Aluminium and Copper by Electro-deposition.
Year: 1887

page_text: Date of Application, 19th Feb., 1887.
Complete Left, 21st July, 1887.
Complete Accepted, 23rd Aug., 1887.
Aluminium and Copper by Electro-deposition.
We CHARLES ANTHONY BURGHARDT of King Street in the City of Manchester,
County of Lancaster, Analytical Chemist, and WILLIAM JAMES TWINING of St. Bees
Street, in the same City, Electro-Plater do hereby declare the nature of this Invention
to be as follows:-
Our Invention has for its object to obtain Aluminium and alloys of that metal with
copper by electro deposition from chemical solutions. We prepare a solution contain-
ing cyanides of the two metals aluminium and copper and obtain the alloy from such
solution by electro deposition or we throw down the copper and obtain the remaining
aluminium by electro deposition the alloy or metal being produced either as a
precipitate or as a deposit upon a surface or body as in ordinary electro plating or
deposition. In the preparation of the said solution we dissolve copper with nitro
hydrochloric acid and drive off the nitric acid by evaporating the solution to dryness
hydrochloric acid being added if necessary. The resultant is a slightly acid chloride
of copper. We prepare hydrated oxide of aluminium (al, 0, 3H, O) by adding
an excess of liquid ammonia to a solution of aluminium sulphate or of a suitable salt
of aluminium. We wash the precipitate to free it from foreign salts and mix it with
the aforesaid acid chloride of copper solution. We boil the mixture and add just
enough hydro-chloric acid to ensure a proper solution of the hydrated oxide of
aluminium. We boil or evaporate off the free hydrochloric acid and add to the
solution caustic soda or caustic potash. The caustic alkali sets free hydrated oxides of
copper and of aluminium the latter becoming dissolved when the alkali is present
in excess. We add to the liquid containing the aluminium precipitate potassium
cyanide in excess and boil the whole for a suitable period. We then add a small
quantity of potassium bicarbonate and again boil. If the solution so produced is to
be used in producing a bright deposit of alloy we add a small quantity of a solution
of hydrocyanic acid or we pass hydrocyanic gas prepared in a suitable manner into
the solution. If necessary we finally add hydrochloric acid in quantity sufficient to
render the bath neutral. The bath may then be used in the plating of metal objects

page_text: or in the depositing of the alloy upon surfaces. For this purpose a dynamo electric
machine or a battery of suitable power may be employed as most suitable or convenient
a platinum anode being used. The bath is by preference heated nearly to the boiling
point during the deposition. When the object is to obtain the alloy as a precipitate
we use the electric current to throw down the alloy without putting into the bath any
object to receive the deposit as a coating. When we wish to deposit or throw down
the aluminium alone we throw out the copper from the double cyanide solution by
adding thereto in excess a solution of sodium hyposulphite or of other suitable salt
which will precipitate the copper. The decanted solution may then be prepared to be
used as a plating bath or the aluminium may be deposited as a precipitate as in the
case of the alloy. The process may be varied to some extent the important feature
being the obtainment of the double cyanides of copper and aluminium from the
hydrated oxides of the two metals. By way of example we will describe a modification
in the process. We may add caustic soda or potash to a solution of a salt of copper
and mix with the resultant precipitate the aforesaid hydrated oxide of aluminium.
We should boil the mixture until the aluminium oxide would be dissolved and then
add potassium cyanide in excess to produce the double cyanide solution. We do not
confine ourselves to the described method of producing the chloride of copper.
Dated this 18th day of February 1887.
DUTTON & FULTON,
1,. St. James Square, Manchester,
Agents.
COMPLETE SPECIFICATION.
Improvements in the Production of Aluminium and of Alloys of
Aluminium and Copper By Electro Deposition.
We CHARLES ANTHONY BURGHARDT of King Street in the City of Manchester
County of Lancaster, Analytical Chemist, and WILLIAM JAMES TWINING of St. Bees
Street, in the same City, Electro Plater 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 :-
Our Invention has for its object to obtain aluminium and alloys of that metal with
copper, by electro-deposition, from chemical solutions. We prepare a solution
containing cyanides of the two metals, aluminium and copper, and obtain the alloy
from such solutions by electro-deposition, the alloy being produced either as a

page_text: precipitate or as a deposit upon a surface or body as in ordinary electro plating or
deposition. In the preparation of the said solution we dissolve copper with nitro-
hydrochloric acid and drive off the nitric acid by evaporating the solution to dryness,
hydro-chloric acid being added if necessary. The resultant is a slightly acid chloride
of copper. We prepare hydrated oxide of aluminium (al, O, 3 H, O) by adding an
excess of liquid ammonia to a solution of aluminium sulphate or of a suitable salt of
aluminium. We wash the precipitate to free it from foreign salts and mix it with
the aforesaid acid chloride of copper solution. We boil the mixture and add just
enough hydrochloric acid to ensure a proper solution of the hydrated oxide of
aluminium. The free hydro-chloric acid is next driven off by further evaporation.
We thus obtain a mixture which we may term a double chloride solution of copper
and aluminium.
To prepare a bath of solution containing say twenty-four ounces troy weight of metal
the ingredients would be compounded in about the following proportions. The
requisite quantity of chloride of copper is produced by treating say twenty troy
ounces of copper metal with nitro-hydrochloric acid as already set forth and the
corresponding proportion of hydrated oxide of aluminium is derived from a solution
of about thirty-two troy ounces of commercial aluminium sulphate or other suitable
salt of aluminium, this proportion being sufficient to furnish alumina equal to about
four troy ounces of aluminium. The copper chloride and aluminium oxide are
mixed, boiled and freed from excess of hydro-chloric acid by evaporation as already
set forth.
The resulting solution is now diluted with a suitable quantity of water and mixed
with about twenty-four pounds troy of solid caustic soda dissolved in water, the
mixture being gently heated for some time. The caustic soda precipitates out the
copper as hydrated oxide of copper and it also precipitates out the aluminium as
hydrated oxide of aluminium and this at once re-dissolves in the excess of caustic
soda which should be present. In order to test whether the alumina is completely
dissolved in the mixture we take a small portion of the liquor in a beaker-glass, add
an excess of cyanide of potassium thereto and heat the mixture until all of the
hydrated oxide of copper is dissolved. If the solution becomes clear on being allowed
to stand for a few minutes and shows no light coloured flocculent precipitate then the
solution contains sufficient caustic soda; but if a flocculent precipitate is seen in
quantity, then more caustic soda solution must be added to the mixture, which must
be again heated and tested with cyanide of potassium until it is apparent that the
alumina is properly dissolved. We now add to the bulk of the solution about sixteen
ounces of solid cyanide of potassium (containing about 95 per cent of potassium
cyanide) to each ounce of metal in the solution and heat the mixture until all of the
suspended hydrated oxide of copper is dissolved. We then add eight ounces of solid
bi-carbonate of potassium to each ounce of metal present in the solution and boil the
solution continuously for about 24 hours or as long as is found necessary until the
solution has cleared itself, after which it may be filtered if thought to be advisable.
When it is wished to make the solution deposit the metal in a clear and bright
condition, we add to the solution whilst cold, about half a pint of a solution of
hydro-cyanic acid gas of so called "scheele's strength" or we prepare hydro-cyanic
acid gas by any suitable means and pass the gas through the above mentioned solution
whilst it is cold. The condition of the solution can be tested from time to time to
ascertain if the bath deposits the metal in the desired bright and clear condition. In
the event of the bath becoming sluggish or the deposition of the metal being interfered
with from the excess of saline matter in the solution, which might happen after it had
been worked for some time, we might add a little more cyanide of potassium and boil
the solution again for some hours, but if the solution already contains an excess of
cyanide of potassium and carbonate of potassium, which is liable to be the case when
it has been at work for some time we consider that the addition of hydro-cyanic acid
gas solution or the passing of hydro-cyanic gas into the solution is preferable to the
addition of more cyanide of potassium. The action of the hydro-cyanic acid consists
principally in the formation of cyanide of potassium from the carbonate of potassium

page_text: a
in the solution, it being a well known fact in chemistry that cyanide of potassium in
the course of time decomposes into carbonate of potassium. Thus by the aforesaid
addition of hydrocyanic acid to the solution, we re-convert the excess of potassium
carbonate into potassium cyanide, and the bath is restored to its working condition.
A bath of the herein before described solution may be used in the plating of metal
objects or in the depositing of the alloy upon surfaces. For this purpose a dynamo
electric machine or a battery of suitable power may be employed to generate the
requisite electric current a platinum or other suitable anode being used or if found
to be suitable we might use an anode of aluminium bronze. The bath is worked at a
temperature of about 180° Fahrenheit during the deposition this being what we
consider a convenient working temperature, but if it is wished to obtain a deposit of
lighter colour we work the bath at a lower temperature. When the object is to
obtain the alloy as a precipitate we use the electric current to throw down the alloy
without putting into the bath any object to receive the deposit as a coating. The
proportions of the ingredients forming the solution hereinbefore described may be
varied, the important feature being the obtaining of the double cyanides of copper
and aluminium from the hydrated oxides of the two metals. The chloride of copper
may be produced by methods other than that herein before described.
In our
provisional specification we proposed to eliminate or throw down the aluminium
contained in the solution by the addition to the solution of a solution of sodium hypo-
sulphite or of other salt which will precipitate copper but up to the present time we
have not been successful in obtaining the pure aluminium by such means nor do we
attach importance to the method and therefore we have not included herein the
separate production of aluminium.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed we declare that what we claim is :-
(1) The obtainment of alloys of aluminium and copper by means of electricity
from solutions prepared as and in accordance with the methods hereinbefore set forth.
(2) In the electro-deposition or manufacture of alloys of aluminium and copper
the employment of a double cyanide solution prepared by dissolving alumina in a
solution of chloride of copper and treating the mixture substantially as hereinbefore
described.
(3) The employment of caustic soda or caustic potash for the purpose of causing
the aluminium and copper to combine together in the solution and thus to form double
cyanides of aluminium and copper substantially as hereinbefore described.
Dated this 20th day of July 1887.
DUTTON & FULTON,
1, St. James Square, Manchester,
Agents.