D.), and the zinc as well as the sal ammoniac are converted into
products that cannot be utilized.

I replace the solution of sal ammoniac by one of caustic potash or
soda (12 to 15 per cent.), and the thin zinc rods by zincs with larger
surfaces. In this manner, I obtain a powerful and odorless battery,
having all the valuable qualities of the Leclanche, and one that
permits of a renewal of the potash solution as well as of the negative
electrode.

The electromotive power of this element may be as high as 1.8 D. The
same pyrolusite (binoxide of manganese) cylinder used with the same thin
rod of zinc will precipitate 75 per cent. more copper from solution in
an hour when caustic potash is used than when sal ammoniac is employed.
But by replacing the thin zinc rod by a zinc cylinder of large surface,
21/2 times as much copper is precipitated in the same time.

The more powerful action of such a pair is explained by the stronger
excitation and more rapid regeneration that the negative electrodes
undergo from the oxidizing action of the air in the potash solution, as
well as by the fact that this solution is a better conductor than the
sal ammoniac solution. The potash solution does not crystallize easily,
hence the negative electrode remains free from crystals and does not
require filling up with water. Zinc dissolves only while in contact
with negative bodies, hence there is no unnecessary consumption of zinc
either in the open or closed circuit.

When the potash lye has become useless, I regenerate it by removing the
zinc in the following manner: I pour the solution from the cells, put
it in a suitable vessel, where I add water to replace that already