saltpeter; potassium nitrate; niter
Chemical term for potassium nitrate (KNO₃), historically used in gunpowder, fertilizers, and food preservation. The cross-reference to 硝酸カリウム indicates it is the same substance.
See also: 硝酸カリウム
Saltpeter has been used since ancient times as an ingredient in gunpowder.
Saltpeter is also called potassium nitrate.
nitrocalcite
Chile saltpeter; soda nitre
Compound of 硝 (saltpeter) and 石 (stone), reflecting its mineral origin. The exact historical derivation is uncertain.