Felspar, ground

S. Peacock heated a mixture of powder felspar and coal in a reducing atm., and treated the product with superheated steam in an autoclave in order to recover the water-soluble potash. B. F. Halvorsen heats to 050° a mixture of ground felspar, cyanamide, and alkali salts with superheated steam. Ammonia and soluble potash are formed. H. W. Charlton digested greensand with lime and water in an autoclave. 

The saltpetre of commerce is derived principally from the East Indies, where, as also in Persia, Egypt, and Spain, it appears as an efflorescence on the surface of the soil. In some other countries, as the coast of the Adriatic, in Ceylon, North America, Africa, and Tene-riffe, it is found on the walls of natural caverns formed in limestone rocks, and which contain also felspar and magnesia. It is also found widely distributed in some parts of Hungary, but in no case extending to any great depth below the surface of the ground, nor even to such a depth as the air cannot penetrate. Its appearance on the surface of the ground is explained by its ready solubility in water, as when ite solution, in obedience to the law of capillary attraction, rises to the surface, the liquid is vaporized by the action of sun and air, and its place is immediately occupied by a fresh portion from below, which disappears in the same manner, until at last an incrustation of the salt is formed of considerable thickness, either in solid crystals, or as an effloresced mass. 

Porcelain Stoneware, containing plastic clay from the Palatinate and from Vallendar, with ground quartz and hono ashes. The glazo free from lead and composed of borax, alkali, and felspar. 

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