SEPARATION OF IRON FROM MANGANESE.
If a solution of ferric oxide and manganese ammonium oxalate is
submitted to electrolysis, without the previous addition of ammonium
oxalate, the characteristic color of permanganic acid immediately makes
its appearance, and the peroxide gradually precipitates itself on the
positive, while the iron is deposited on the negative electrode. When
the examination is made in the above manner, it is impossible to
separate the two metals, for the peroxide will bring down with it a
considerable quantity of ferric hydrate. The separation of the two
metals is only possible when the precipitation of the manganese peroxide
is prevented, until the greater portion of the iron has been deposited.
This result may be attained by adding sodium phosphate, or, better
still, by the addition of ammonium oxalate in great excess. In both
cases the characteristic coloration from permanganic acid is developed
by the action of the current at the positive pole; this, however,
disappears in the direction of the negative electrode. After the greater
portion of the ammonium oxalate has been converted into carbonate, the
coloration and necessarily the formation of manganese peroxide begins.
Ammonium oxalate is added to the solution, and heat applied; then three
or four grammes more of ammonium oxalate are dissolved in the liquid,
which is then immediately submitted to electrolysis.
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