The copper may be very easily and rapidly separated from the double
ammonium oxalate salt, provided a sufficient excess of ammonium oxalate
is present. Weak currents cannot be employed for the determination of
this element when it is present in large quantities, for under such
circumstances the metal does not adhere with sufficient firmness to the
electrode. We employed a current which corresponded to an evolution of
330 c.c. of gas per hour, and we were able to precipitate 0.15 gramme
metallic copper in about twenty-five minutes.