History

In the 9th century, Chinese chemists discovered that a mixture of potassium nitrate, sulfur, and charcoal would spontaneously produce smoke and flames. By the 11th century, the Chinese were incorporating the mixture, of gunpowder, into smoke bombs to help fight off enemies, and in the 13th and 14th centuries, they used this explosive power to propel objects at their foes with guns.

Historically in the United States, in the early to mid-19th century, caves in Kentucky, Tennessee, and West Virginia were extensively mined for saltpeter that was used to manufacture gunpowder. As more applications of potassium nitrate were discovered, the demand for the chemical compound increased. The increased demand shifted its production from the caves, where only a finite amount of the chemical could be manufactured, to industrial labs, with a much higher ability for production.