Potassium nitrate is an ionic salt composed of potassium ions and nitrate ions. It is naturally occurring in caves and sometimes known by the common name saltpeter, and is commonly produced from nitric acid commercially. Its molecular formula is KNO3 and has properties including a white, solid appearance, lack of distinguishable odor, and a crystalline structure. It has a melting point of 334 degrees Celsius and a boiling point of 400 degrees Celsius. It is soluble in glycerol and ammonia and partially dissolves in ethanol.
The ionic salt has a history of use as a fertilizer for its source of nitrogen and potassium. It is also used as an effective oxidizer, often in the context of black powder production, fireworks and cigarettes. In pharmacology, it is used in toothpaste to reduce sensitivity of the teeth, and is often used to treat asthma. Historically, it has been used in food preservation, primarily as a brine for salting meat, and it is still approved as a food additive in the United States.