Abstract: A scanner for photographic processors wherein density and surface area determinations of the photosensitive materials can be exactly and reliably determined within a large density range. Optoelectronic sensor elements are arranged in the scanner which are formed of a transmitted light operated IR transmitter/receiver arrangement and of an IR reflective sensor arrangement located in rows and alternating across the width of the scanner.

Abstract: A cylindrical electrolysis tank (10) whose inner wall surface (11c) is held in contact with a single-use cathode (30) defining a hollow cylinder is provided with a removable tank lid (14) which forms an integral unit with a hollow cylinder (16) which carries the anode (34) on its peripheral surface (16a) and is provided with an uninterrupted closed bottom plate (17). The cylinder space (24) which is freely accessible from above serves to accommodate a replacement cathode (30) which is rolled up. At the circumferential abutment edge (18) between the peripheral surface (16a) of hollow cylinder (16) and the inner surface (19a) of lid plate (19) a ventilation groove (20) is provided which has a bore (20a) including an air-exhaust valve (21) and extending to the exterior.

Abstract: A device for the electrolytic recovery of silver comprises a cylindrical electrolysis tank (10) made of plastic, against the inner wall surface (11c) of which rests an expendable cathode (30) which is formed into a hollow cylinder and consists of a sheet-type plastic carrier (31) to which a carbon sheet (32) has been applied by bonding.In the rim areas of the tank bottom (12) and the lower side of the removable top (14), projections (13, 15) are provided which extend into the tank (10) and have inclined portions (13a, 15a) extending away from the inner wall surface (11c) and behind which the lower rim portion (31a) and the upper rim portion (31b) of the carrier sheet (31) of the expendable cathode (30) are held, said carrier sheet extending further than the carbon sheet (32).