Critical state of bubbles in liquid-gas solutions

According to homogeneous nucleation theory, the spontaneous formation of a bubble occurs in a liquid when a thermodynamic fluctuation of sufficient magnitude occurs to form a bubble of at least the critical size. Here we report the results of an experimental study of bubbles near the critical state. We examine both the stability of this state and the predicted value of the critical radius. Photographs of two bubbles simultaneously present in a liquid, one slightly larger than the critical size and the other slightly smaller, are presented. Subsequent photographs show the larger one to grow and the smaller one to dissolve. Hence the critical state is unstable and the critical radius lies between the initial radii of the two bubbles. A second series of tests was conducted to examine more carefully the value of the critical radius.