Potassium nitrate

Potassium nitrate is a chemical compound with a sharp, salty, bitter taste and the chemical formula KNO3. It is an ionic salt of potassium ions K+ and nitrate ions NO3−, and is therefore an alkali metal nitrate. It occurs in nature as a mineral, niter (or nitre in the UK). It is a source of nitrogen, and nitrogen was named after niter. Potassium nitrate is one of several nitrogen-containing compounds collectively referred to as saltpeter (or saltpetre in the UK). Major uses of potassium nitrate are in fertilizers, tree stump removal, rocket propellants and fireworks. It is one of the major constituents of gunpowder (black powder). In processed meats, potassium nitrate reacts with hemoglobin and myoglobin generating a red color. Potash, or potassium nitrate, because of its early and global use and production, has many names. The chemical potassium was first isolated by the chemist Sir Humphry Davy, from pot ash. This refers to an early method of extracting various potassium salts: by placing in an iron pot the ash of burnt wood or tree leaves, adding water, heating, and evaporating the solution. As for nitrate, Hebrew and Egyptian words for it had the consonants n-t-r, indicating likely cognation in the Greek nitron, which was Latinised to nitrum or nitrium. Thence Old French had niter and Middle English nitre. By the 15th century, Europeans referred to it as saltpetre, specifically Indian saltpetre (sodium nitrate is chile saltpetre) and later as nitrate of potash, as the chemistry of the compound was more fully understood. The Arabs called it "Chinese snow" (ثلج الصين ). It was called "Chinese salt" by the Iranians/Persians or "salt from Chinese salt marshes" (نمک شوره چينی ). Nitre#Availability In Ancient India, saltpeter manufacturers formed the Nuniya & Labana caste. Saltpeter finds mention in Kautilya's Arthashastra (compiled 300BC - 300AD), which mentions using its poisonous smoke as a weapon of war, although its use for propulsion did not appear until medieval times.