Barium, Oxide of. BaO. Syn. Baryta, Bary′tes, Cau′stic baryta*, Ox′ide of ba′′rium, Protox′ide of b., Heav′y earth; Baryte, Oxide de barium, Terre pesante†, &c., Fr.; Baryt, Baryterde, Schwererde, &c., Ger. One of the earths discovered by Scheele in 1774.
Sources. Sulphate and carbonate of barium are abundant minerals, forming the ‘vein-stone’ of many lead mines. It is from the
latter that baryta and the barium salts are almost exclusively obtained.
Prep. 1. A mixture of carbonate of barium and charcoal (both in fine powder and moistened) is strongly ignited, for some time, in a porcelain, Hessian, or black-lead crucible, and then allowed to cool out of contact with the air, from which it must also be subsequently carefully preserved.
2. (Pure.) Crystallised nitrate of barium is calcined in a capacious covered porcelain or Hessian crucible, at a bright red heat, until red (nitrous) vapours are no longer disengaged, even on raising the temperature; and the residuum, as soon as the temperature has fallen sufficiently, but whilst still warm, is at once transferred to a bottle, as before.
3. M. Rosenthiel’s process is founded upon the decomposition of sulphide of barium dissolved in boiling water by oxide of zinc. Caustic baryta and sulphate of zinc are formed.
Prop. A greyish-white, spongy, earthy-looking mass, fusible only before the oxyhydrogen blowpipe; highly caustic, corrosive, and alkaline, and slaking, like quick-lime, on the addition of water, but with the evolution of more heat.
Barium, Peroxide of. BaO2. Syn. Deutox′ide of barium; Ba′′rii binox′ydum, &c. L.; Binoxide de baryum, &c., Fr. Prep. Pure baryta is heated to full redness in a porcelain tube, and a stream of pure dry oxygen passed over it as long as the gas is absorbed.
Baryta, 4 parts, is heated as above in a platinum crucible, and chlorate of potassium, 1 part, gradually added to it; the chloride of potassium formed along with the binoxide being afterwards washed away with cold water.
Prop., &c. Grey or greyish-white; with water it forms a hydrate, which is slightly soluble in water, and undecomposed by it in the cold. It is interesting chiefly in its relations with peroxide of hydrogen and the oxygenised acids of M. Thénard.