A closed, nonrepellent metal tank was filled with a wall-wetting liquid and its vapor. The principle of minimum surface energy was used to investigate the stable configuration of the liquid in a zero-g field. A solution of the isoperimetrical problem for double integrals was obtained which includes the classical spherical solution as a special case. It was found that if the liquid wets the tank wall, it will cling to it and leave a vapor bubble in the tank. The surface of the bubble is a surface of revolution. The exact shape depends upon the ratio of the volume of the liquid to that of the vapor. The result thus obtained was applied to a tank with a surface of revolution. Conditions are given for the case where the bubble will be a sphere. It was found that the temperature rise on the tank wall will create bubbles tangential to the wall. These bubbles will pulsate until they become large enough to touch each other, then they will coalesce to form a larger bubble which will eventually join the central bubble by contact. Small rotational disturbances were found to have a stabilizing effect. In case of a nonwetting liquid like mercury, it was found that the liquid will detach it self from the wall and form a sphere in the center of the tank.