Niter

Niter, or nitre ("chiefly British variant"^[4]), is the mineral form of potassium nitrate, KNO₃, also known as saltpeter or saltpetre. Historically, the term "niter" was not well differentiated from natron, both of which have been very vaguely defined but generally refer to compounds of sodium or potassium joined with carbonate or nitrate ions. Three related minerals are soda niter (sodium nitrate), ammonia niter (ammonium nitrate), and strontium nitrate. Niter was used to refer specifically to nitrated salts known as various types of saltpeter (only nitrated salts were good for making gunpowder) by the time niter and its derivative nitric acid were first used to name the element nitrogen, in 1790.

Because of its ready solubility in water, niter is most often found in arid environments. A major source of sodium nitrate mineral ("Chile saltpeter", that is, nitratine) is the Atacama desert in Chile. Potassium and other nitrates are of great importance for use in fertilizers and, historically, gunpowder. Much of the world's demand is now met by synthetically produced nitrates, though the natural mineral is still mined and is still of significant commercial value.

Description

Niter is a colorless to white mineral crystallizing in the orthorhombic crystal system. It usually is found as massive encrustations and efflorescent growths on cavern walls and ceilings where solutions containing alkali potassium and nitrate seep into the openings. It occasionally occurs as prismatic acicular crystal groups, and individual crystals commonly show twinning.

History

Niter as a term has been known since ancient times, although there is much historical confusion with natron (an impure sodium carbonate/bicarbonate), and not all of the ancient salts known by this name or similar names in the ancient world contained nitrate. The name is from the Greek νιτρων nitron from Ancient Egyptian netjeri, related to the Hebrew néter, for salt-derived ashes (their interrelationship is not clear).

The Hebrew néter may have been used as, or in conjunction with soap, as implied by Jeremiah 2:22, "For though thou wash thee with nitre, and take thee much soap ..." However, it is not certain which substance (or substances) the Biblical "neter" refers to, with some suggesting sodium carbonate. Indeed, the Neo Latin word for sodium, natrium, is derived from this same class of desert minerals called natron (French) from Spanish natrón through Greek νίτρον (nitron), derived from Ancient Egyptian netjeri, referring to the sodium carbonate salts occurring in the deserts of Egypt, not the nitrated sodium salts typically occurring in the deserts of Chile (classically known as "Chilean saltpeter" and variants of this term).^[5]

A term (ἀφρόνιτρον, aphronitron or Aphronitre) which translates as "foam of niter" was a regular purchase in a fourth-century AD series of financial accounts, and since it was expressed as being "for the baths" was probably used as soap.^[6]

Niter was used to refer specifically to nitrated salts known as various types of saltpeter (only nitrated salts were good for making gunpowder) by the time niter and its derivative nitric acid were first used to name the element nitrogen, in 1790.

See also

• Nitrary, a place for making saltpeter

References

External links

• Etymology of "niter"
• Niter page on mindat.org
• Niter page on webmineral.com
• Mineral galleries
• Poe's The Cask of Amontillado