The Swelling of Thin, Gelatin Layers

The course of the swelling of gelatin, or emulsion layers of the usual thicknesses, can be closely matched by a curve generated according to the equation S/(Z -S) = ktn, where 5 is the swell at times t, Z is the equilibrium swell at saturation and k and n are constants. The equation allows the whole swell curve to be predicted from measurements taken in the early stages of swelling. A program for a Hewlett Packard System 35 computer extracts values for Z, k and n.