A Process for Preserving the Surface of Copper or its Alloys.
Year: 1886

page_text: Date of Application, 24th Dec., 1886.
Complete Left, 15th Mar., 1887.
Complete Accepted, 15th Apr., 1887.
A Process for Preserving the Surface of Copper or its Alloys.
1, ERNEST DE PASS, of 68 Fleet Street, in the City of London, Fellow of the
Institute of Patent Agents, do hereby declare the nature of this invention to be as
follows:-
This process has for its object to produce on, or to apply to, the surface of copper,
special
and the alloys of copper, directly or indirectly adherent, a coating or film of a
salt of copper, undecomposable by strong acids; directly adherent when this salt is
developed in the nascent state on the copper itself; indirectly, when applied by means
of a mixture, varnish, or coating, formed with a base of the salt aforesaid.
For this purpose, the sulpho-cyanate of copper, or its analogue, the cyanate of
copper, is employed.
This patina constitutes the most effective and certain protection as it resists concen-
trated nitro-muriatic acid.
The means for developing or producing the patina may vary, as for instance:
1. The sulpho cyanic acid, or cyanic acid, may be caused to act on the copper by
dipping this latter into these acids, diluted with 50 parts of water.
2. Or by dipping into a solution composed of
Ammoniacal oxide of copper
1 part
Sulpho cyanate, or any soluble cyanate, (such as potassic,
ammonic or sodic salts)
2 parts
10 parts
Water
3. The surface to be coated is made the positive electrode in one of the above
mentioned salts.
4. The mixture by the wet or by the dry processes may likewise give rise to the
sulpho cyanate, or to the cyanate of copper; for this latter salt, for example, the
ordinary dry process for the production of cyanates naturally presents itself. Also, I
14

page_text: would select, as an instance, for the wet process, the reaction of sulphide of carbon
(1 part) on ammonia (3 parts) which furnishes the sulpho-cyanate of ammonia.
5. By using a saturated solution of sulpho cyanide of copper in aqueous ammonia,
and simply dipping, for about 1 hour, the objects to be treated.
These examples are only stated in order to give an idea of the different methods
which confirm the principle of the discovery, a principle entirely unknown, and
constituting, a priori, in obtaining sulpho cyanate or cyanate of copper on pure or
alloyed copper to protect it against oxidation and to electrically insulate it.
The sulpho-cyanate, or cyanate of copper, precipitated, dried, ground and mixed in
a solution of caoutchouc, or with a drying oil, resin, varnish, or any size, will add to
these already protecting bodies, quite special adherence and marked advantages.
Dated this 24th day of December 1886.

page_text: A Process for Preserving the Surface of Copper or its Alloys.
I, ERNEST DE PASS, of 68 Fleet Street, in the City of London, Fellow of the
Institute of Patent Agents; do hereby declare the nature of this invention, and in
what manner the same is to be performed, to be particularly described and ascertained
in and by the following statement, that is to say:
This process has for its object to produce on, or to apply to, the surface of copper,
and the alloys of copper, directly or indirectly adherent, a coating or film of a special
salt of copper, undecomposable by strong acids: directly adherent, when this salt is
developed in the nascent state on the copper itself: indirectly, when applied by means
of a mixture, varnish, or coating, formed with a base of the salt aforesaid.
For this purpose the sulpho-cyanate of copper, or its analogue, the cyanate of copper,
is employed.
This patina constitutes the most effective and certain protection, as it resists concen-
trated nitro-muriatic acid.
The means for developing or producing the patina may vary, as for instance :-
1. The sulpho cyanic acid, or cyanic acid, may be caused to act on the copper by
dipping this latter into these acids diluted with 50 parts of water.
2. Or by dipping into a solution composed of
Ammoniacal oxide of copper
-
1 part
2 parts
10 parts
Sulpho cyanate, or any soluble cyanate (such as potassic,
ammonic or sodic salts)
Water
-
3. The surface to be coated is made the positive electrode in one of the above
mentioned salts.
4. The mixture, by the wet or by the dry processes, may likewise give rise to the
sulpho-cyanate, or to the cyanate of copper; for this latter salt, for example, the
ordinary dry process for the production of cyanates naturally presents itself. Also, I
would select, as for instance, for the wet process, the reaction of sulphide of
carbon (1 part) on ammonia (3 parts) which furnishes the sulpho cyanate of ammonia.
5. By using a saturated solution of sulpho cyanide of copper in aqueous ammonia,
and simply dipping, for about 1 hour, the objects to be treated.
These examples are only stated in order to give an idea of the different methods
which confirm the principle of the discovery, a principle entirely unknown and
consisting, a priori, in obtaining sulpho cyanate or cyanate of copper on pure or
alloyed copper to protect it against oxidation, and to electrically insulate it.
The sulpho-cyanate, or cyanate of copper, precipitated, dried, ground, and mixed in
a solution of caoutchouc, or with a drying oil, resin, varnish, or any size, will add to
these already protecting bodies, quite special adherence and marked advantages.
It obvious that this invention may be carried into practice in various manners, and
that any mixture or reaction capable of forming or applying directly or indirectly
sulpho cyanate, or cyanate of copper, upon copper and its alloys will not be a departure

page_text: from the nature of the invention, while what is desired to claim is, the benefit of the
exclusive use of cyanic copper, or cyanated copper.
Thus the principle of the invention consists in forming upon copper, and its alloys,
and particularly upon brass (cartridge cases, wire frames for paper makers, electric
and telephone wires and the like) an intimate coating of cuprous sulpho cyanate or
rhodanide (CSN) Cu2. It is this patina, or coating, upon which mineral acids, with
the exception of nitric acid, have no action, that it is desired to protect by patent,
seeing that heretofore it has never been applied to manufacturing purposes in order to
protect copper, and its alloys, from various oxidizing actions.
I will cite only one instance in which this patina, or coating, can be obtained,
without the use of a solution of cuprous rhodanide, in ammonia.
The following bath is composed of:
1. Water
2. Rhodanide of ammonium
3. Liquid ammonia-
4. Sulphate of copper
100 parts
10 parts
10 parts
3 parts, previously dissolved.
The cupric solution is last added, as above stated. By immersing, for one hour, in
this bath, the copper or brass articles required to be protected, and by rinsing them in
a large quantity of water, there is formed on their surface an intimate layer or coating
which preserves them from being afterwards attacked.
It is obvious that this layer may likewise be obtained by modifying the above
quantities, and the bases of the rhodanides, but this however does not disprove that
the invention consists in the layer or coating itself. Equally well may be included in
the principle of this invention, the application of the analogue of cuprous rhodanide
(CSN) Cu², that is to say, the cuprous cyanate (CON) Cu³, which, while only
differing from the above by the substitution of oxygen for sulphur, offers with its
congeneries the greatest analogy as regards reactions and properties, as well as the
rhodanides and the cyanates which are alike.
Having now described the nature of the said invention, and in what manner the
same is to be performed, I declare that I claim, as communicated to me by my foreign
correspondents:
1. The herein described process for preserving the surface of pure or alloyed copper,
consisting in producing upon its surface an intimate layer of sulpho cyanate or of
cyanate of copper, or of cuprous sulpho cyanate or rhodanide, either by any one of the
above described reactions, or by any other, substantially as set forth.
2. The modification of the said process for preserving pure or alloyed copper,
consisting in covering its surface with an adherent layer of a mixture, varnish, or
coating, having a base of sulpho cyanate, or cyanate of copper, or of cuprous sulpho
cyanate or rhodanide, substantially as herein set forth.
Dated this 15th day of March 1887.