Improvements in the Electro-deposition of Metals.
Year: 1899

page_text: Date of Application, 13th Mar., 1899
Complete Specification Left, 12th Dec., 1899-Accepted, 13th Jan.,
1900
PROVISIONAL SPECIFICATION.
Improvements in the Electro-deposition of Metals.
I, AUGUST ZIMMERMANN, of 9 and 10, St. Mary at Hill, in the City of London,
Merchant, do hereby declare the nature of this invention (which has been
communicated to me from abroad by Dr. Courant, of 14 and 15 Johannisstrasse,
Berlin, in the Empire of Germany, Chemist), to be as follows:
The trouble in working with potassium cyanide in manufacturing baths
(copper, silver and the like) containing potassium cyanide has given rise to
repeated experiments for the entire superseding of potassium cyanide. Such
baths have however not been adopted. It has also been attempted to utilize
the double cyanide compounds such as potassium cuprocyanide and potassium
zinc cyanide. These compounds have however not come into use owing to their
extraordinary deliquescence and instability.
The following process has for its object not the exclusion of potassium cyanide
but the delivery to the manufacturer of a salt ready for use, and which forms
the complete electrolyte on dissolving in cold water, without further addition.
The copper electrolyte for example may be made as follows. Cuprous oxide,
in a pure state, is dissolved in potassium cyanide, thereby forming the
body Cu, Cy, 4 K Cy K, O. This compound is treated with sulphurous acid,
whereby by careful manipulation the triple salt Cu, Cy, 4 K Cy K, SO, is obtained.
This triple salt, which is most stable, forms when dissolved in water the
finished copper electrolyte of remarkable purity and great conductibility.
In like manner the zinc triple salt Zn Cy, 2K Cy K, SO,, the silver triple
salt Ag, Cy, 4 K Cy K, SO, the gold triple salt Au, Cy, 2K Cy K, SO, may be pro-
duced.
Dotad this 11th dow of Manch 1900
I, AUGUST ZIMMERMANN, of 9 and 10, St. Mary at Hill, in the City of London,
Merchant, do hereby declare the nature of this invention (which has been
communicated to me from abroad by Dr. Courant, of 14 and 15 Johannisstrasse,
Berlin, in the Empire of Germany, Chemist), and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement:―
The trouble in working with potassium cyanide in manufacturing baths
(copper, silver and the like) containing potassium cyanide has given rise to
repeated experiments for the entire superseding of potassium cyanide. Such

page_text: baths have however not been adopted. It has also been attempted to utilize
the double cyanide compounds such as potassium cuprocyanide and potassium
zinc cyanide. These compounds have however not come into use owing to their
extraordinary deliquescence and instability.
The following process has for its object the delivery to the manufacturer of
a salt ready for use, and which forms the complete electrolyte on dissolving in
cold water, without further addition.
The copper electrolyte for example may be made as follows. Cuprous oxide,
in a pure state, is dissolved in potassium cyanide, thereby forming the
body Cu, Cy, 4K Cy K, O. This compound is treated with so much sulphurous
acid, that the H, O contained therein is accurately saturated. By this means the
triple salt Cu, Cy, 4K Cy K, SO,, is obtained.
This triple salt, which is most stable, forms when dissolved in water the
finished copper electrolyte of remarkable purity and great conductibility.
In like manner the zine triple salt Zn Cy, 2K Cy K₂SO, the silver triple
salt Ag, Cy, 2K Cy K, SO, the gold triple salt Au, Cy, 2 K Cy K, SO3, the nickel
triple salt Ni Cy, 2K Cy K, SO, may be produced.
All these salts are soluble in water and at once form an electrolyte ready
for use and of great purity and conductibility.
By the use of these triple salts it is easy to control the amount of metal. in
the baths, further old baths are easily regenerated as it is only necessary to
dissolve a certain quantity of the triple salt in question.
By varying the mixtures of the copper triple salt and of the zinc triple salt
bronze and brass baths of different intensity and different shades of colour are
obtained.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I. declare that what
I claim is:
1. Electrolytes for potassium cyanide baths consisting of the potassium
cyanide double salt of the metal to be precipitated treated with sulphurous
acid.
2. The improved electrolytes substantially as described.