rage battery. His original
cell consisted of two plates of metallic lead immersed in dilute
sulphuric acid. The acid formed a thin layer of lead sulphate on each
plate which soon stopped further action on the lead. If a current was
passed through the cell, the lead sulphate on the "anode" or lead
plate at which the current entered the cell was changed into peroxide
of lead, while the sulphate on the other lead plate or "cathode" was
changed into pure lead in a spongy form. This cell was allowed to
stand for several days and was then "discharged," lead sulphate being
again formed on each plate. Each time this cell was charged, more
"spongy" lead and peroxide of lead were formed. These are called the
"active" materials, because it is by the chemical action between them
and the sulphuric acid that the electricity is produced. Evidently,
the more active materials the plates contained, the longer the
chemical action between the acid and active materials could take
place, and hence the greater the "capacity," or amount of electricity
furnished by the cell. The process of charging and discharging the
battery so as to increase the amount of active material, is called
"forming" the plates.

[Fig. 19 Illustration of chemical action in a storage cell
during charge]

Plante's method of forming plates was very slow, tedious, and
expensive. If the spongy lead, and peroxide of lead could be made
quickly from materials which could be spread over the plates, much
time and expense could be saved. It was Faure who first suggested such
a plan, and gave us the "pasted" plate of today, which consists of a
skeleton framework of lead, with the sponge lead and peroxide of lead
filling the spaces between the "ribs" of the framework. Such plates
are known as "pasted" plates, and are much lighter and more
satisfactory, for automobile work than the heavy solid lead plates of
Plante's. Chapter 3 describes more fully the processes of
manufacturing and pasting the plates.

We know now what constitutes a storage battery, and what the parts are
that "generate" the electricity. How is the electricity produced?
Theoretically, if we take a battery which has been entirely
discharged, so that it is no longer able to cause a flow of current,
and examine and test the electrolyte and the materials on the plates,
we shall find that the electrolyte is pure water, and both sets of
plates composed of white lead sulphate. On the other hand, if we make
a si