The Collaborative International Dictionary of English v.0.48:

Dephlogisticcate \De`phlo*gis"tic*cate\, v. t. [imp. & p. p.
   Dephlogisticated; p. pr. & vb. n. Dephlogisticating.]
   [Pref. de- + phlosticate: cf. F. d['e]phlogistiguer.] (O.
   Chem.)
   To deprive of phlogiston, or the supposed principle of
   inflammability. --Priestley.
   [1913 Webster]

   Dephlogisticated air, oxygen gas; -- so called by Dr.
      Priestly and others of his time. --
      De`phlo*gis`ti*ca"tion, n.
      [1913 Webster]