NITER, or SALTPETER, as it is frequently called; is the'nitrate of potash It usually occurs in long, colorless, striated, six-sided prisms; its taste is cooling, and very saline; it is soluble in seven times its weight of water at and in less than one third of its weight of boiling water, but is insoluble in alcohol. When heated to about it fuses without decomposition into a thin liquid, which, when cast in moulds, solidifies into a white, fibrous, translucent mass, known as sal prunelle. At a higher temperature, part of the oxygen is evolved, and nitrate of potash is formed. Owing to the facility with which niter parts with its oxygen, it is much employed as an oxidizing agent. Mixtures of niter and carbon, or of niter and sulphur, or of niter, carbon, and sulphur, deflagrate on the application of heat with great energy; and if niter be thrown on glowing coals, it produces a brisk scintillation. Touch-paper is formed by dipping paper in a solution of niter and drying it.
Niter occurs as a natural product in the East Indies, Egypt, Persia. where it is found sometimes as an efflorescence upon the soil, and sometimes disseminated through its upper stratum. The crude salt is obtained by lixiviating the soil, and allowing the solu tion to crystallize. A large quantity of niter is artificially formed in many countries of Europe, by imitating the conditions under which it is naturally produced. The most
eslential of these conditions seem to be the presence of decaying organic matter whose nitrogen is oxidized by the action of the atmosphere into nitric acid, which combines with the bases (potash and lime) contained in the soil. "The method employed in the artificial production of niter consists in placing animal matters, mingled with ashes and lime rubbish, in loosely aggregated heaps, exposed to the air, but sheltered from rain. The heaps are watered from time to time with urine or stable runnings; at suitable inter vals the earth is lixiviated, and the salt crystallized. Three years usually elapse before the niter bed is washed; after this interval a cubic foot of the debris should yield between 4 and 5 ounces of niter. As there is always a considerable quantity of time nitrates of lime and magnesia present, which will not crystallize, carbonate of potash. in the shape *of wood-ashes, is added so long as any precipitate occurs. The nitrate of lime is decomposed, and the insolubte carbonate of lime separated: Carbonate of Potash. Nitrate of Lime. Carbonate of Lime. Nitrate of Potash.