capillary constant

A measure of surface tension defined, for two immiscible fluids in contact, by 2Tg(D - d), where T is the surface tension for the interface, g is the acceleration due to gravity, and D and d are the densities of the fluids. Usually one of these is air. The capillary constant is equal to the rise of a liquid in a capillary tube multiplied by the diameter by the radius of the tube.