A collection of batteries seen from above. The upper face of the centre battery has been cut away to reveal the contents. This type of battery, a dry version of the Leclanche cell, is called a carbon-zinc primary cell. A carbon rod sits upright in the centre and acts as a cathode (negative electrode). The outer vessel is made of zinc and thus serves a double purpose as container and anode (positive electrode). The electrodes are in contact with a moist electrolytic paste (the grey material visible here) consisting of ammonium & zinc chlorides, manganese dioxide and carbon particles.