The estimation of interaction between bodies separated by a slit is a classical problem of surface science, whose solution lays a foundation for the theory of stability of colloidal systems. For dispersion forces without retardation, the pair potential of molecular interaction φ_ij(R) asymptotically is φ_ij(R) = -A_ijR^-6, where A_ij is the interaction constant and R is a distance between interacting molecules of sorts i and j. According to the symmetry of a finite slit, there are four nonzero components of the stress tensor, namely, E _xx, E_yy, E_zz, and E_xz, if x, y, and z are Cartesian coordinates with the z-axis directed normally and the other axes along the slit. Naturally, the existence of force f(x) induces internal stresses and strains in a solid at the slit edge.