ich forms water by combination with the already
liberated hydrogen and leaves what is termed a _sesquioxide_ of
manganese. This absorption or combination of the hydrogen prevents
immediate polarization, but hydrogen is evolved during the operation
of the cell more rapidly than it can combine with[typo was 'wth'] the
oxygen of the manganese, thereby leading to polarization more rapidly
than the depolarizer can prevent it when the cell is heavily worked.
When, however, the cell is left with its external circuit open for a
time, depolarization ensues by the gradual combination of the hydrogen
with the oxygen of the peroxide of manganese, and as a result the cell
recuperates and in a short time attains its normal electromotive
force.

The electromotive force of this cell when new is about 1.47 volts. The
internal resistance of the cell of the type shown in Fig. 61 is
approximately 1 ohm, ordinarily less rather than more.

A more recent form of LeClanche cell is shown in cross-section in Fig.
62. This uses practically the same materials and has the same chemical
action as the old disk LeClanche cell shown in Fig. 61. It dispenses,
however, with the porous cup and instead employs a carbon electrode,
which in itself forms a cup for the depolarizing agent.

[Illustration: Fig. 62. Carbon Cylinder LeClanche Cell]

The carbon electrode is in the form of a corrugated hollow cylinder
which engages by means of an internal screw thread a corresponding
screw thread on the outer side of the carbon cover. Within this
cylinder is contained a mixture of broken carbon and peroxide of
manganese. The zinc electrode is in the form of a hollow cylinder
almost surrounding the carbon electrode and separated therefrom by
means of heavy rubber bands stretched around the carbon. The rod,
forming the terminal of the zinc, passes through a porcelain bushing
on the cover plate to obviate short circuits. This type of cell has an
electromotive force of about 1.55 volts and recuperates very quickly
after severe use. It also has considerably lower internal resistance
than the type of LeClanche cell employing a porous cup, and,
therefore, is capable of generating a considerably larger current.

Cells of this general type have assumed a variety of forms. In some
the carbon electrode, together with the broken carbon and peroxide of
manganese, were packed into a canvas bag which was suspended in the
electrolyte and usually surrounded by the zinc electrod