Fig. 1 represents a very simple arrangement. At the bottom of a glass
jar, V, we place a box of sheet iron, A, containing oxide of copper,
B. To this box is attached a copper wire insulated from the zinc by a
piece of India rubber tube. The zinc is formed of a thick wire of this
metal coiled in the form of a flat spiral, D, and suspended from a
cover, E, which carries a terminal, F, connected with the zinc; an
India-rubber tube, G, covers the zinc at the place where it dips into
the liquid, to prevent its being eaten away at this level.

The jar is filled with a solution containing 30 or 40 per cent. of
potash. This arrangement is similar to that of a Callaud element, with
this difference--that the depolarizing element is solid and insoluble.

[Illustration: FIG. 1.]

To prevent the inconveniences of the manipulation of the potash, we
inclose a quantity of this substance in the solid state necessary for
an element in the box which receives the oxide of copper, and furnish
it with a cover supported by a ring of caoutchouc. It suffices then
for working the battery to open the box of potash, to place it at the
bottom of the jar, and to add water to dissolve the potash; we then
pour in the copper oxide inclosed in a bag.

We also form the oxide of copper very conveniently into blocks. Among
the various means which might be employed, we prefer the following:

We mix with the oxide of copper oxychloride of magnesium in the form
of paste so as to convert the whole into a thick mass, which we
introduce into metal boxes.