evaporated, and then shake it up well at the ordinary temperature with
hydrated oxide of zinc (zincic hydrate). Under this treatment the
greater portion of the zinc that had been chemically dissolved by the
potash is precipitated in the form of zinc hydrate, along with
some carbonate. The liquid is now allowed to settle, and the clear
supernatant solution is poured back again into the battery cells. The
battery has rather greater electromotive force when this regenerated lye
is used, because certain foreign matters from the carbon, like sulphur,
chlorine, sulphuric acid, etc., are removed by this treatment.

The regeneration of the (brown coal) carbon goes on of itself, beneath
the lye, through the oxidizing action of the atmospheric air; it is
advantageous to have a part of the carbon sticking out of the liquid. Of
course the regeneration takes place much more quickly if the electrodes
are taken out and exposed to the air. In this case the carbon electrode
need not be very thick, and can be flat or of tubular form. In the
former case it must have a large volume, and the massive cylindrical
form is recommended. The zinc electrode must be kept covered deeply with
potash. The cells must have free access of air, and the potash must be
replaced as soon as it is exhausted.--_Chem. Zeit_.

* * * * *

[Concluded from SUPPLEMENT No. 390, page 6217.]




THE CAUSE OF EVIDENT MAGNETISM IN IRON, STEEL, AND OTHER MAGNETIC
METALS.