BARYTA

(Greek, ficc^v;, heavy.) Ths oxide of barium, composed of 70 barium and 8 oxygen. Baryta is commonly called an alkaline earth. It is of a grey colour, diflficultly fusible, and poisonous. It is soluble in about 20 parts of cold water. It forms white salts with the acids, all of which are poisonous except the sulphate. The soluble salts of baryta are excellent tests of the presence of sulphuric acid, which they indicate in solution by a white precipitate, insoluble in water and in acids, and composed of 77 baryta and 40 sulphuric acid; 117 parts, therefore, of pure and dry sulphate of baryta are equivalent. to 40 of sulphuric acid. There are only two abundant natural compounds of baryta: the sulphate, which occurs crystalline, and the carbonate. Native sulphate of baryta, heavy spar, or baro-selenite, is found in this country in Cumber land and West more land; a variety from Derby shire is provincially called caiok. Native carbonate of baryta, or barolite, was first discovered at Angle sark in Lancashire by Dr. Withering, and hence called Witherlte. It occurs crystallised and ma ive. It consists of 77 baryta and 22 carbonic acid; its equivalent, therefore, is 99. [s. 148]