Fig. 46 shows a form with porous cup. The binding-post at the top of the carbon plate forms the + electrode, the current leaving the cell at this point.
Fig. 49.
The Gonda Prism Cell (Fig. 47), is a form of Leclanché in which the depolarizer is in the form of a cake.
Fig. 50.
58. Dry Cells are open circuit cells, and can be carried about, although they are moist inside. The + pole is the end of the carbon plate. Zinc is used as the outside case and + plate. Fig. 48 shows the ordinary forms.
Fig. 49 shows a number of dry cells arranged in a box with switch in front, so that the current can be regulated at will.
59. The Edison-Lelande Cells, Fig. 50, are made in several sizes and types. Zinc and copper oxide, which is pressed into plates, form the elements. The exciting fluid consists of a 25 per cent. solution of caustic potash in water. They are designed for both open and closed circuit work.