The Collaborative International Dictionary of English v.0.48:

Fumatorium \Fu`ma*to"ri*um\, n.; L. pl. -ria. [NL., fr. L.
   fumare, fumatum, to smoke.]
   An air-tight compartment in which vapor may be generated to
   destroy germs or insects; esp., the apparatus used to destroy
   San Jos['e] scale on nursery stock, with hydrocyanic acid
   vapor.
   [Webster 1913 Suppl.]