The Collaborative International Dictionary of English v.0.48:

Expansile \Ex*pan"sile\, a.
   Expansible.
   [1913 Webster]

         Ether and alcohol are more expansile than water.
                                                  --Brande & C.
   [1913 Webster]

WordNet (r) 3.0 (2006):

expansile
    adj 1: (of gases) capable of expansion [syn: expandable,
           expandible, expansible, expansile]