Fig. 41. COLUMN BATTERY.
Battery, Column.
The original Volta's pile. It consists of a series of compound circular
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 great point 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.
Battery, D'Arsonval's.
A battery of the Bunsen type, differing therefrom in the solutions. As
excitant in which the zinc electrode is immersed, the following solution
is used:
Water, 20 volumes;
Sulphuric Acid (purified by shaking with a little olive or similar oil),
1 volume;
hydrochloric acid, 1 volume.
As polarizer in which the carbon is immersed the following is used:
Nitric acid, 1 volume;
hydrochloric acid, 1 volume;
water acidulated with 1/20th sulphuric acid, 2 volumes.
Battery, de la Rue.
A battery with zinc positive and silver negative electrode; the
depolarizer is silver chloride; the excitant common salt or ammonium
chloride. The cut shows one of its forms of construction.
The right hand portion of the cut, Fig. 42, shows the zinc perforated at
C for the connection from the next silver plate. The next to it is the
negative electrode of silver around which a mass of silver chloride is
cast in cylindrical form. A is a parchment paper cylinder with two holes
near its top, through which the silver wire of the negative electrode is
threaded, as shown in B. A solution of 23 parts ammonium chloride in
1,000 parts of water is the approved excitant. Its electro-motive force
is 1.03 volts.
The jars are closed with paraffin.
Fig. 42. DE LA RUE'S BATTERY.