STORAGE BATTERIES

sometime secondary batteries or accumulators are devices for the direct transformation of chemical energy into electrical energy, in which the chemical conditions after discharge are brought back to the original state by pa ing a current in the reverse direction. While the batteries are not completely reversible, that is, more energy must be supplied to them than can be taken from them, their high capacity and generally favorable characteristics have resulted in their wide adaptation to many uses. Among these may be cited,—to operate lights and self starters in automobiles, to drive electric trucks, to operate industrial locomotives where fire hazard is great, and in mines, etc., to operate submarines when submerged, to light railroad cars, to operate railroad signal system, to act as “stand-bys’’ in electric light plants, to operate radio apparatus, etc. etc. There are two common types, the lead sulphuric acid type which is most widely used and the nickel-iron-potash battery. The former type consists of lead plates immersed in a sulphuric acid solution. The positive plate is coated with lead peroxide (PbO:) and the negative plate with finely divided sponge lead. When the battery discharges, the active material on both plates is converted into lead sulphate (PbSO.) at the expense of the acid radical of the electrolyte. Subsequent charging liberates this SO, radical which by combination with nascent hydrogen also liberated, regenerates sulphuric acid and the plates are converted to their original condition. The Tron-Nickel-Potash type is best represented by the Edison Battery. The Hubbell Battery (used to some extent for miners lamps) differs from the Edison in the use of cadmium negative plates instead of iron ones. The Edison positive plate is of nickel, coated with nickel peroxide (NiO:) and the negative plate is of iron coated with finely divided iron. The electrolyte is a 21% solution of Pota ium hydroxide in water.