Niter

Niter (American English) or nitre (most English-speaking countries) is the mineral form of potassium nitrate, KNO₃, also known as saltpeter in America or saltpetre in other English speaking countries. Historically, the term "niter" – cognate with "natrium", a Latin word for sodium – has been very vaguely defined, and it has been applied to a variety of other minerals and chemical compounds, including sodium nitrate (also "soda niter", "cubic niter", or nitratine), sodium carbonate and potassium carbonate.