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EXPERIMENTS ON THE CATHODE DISCHARGE
DESCRIPTION of the BATTERY
The battery was based on the principle employed by
Poggendorff in his polarisation battery, and applied by Planté
to the cells which bear his name. The cells are arranged in
parallel, charged by a battery of comparatively small electro-
motive force, and then arranged in series. In this way very
high electromotive forces may be attained. It is not
necessary to deal singly with each cell thus: groups of five or
ten or more cells can be set up permanently in series; and
during the charging only these groups need be placed in
parallel. The larger the number of cells in each group, the
simpler does the commutating mechanism become; of course
the electromotive force required for charging increases at the
same time.
I arranged my cells in groups of five in series.
The cells were made of test-tubes, 125 mm. high, 14-15 mm.
in diameter, and were filled two-thirds deep with sulphuric
acid diluted with nine times its volume of water. The
electrodes were strips of lead of suitable length, 10 mm. broad
and 1 mm. thick, varnished at the top with asphalt varnish.
The neighbouring pairs of electrodes within each group of five
cells were formed by bending a single strip of lead (so that no
connecting wire was necessary); copper wires soldered to the
outer electrodes led to two glass mercury cups which formed
the poles of the group. The cells were cemented in fifties on
boards, of which five (or 250 cells) went in a box 84 cm. long,
12 cm. wide, and 17 cm. high. The 100 glass cups forming
the corresponding poles lay in a row on the front side of the
box. The commutation was effected by two interchangeable
commutators, of which one was used in charging and the other
in discharging. These were made of bent wires attached to
a strip of wood; the construction was simple and does not
require special explanation.
So long as the battery remained in good condition, it
worked as follows. Ten Bunsen or Grove cells were required
to charge it. When these had been in action for an hour the
battery was charged sufficiently for a day's work. The
difference of potential between its poles was about equal to
that of 1800 Daniell cells. Its internal resistance, as
M. P.
Q