Cubic niter

Saltpeter \Salt`pe"ter\, Saltpetre \Salt`pe"tre\,
   (s[add]lt`p[=e]"t[~e]r), n. [F. salp[^e]tre, NL. sal petrae,
   literally, rock salt, or stone salt; so called because it
   exudes from rocks or walls. See {Salt}, and {Petrify}.]
   (Chem.)
   Potassium nitrate; niter; a white crystalline substance,
   {KNO3}, having a cooling saline taste, obtained by leaching
   from certain soils in which it is produced by the process of
   nitrification (see {Nitrification}, 2). It is a strong
   oxidizer, is the chief constituent of gunpowder, and is also
   used as an antiseptic in curing meat, and in medicine as a
   diuretic, diaphoretic, and refrigerant.
   [1913 Webster]

   {Chili salpeter} (Chem.), sodium nitrate (distinguished from
      potassium nitrate, or true salpeter), a white crystalline
      substance, {NaNO3}, having a cooling, saline, slightly
      bitter taste. It is obtained by leaching the soil of the
      rainless districts of Chili and Peru. It is deliquescent
      and cannot be used in gunpowder, but is employed in the
      production of nitric acid. Called also {cubic niter}.

   {Saltpeter acid} (Chem.), nitric acid; -- sometimes so called
      because made from saltpeter.
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Niter \Ni"ter\, Nitre \Ni"tre\, n. [F. nitre, L. nitrum native
   soda, natron, Gr. ?; cf. Ar. nit[=u]n, natr[=u]n natron. Cf.
   {Natron}.]
   1. (Chem.) A white crystalline semitransparent salt;
      potassium nitrate; saltpeter. See {Saltpeter}.
      [1913 Webster]

   2. (Chem.) Native sodium carbonate; natron. [Obs.]
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            For though thou wash thee with niter, and take thee
            much soap, yet thine iniquity is marked before me.
                                                  --Jer. ii. 22.
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   {Cubic niter}, a deliquescent salt, sodium nitrate, found as
      a native incrustation, like niter, in Peru and Chile,
      whence it is known also as {Chile saltpeter}.

   {Niter bush} (Bot.), a genus ({Nitraria}) of thorny shrubs
      bearing edible berries, and growing in the saline plains
      of Asia and Northern Africa.
      [1913 Webster]