Year: 1891

page_text: 6° We obtain likewise deposits of chromium in alkaline baths.
For example-We take a solution of a salt of chromium, to which we add any
organic salt, such as oxalate, tartrate, acetate, etc.
We pour into this bath a solution of an alkaline carbonate, say, ammonia.
We obtain thus a bath which gives deposits of chromium under the influence of
electricity.
7° In a solution of chrome alum, or any other salt of the sesquioxide of chromium,
we pour a solution of alkaline bicarbonate, and we obtain a violet precipitate.
On plunging into this liquor (holding in suspension this violet precipitate) the
two electrodes of a battery, we obtain a deposit of chromium at the negative pole.
8° We obtain deposits of chromium in baths of alkaline cyanides, or sulpho-
cyanides, holding in solution or suspension the oxide of chromium or cyanide of
chromium.
9° We may also obtain deposits of chromium by employing the roseo-chromic
salts, or chromo-ammoniacal compounds.
We will indicate only, as examples, the simplest of these baths.
We take the hydrated violet sesquioxide of chromium, and we dissolve it in
ammonia alone, or in a mixture of ammonia and an ammoniacal salt (such as hydro-
chlorate of ammonia, sulphate of ammonia, or other ammoniacal salt).
Under the influence of electricity, this bath gives, at the negative pole, a
magnificent deposit of chromium.
The series of chromo-ammoniacal compounds can furnish thus a considerable
number of baths suitable to deposit chromium under the influence of electricity.
10° To render all the baths above mentioned more conductive of electricity, we
find it advantageous to add thereto 10 to 15 per cent. of an alkaline sulphate, or of
a mixture of the sulphates of potash, soda, and ammonia.
11° In lieu of alkaline sulphates (and often at the same time as these), render the
baths more conductive of electricity, we employ likewise the alkaline nitrates,
phosphates, pyrophosphates, fluosilicates, borates, chlorides, sulphides, benzoates,
oxalates, tartrates, citrates, acetates, sulphites, bi-sulphites.
10 to 15 gr. chrome alum or fluosilicate of chromium ;
fluosilicate of soda, potash, or ammonia;
hydrofluosilicic or any other acid;
10 15
"
5 10
وو
وو
100
"
water.
"
We operate generally at the ordinary temperature; however, we find it often
advantageous to heat our baths, which gives us more rapid and more abundant
deposits. In certain cases we may heat our baths to such a point as to fuse the
salts that we employ.
12° In all the baths that we have just indicated, we cause the shade of the
chromium deposited to vary by mixing with these baths, one or more of the acids
that we have mentioned in another application of even date, relative to the
extraction of chromium by the aid of chromic acid.
We maintain the composition of our baths constant by means either of soluble
anodes, of convenient salts, which we dissolve therein, or by a methodical circulation
of solutions more or less concentrated.
The baths that we have just indicated can be mixed together, and the proportions
of the substances which compose them can vary within considerable limits,
according to the quantity of metal that it is desired to obtain.
Small quantities of alcohol, sugar, glycerine, or analogous organic substances,
added to these baths, produce an action favorable to the quality of the metal
deposited.
13° We obtain alloys of chromium with other metals; aluminium, copper, iron,
nickel, cobalt, tin, zinc, antimony, silver, palladium, platinum, by mixing with our
baths the salts of the metals that we wish to alloy.

page_text: Our baths being the one acid, the other alkaline, we can choose precisely the
mixture of salts which suits the best for the deposit of the alloys that we propose to
obtain.
Thus, we may mix with our baths, cyanide of chromium cyanides of other metals,
such as those of copper, zinc, silver, and to baths formed of a salt of sesquioxide of
chromium, we may mix the sulphates, chlorides, phosphates, oxalates, acetates, etc.,
of other metals.
We obtain also alloys by employing in our baths of chromium, soluble anodes of
iron, ferro-chromium, nickel, aluminium, zinc, copper, silver, etc.
14° In taking baths of copper, zinc, aluminium, nickel, lead, tin, silver, etc., and
adding thereto a certain quantity of one of the baths of chromium that we have just
indicated, we obtain deposits of copper, zinc, aluminium, nickel, which are con-
siderably ameliorated by the presence of a certain quantity of chromium, which
deposits at the same time as the principal metal.
We obtain, further, the alloys of chromium by composing the bath as
follows:-
We take the oxide of chromium, or a salt of chromium, which we dissolve in
soda, potash, or ammonia.
We add the oxide of the metal that we wish to alloy (oxide of iron, copper, lead,
silver).
These oxides dissolve perfectly. and form a bath which, under the influence of
electricity, gives an alloy of chromium with the metal that we have added.
Finally, we obtain alloys by depositing alternately superposed layers of
chromium & the metal we wish to alloy, and then melting the whole.
Dated this 31st day of December 1891.
NEWTON & SON,
Agents for the Applicants.
COMPLETE SPECIFICATION.
A Method of Extracting Chromium by the Aid of Electrolytic Baths
with a Base of Salts of Chromium.
We EMILE PLACET and JOSEPH BONNET both of 95 Boulevard Beaumarchais
Paris in the Republic of France Chemists 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 :-
The object of this invention is to obtain deposits of chromium by the aid of
electrolytic baths having a base of salts of chromium.
(1) We employ as a bath a solution of 10, 15 or 20 gr. of sulphate of chromium
to 100 gr. of water.
We add to this solution sulphuric acid till no more oxide deposits at the negative
pole.
(2) In place of sulphate of chromium we employ by preference chrome alum.
(double sulphate of chromium and potash soda or ammonia) because the chrome
alum is easier to prepare.
We also acidulate this solution by means of sulphuric acid.
(3) In lieu of sulphuric acid to acidulate the baths above mentioned we also
employ nitric phosphoric hydrochloric hydrofluosilicic acids and the organic acids
or a mixture of these acids.
I fall
ין
1 1

page_text: We heat this solution which is green till it becomes violet and we obtain a bath
which gives magnificent deposits of chromium.
(4) We employ likewise as bath a solution of alkaline chromate or bichromate.
We add to this solution any sulphate so to speak, sulphate of soda potash or
ammonia for example.
Sometimes we add also a little alcohol to render the re-action more rapid.
But it is better to add sulphate of chromium or better still chrome alum and to
compose the bath thus :-
10 to 15 gr. of alkaline chromate or bichromate.
10 15 of chrome alum.
دو
دو
100 of water.
"
In this bath in place of alkaline chromate or bichromate we may employ chromic
acid the re-action is the same but the bath is more expensive.
(5) In lieu of chrome alum in the baths above mentioned we find it sometimes
advantageous to employ the following salts of chromium the nitrate phosphate
chloride oxalate tartrate acetate citrate benzoate sulphite fluoride sulphide silicate
fluosilicate borate etc. of chromium.
(6) We obtain likewise deposits of chromium in alkaline baths.
For example, we take a solution of a salt of chromium to which we add any
organic salt such as oxalate tartrate acetate etc.
We pour into this bath a solution of an alkaline carbonate say ammonia.
We obtain thus a bath which gives deposits of chromium under the influence of
electricity.
(7) In a solution of chrome alum or any other salt of the sesquioxide of chromium
we pour a solution of alkaline bicarbonate and we obtain a violet precipitate.
On plunging into this liquor (holding in suspension this violet precipitate) the
two electrodes of a battery we obtain a deposit of chromium at the negative pole.
(8) We obtain deposits of chromium in baths of alkaline cyanides or sulpho-
cyanides holding in solution or suspension the oxide of chromium or cynanide of
chromium.
(9) Lastly we obtain deposits of chromium by employing the roseochromic salts
or chromo ammoniacal compositions.
We will indicate only as examples the simplest of these baths.
We take the hydrated violet sesquioxide of chromium and we dissolve it in
ammonia alone or in a mixture of ammonia and an ammoniacal salt (such as hydro-
chlorate of ammonia sulphate of ammonia or other ammoniacal salt).
Under the influence of electricity this bath gives at the negative pole a
magnificent deposit of chromium.
The series of chromo-ammoniacal compositions can furnish thus a considerable
number of baths suitable to deposit chromium under the influence of electricity.
(10) To render all the baths above mentioned more conductive of electricity we
find it advantageous to add thereto 10 to 15 per cent, of an alkaline sulphate or of
a mixture of the sulphates of potash soda and ammonia.
(11) In lieu of alkaline sulphates (and often at the same time as those) to render
the baths more conductive of electricity we employ likewise the alkaline nitrates
phosphates pyophosphates fluosilicates borates, chlorides sulphides benzoates oxalates
tartrates, citrates, acctates, sulphites bisulphites.
EXAMPLE.
10 to 15 gr. chrome alum or fluosilicate of chromium.
fluosilicate of soda potash or ammonia.
hydrofluosilicic or any other acid.
10 15
99
5 10
100
"
دو
وو
mater

page_text: deposits. In certain cases even we heat our baths to such a point as to fuse the
salts that we employ.
(12) In all the baths that we have just indicated we cause the shade of the
chromium deposited to vary by mixing with these baths one or more of the acids
that we have mentioned in another Patent of even date relative to the extraction of
chromium by the aid of chromic acid.
We maintain the composition of our baths constant by mears either of soluble
anodes of convenient salts which we dissolve therein or by a methodical circulation
of solutions more or less concentrated.
The baths that we have just indicated can be mixed together and the proportions
of the substances which compose them can vary within very great limits according
to the quantity of metal it is desired to obtain.
Small quantities of alcohol sugar glycerine or analogous organic substances
added to these baths produce an action favorable to the quality of the metal.
(13) We obtain alloys of chromium with other metals aluminium copper iron
nickel cobalt tin zinc antimony silver palladium platinum etc. by mixing with our
baths the salts of the metals that we wish to alloy.
Our baths being the one acid the other alkaline we can choose precisely the
mixture of salts which suits the best for the deposit of the alloys that we propose
to obtain.
We can also mix with our baths of cyanide of chromium cyanides of other metals
such as those of copper zinc silver etc.
To baths formed of salts of sesquioxide of chromium we can also mix the
sulphates chlorides phosphates oxalates acetates etc. of other metals.
We obtain also alloys by employing in our baths of chromium soluble anodes of
iron ferro chromium nickel aluminium zinc copper silver etc.
(14) By taking a bath of copper zinc aluminium nickel lead tin silver etc. and
adding thereto a certain quantity of one of the baths of chromium that we
have just indicated we obtain deposits of copper zinc aluminium nickel etc. which
are considerably ameliorated by the presence of a certain quantity of chromium
which deposits at the same time as the principal metal.
We obtain again the alloys of chromium by composing the bath as follows:
We take the oxide of chromium or a salt of chromium which we dissolve in
soda potash or ammonia.
We add the oxide of the metal that we wish to alloy (oxide of iron copper lend
silver). These oxides dissolve perfectly and form a bath which under the
influence of electricity gives an alloy of chromium with the metal that we have
added.
Finally we obtain alloys by depositing alternately superposed layers of chromium
and the metal we wish to alloy and then melting the whole.
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 :-
The employment of an electrolytic bath, having a base of salts of chromium, in
the manner and for the purpose hereinbefore indicated.
Dated this 21st day of September 1892.
NEWTON & SON,
Agents for the Applicants.