WordNet sense 1 ((used of substances) capable of being volatilized):

evaporable, vaporizable, volatilisable, volatilizable, vapourisable, vapourific

WordNet sense 2 (evaporating readily at normal temperatures and pressures):

volatile

WordNet sense 3 (resembling or characteristic of vapor):

vaporous, vaporish, vapourish, vapourous

WordNet sense 4 (existing as or having characteristics of a gas):

gaseous