The three models of a secondary battery that I recently made known to the
readers of this journal have been the object of continuous experiment.
Conformably to the provisions of theory, the zinc accumulator has shown
itself practically superior to the two others, and I have therefore chosen
this type for getting up an industrial model, which is shown in the
annexed cut. The accumulator contains four Planté positives, having a wide
surface, and three negatives constructed of smooth sheets of lead covered
with zinc by the electrolysis of the acidulated solution of zinc sulphate
in which the couple is immersed. Accidental contact with the interior of
the pile is prevented by glass tubes fixed to the negatives by means of
leaden bands. The seven electrodes are carried by as many distinct
crosspieces of paraffined wood, which rest upon the edges of the trough
and hold the plates at a certain distance from the bottom. These various
crosspieces, which touch one another, take the place of a cover. Each
plate is provided with a terminal. The four positive terminals are all on
the same side, and the three negatives are on the opposite side. Two brass
rods ending in a wire-clamp connect the respective terminals of the same
name. The trough consists of two oblong wooden receptacles, one within the
other, and having a play of several millimeters. This space is lined with
a tight, elastic, insulating cement having tar for a base.
[Illustration: REYNIER'S ZINC ACCUMULATOR. (One-fifth actual size.)]
The careful insulation of the trough and all parts of the apparatus, and
the purity of the metal and its amalgamation, reduce the local attack of
the zinc to almost nothing. So the coefficient of restitution is now
comparable with that of accumulators of the Planté type.
The following are the principal numerical data of the new zinc
accumulator.