Influence of capillary condensation on the near-critical solvation force

We argue that in a fluid, or magnet, confined by adsorbing walls which favo r liquid, or the (+) phase, the solvation (Casimir) force in the vicinity o f the critical point is strongly influenced by capillary condensation which occurs below the bulk critical temperature T-c. At T slightly below and ab ove T-c, a small bulk field h < 0, which favors gas, or the (-) phase, lead s to residual condensation and a solvation force which is much more attract ive (at the same large wall separation) than that found exactly at the crit ical point. Our predictions are supported by results obtained from density- matrix renormalization-group calculations in a two-dimensional Ising strip subject to identical surface fields.