\Cy*an"o*gen\ (s?-?n"?-j?n), n. [Gr. ky`anos a dark
blue substance + -gen: cf. F. cyanog[`e]ne. So called because
it produced blue dyes.] (Chem.)
A colorless, inflammable, poisonous gas, {C2N2}, with a
peach-blossom odor, so called from its tendency to form blue
compounds; obtained by heating ammonium oxalate, mercuric
cyanide, etc. It is obtained in combination, forming an
alkaline cyanide when nitrogen or a nitrogenous compound is
strongly ignited with carbon and soda or potash. It conducts
itself like a member of the halogen group of elements, and
shows a tendency to form complex compounds. The name is also
applied to the univalent radical, {CN} (the half molecule of
cyanogen proper), which was one of the first compound
radicals recognized.
Note: Cyanogen is found in the commercial substances,
      potassium cyanide, or prussiate of potash, yellow
      prussiate of potash, Prussian blue, Turnbull's blue,
      prussic acid, etc.