- Supersaturation, homogeneous nucleation, and subsequent bubble growth and motion in immiscible liquid layers induced by counterdiffusion of gases at different temperatures are studied analytically. The range of the critical embryo size to initiate transient nucleation is determined between spontaneous and infinitely-slow nucleation. In addition, the ranges of bubble departure size and terminal rising velocity are evaluated together with the degree of superheat required for heat transfer to be the controlling mechanism. Numerical results are obtained for two special cases: (i) a composite with negligible surface resistances to heat and mass transfer, and (ii) a composite with one side insulated. The mechanics of microexplosion of emulsions is explained. 1981.