Coulomb bubbles, though stable against monopole displacement, are unstable at least with respect to quadrupole and octupole distortions. We show that there exists a temperature at which the pressure of the vapor filling the bubble stabilizes all the radial modes. In extremely thin bubbles, the crispation modes become unstable due to the surface-surface interaction.

4 pages, TeX, epsfig, also available at http://csa5.lbl.gov/moretto/ps/bubble.ps, submitted to Phys. Rev. Lett