Edison-Lalande Cell.
This is a practical form of the old Lalande-Chaperon cell, and gives a steady, large current, being of low internal resistance, but is of low electromotive force, being less than .70 volt on closed circuit of medium resistance. Being of low internal resistance, however, its output is large—three cells of the type S; internal resistance, 0.025 ohm. Capacity, 300 ampere hours, will about equal one cell type E 5 of the Chloride Storage Battery. The elements of this cell consist of positive plates of amalgamated zinc, suspended on each side of negative plates of the black oxide of copper in an electrolyte solution of caustic potash. In action the decomposition of water forms an oxide of zinc from the positive element, which with the potash in combination leaves a soluble salt of zinc and potash. The hydrogen of the water acts on the oxide plates to form metallic copper, thus really reducing, instead of increasing, the internal resistance of the cell. A layer of heavy paraffin oil is poured on top of the solution to prevent the action of air.