334 °C
[1]400 °C decomp.[1]
Its common names include saltpetre, from Medieval Latin sal petrae "stone salt" or possibly "Salt of Petra" (saltpeter in US English), nitrate of potash, and nitre (US niter). For specific information about the naturally occurring mineral, see nitre. The name Chile saltpeter is applied to sodium nitrate, a different nitrogen compound that is also used in explosives and fertilizers.
Potassium nitrate is the oxidizing component of black powder. Before the large-scale industrial fixation of nitrogen through the Haber process, major sources of potassium nitrate were the deposits crystallizing from cave walls and the draining of decomposing organic material. Dung-heaps were a particularly common source ammonia from the decomposition of urea and other nitrogenous materials would undergo bacterial oxidation to produce nitrate. It was and is also used as a component in some fertilizers. When used by itself as a fertilizer, it has an NPK rating of 13-0-38 (indicating 13.9%, 0%, and 38.7% of nitrogen, phosphorus, and potassium, by mass, respectively). Potassium nitrate was once thought to induce impotence, and is still falsely rumored to be in institutional food (such as military fare) as an anaphrodisiac; these uses would be ineffective, since potassium nitrate has no such properties.[2] However, potassium nitrate and other nitrates do successfully combat high blood pressure and are used medically to relieve angina.
