1. battery, column The original Volta's pile. It consists of a series of compoundcircular plates, the upper or lower half, A, copper; the other, Z, of zinc. Between each pair of plates some flannel or cloth, u, u, is laid, which is saturated with dilute acid. As shown in the cut, the parts are laid up in two piles, connected at the top with a bar, c, c, and with vessels of acidulated water, b, b, as electrodes. The greatpoint in setting it up is to be sure that no acid runs from one disc of flannel to the next over the outside of the plates, as this would create a short circuit. The plates are best compound, being made up of a zinc and a copper plate soldered together. They may, however, be separate, and merely laid one on the other. In such case great care must be taken to admit no acid between them.
Volta's pile is no longer used, except occasionally. Trouvé's blotting paper battery (see Battery, Trouvé's) is a relic of it, and the same is to be said for Zamboni's dry pile.
It rapidly polarizes, the flannel retains but little acid, so that it is soon spent, and it is very troublesome to set up. Great care must be taken to have the cloth discs thoroughly saturated, and wrung out to avoid short circuiting by squeezing out of the acid.
Definitions of battery, column
