Renewing Dry Batteries with Sal Ammoniac
Finding that dry batteries had increased in price, and requiring a number for experimental purposes, I devised the following method by which I was able to use the old batteries for a considerable period: When the dry cells were nearly exhausted, I punched holes through the zinc covering with a nail, as shown in the sketch. The holes were placed about 1¹⁄₂ in. apart, and care was taken not to punch them near the upper edge of the container, or the black insulation might thus be injured. The cells were then placed in a saturated solution of sal ammoniac. The vessel containing the liquid must be filled only to within ¹⁄₂ in. from the top of the cell, otherwise the binding posts will be corroded, and the cell probably short-circuited. The cells were left in the solution six hours, and then became remarkably live. They must not be connected or permitted to come into contact with each other while in the solution.—H. Sterling Parker, Brooklyn, N. Y.