The nitric solution of lead acts similarly to that of manganese. When
the amount of peroxide separated is so large that it does not adhere
firmly, and becomes mechanically precipitated on the negative electrode,
it becomes impossible to complete the estimation without loss from the
solution of the peroxide, and the results cannot be accepted.
If the double oxalate is submitted to electrolysis, the whole of the
lead is separated out in its metallic state, but it is so rapidly
oxidized by the air that it is very seldom that it can be dried without
decomposition even when the operation is conducted in a current of
illuminating gas. The electrolytic estimation of this element cannot be
recommended.