phosgene gas

from The Collaborative International Dictionary of English v.0.48
Carbonyl \Car"bon*yl\, n. [Carbon + -yl.] (Chem.)
   The radical ({=CO}), occuring, always combined, in many
   compounds, as the aldehydes, the ketones, urea, carbonyl
   chloride, etc.
   [1913 Webster]

   Note: Though denoted by a formula identical with that of
         carbon monoxide, it is chemically distinct, as carbon
         seems to be divalent in carbon monoxide, but
         tetravalent in carbonyl compounds.
         [1913 Webster]

   {Carbonyl chloride} (Chem.), a colorless gas, {COCl2}, of
      offensive odor, and easily condensable to liquid. It is
      formed from chlorine and carbon monoxide, under the
      influence of light, and hence has been called {phosgene},
      or {phosgene gas}; -- called also {carbon oxychloride}. It
      is used in chemical synthesis, and was also used as a
      poison gas in World War I.
      [1913 Webster +PJC]
    

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