Abstract: An apparatus for the development of an emulsion coating, especially of a film sheet of a film punched card, with a development chamber which is limited on one side by the emulsion coating and is arranged in the path of flow of fluid(s) for the one part and air for the other, is to be so improved that a minimum possible chemical consumption with optimum development operation ensue. More especially a development chamber of new conception is to be produced. For this purpose the development chamber (22) comprises a gap chamber (37) of rectangular plan of a height (i) of about 0.1 to 1.0 mm. and is limited in relation to a carrier surface, determining the position of the emulsion coating (12), of a frame rib (39) with seal edge (40) by the surface (35) of a heated chamber body (29).