Nitre

Nitre, known also as saltpetre, consists chemically of nitrate of potassium (KN03), and was known to the early alchemists under the names of sal nitri and salpetras. The latter name is derived from the fact that in some countries it is obtained by the lixiviation of certain felspathic rocks. It occurs as an efflorescence on the soil in many tropical regions. It occurs thus owing to the decomposition of organic nitrogenous matter under the influence of certain bacteria [Nitrification], and this action is still largely adopted for its artificial preparation. It is now very largely produced by heating potassium chloride and Chili saltpetre (sodium nitrate) in strong solutions. The nitre remains in solution, and common salt is precipitated.