocyani′dum, L. From pure ferrocyanide of iron digested in baryta water. By careful evaporation, efflorescent prismatic crystals may be obtained, soluble in 41⁄2 parts of water.
Barium, Fluoride of. BaF2. Syn. Ba′′rii fluori′dum, &c., L. A white powder, formed by digesting freshly precipitated carbonate of barium in hydrofluoric acid, in excess.
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 potassa, or of pure soda, perfectly free from carbonic acid.
2. A strong solution of sulphide of barium is boiled with successive 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.