9390. Poppenburg, J., von der. April 25. Secondary batteries.-Consists of improvements in the electrodes described in Specification No. 16,408, A,D. 1900. A conducting-grating a, provided with curved or bent projecting ends d is inserted in a frame, made in one piece preferably, or of as few pieces as possible, with non-conducting lateral portions e of material such as vulcanized rubber, so that the projections d come opposite grooves, holes, or recesses g, Fig. 4, in the frame. For this purpose, the frame is placed on a flat support h of glass or the like, and an aluminium or other suitable plate i fitted exactly in the frame so as just to reach to the recesses &c. as shown. The curved projections d are then flattened, separately or all together, thus locking the grid in its frame without the necessity of supports &c. as hitherto. The active material is then applied to both sides of the grid, and supported by transverse or longitudinal non-conducting bars connected to the frame in a suitable manner or by other, means. The upper part of the grid a, which lies in recesses in the frame, is covered by slides s to prevent access of the electrolyte to it. The electrodes may be bent or curved either after casting, or during the casting process. The grating may have free ends m, Fig. 7, which, after insertion into recesses n in the upper part of the frame, are soldered to a transverse part o, shown in dotted lines.