Saltpeter

a compound of nitric acid and potassium, known as potassium or potassic nitrate. It is obtained for sale in considerable quantities in the caverns of Kentucky and Tennessee, where it occurs as an incrustation. Saltpeter is found also in India, Persia, Egypt, and Spain. Of late it is obtained in commercial quantities from so-called saltpeter deposits in Chile, Peru, Bolivia, Nevada, and California. The saltpeter deposits of Chile yield $27,000,-000 worth annually. Saltpeter is used in dyeing clothing, in melting metals, in medicines, in curing meats, and especially in the manufacture of gunpowder. See Gunpowder