The Collaborative International Dictionary of English v.0.48:

phosgene \phos"gene\ (f[o^]s"j[=e]n or f[o^]z"j[=e]n), n.
   (Chem.)
   A reactive chemical substance (COCl2), also called
   carbonyl choride, used in synthesis of numerous substances.
   In the First World War it was also used as a poisonous gas in
   combat.
   [PJC]

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]

The Collaborative International Dictionary of English v.0.48:

Cobaltous \Co*balt"ous\, a. (Chem.)
   Pertaining to, derived from, or containing, cobalt; -- said
   esp. of cobalt compounds in which the metal has its lower
   valence.
   [1913 Webster]

   Cobaltous chloride, a crystalline compound, CoCl2, of a
      pale rose color when hydrous, blue when dehydrated. Its
      solution is used for a sympathetic ink, the writing being
      nearly colorless when dried in the air, owing to absorbed
      moisture, and becoming bright blue when warmed.
      [1913 Webster]