In order to prevent the reduced metal from oxidation, the
last traces of water are completely removed by repeated washings with
alcohol and anhydrous ether.
DETERMINATION OF LEAD.
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.
DETERMINATION OF COPPER.
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.
Pages:
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120