By H.B. SLATER.
To those interested in the electro deposition of nickel upon zinc, the
formula given below for a solution and a brief explanation of its use
will be of service.
The first sample of this solution was made as an experiment to see what
substances could be added to a solution of the double sulphate of nickel
and ammonium without spoiling it.
In addition to several other combinations and mixtures of solutions from
which I succeeded in obtaining a good deposit, I found that the solution
here given would plate almost anything I put into it, and worked
especially well upon zinc. In its use no "scraping" or rescouring or any
of the many operations which I have seen recommended for zinc needs
be resorted to, as the metal "strikes" at once and is deposited in
a continuous adherent film of reguline metal, and can be laid on as
heavily as nickel is deposited generally.
I believe that the addition of the ammonium chloride simply reduces
the resistance of the double sulphate solution, but the office of the
potassium chloride is not so easily explained. At least, I have never
been able to explain it satisfactorily to myself. It is certain,
however, that the solution does not work as well without it, nor does
the addition of ammonium chloride in its stead give as fine a result.
Some care is necessary in the management of the current, which should
have a density of about 17 amperes per square foot of surface--not much
above or below. This may seem a high figure, especially when it is
discovered that there is a considerable evolution of gas during the
operation.
I have repeatedly used this solution for coating articles of zinc, and
always with good success. I have exhibited samples of zinc plated in
this solution to those conversant with the deposition of nickel, and
they have expressed surprise at the appearance of the work. Some strips
of sheet-zinc in my possession have been bent and cut into every
conceivable shape without a sign of fracture or curling up at the edges
of the nickel coating.