Source : Webster's Revised Unabridged Dictionary (1913)

Nitrum \Ni"trum\, n. [L., natron. See {Niter}.] (Old Chem.)
   Niter.

   {Nitrum flammans} [L., flaming niter] (Old Chem.), ammonium
      nitrate; -- probably so called because it deflagerates
      when suddenly heated.