It is already known that manganese may be separated as the peroxide from
its nitric acid solution. We find, however, that the precipitation is
only completely effected when the quantity present is small; the amount
of nitric acid must also be slight, and it is necessary to wash the dish
without interrupting the current. If the manganese is converted into
the soluble double salt, prepared by adding an excess of potassium, and
submitted to the electric current, the whole of the manganese will be
deposited at the positive electrode. When ammonium oxalate is used, the
complete precipitation does not take place. As the separated peroxide
does not adhere firmly to the electrode, it is necessary to filter it
and convert it, by ignition, into the trimangano-tetroxide (Mn_3O_4).