Prep. An ounce of chloride of barium, in crystals, is dissolved first in eight fluid ounces of water, and sufficient water then added to make the solution measure ten fluid ounces.

Use. Chloride of barium forms with sulphuric acid and the soluble sulphates a white precipitate of sulphate of baryta, a very insoluble compound, scarcely acted upon even by boiling nitric acid. The solution of chloride of barium is used as a test for sulphuric acid and the sulphates, and for this purpose is applied to nearly all the inorganic substances in the list of the Materia Medica, and also to some of the organic.