Abstract: This invention is directed to a film unit composed of a support carrying on one side a processing composition permeable layer containing an acid reacting reagent therein, and, on the other side, silver precipitating nuclei and photosensitive silver halide crystals. The above film unit is particularly suitable for use as motion picture film, i.e., in the form of an elongated web wherein said film unit is unwound, exposed, contacted with a photographic processing composition containing, e.g., a silver halide developing agent and silver halide solvent, rolling said film unit upon itself thereby contacting the processing composition permeable layer with the layers on the opposite side of the support. The acid reacting agent will diffuse into the silver halide and nuclei containing layers providing enhanced stability to the film unit.