The Collaborative International Dictionary of English v.0.48:

Gasify \Gas"i*fy\, v. t. [imp. & p. p. Gasified; p. pr. & vb.
   n. Gasifying.] [Gas + -fy.]
   To convert into a gas, as by the application of heat, or by
   chemical processes.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Gasify \Gas"i*fy\, v. i.
   To become gas; to pass from a liquid to a gaseous state.
   --Scientific American.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gasify
    v 1: turn into gas; "The substance gasified" [syn: gasify,
         vaporize, vaporise, aerify]