This form of battery is very extensively used, and consists of a platinized silver plate for the negative element, with zinc plates for the positive, as in Fig. 39. The platinized silver plate is usually attached to a wooden bar, and the zinc plates, placed one on each side of it, are kept in position by a metallic cramp passing over the top of the bar. A binding screw, passed through the wooden bar and attached to the silver plate, forms the anode, and a similar binding screw, on the cramp that holds the zincs to the bar, is the cathode. An earthenware containing-vessel is required; the battery is excited by dilute sulphuric acid (7 volumes of water to one of acid). This battery is admirably adapted for electro-depositing and general galvanic experiments; but it is not suitable for producing electric light, nor for intensity coils. It is easily managed, tolerably constant, and requires only one exciting fluid: therefore, porous cells are dispensed with. (Dyer.)

Fig. 39.