Improvements in the Production of Salts of Ferricyanogen.
Year: 1891

page_text: Date of Application, 24th Dec., 1891
Complete Specification Left, 15th Aug., 1892-Accepted. 17th Sept., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Production of Salts of Ferricyanogen.
I, ALEXANDER MELVILLE CLARK, of the firm of A. M. and Wm. Clark of
53, Chancery Lane, in the County of Middlesex, Fellow of the Chartered Institute
of Patent Agents, do hereby declare the nature of this invention (a communication
to me by the Deutsche Gold und Silber-Scheideanstalt, vormals Roessler, of
Frankfort-on-Main, through their agents Wirth and Co. of Frankfort-on-Main
aforesaid) to be as follows:-
:―
This invention relates to the manufacture of ferricyanides.
Alkaline ferricyanides such as red prussiate of potash are made by the oxidation
of the corresponding ferro-salts. This operation is attended with the disadvantage
that the ferri-salt is obtained in an impure solid or dissolved form as the product
of the oxidation is either dissolved with it, as for instance when chlorine or bromine
is employed, or if the electric current be employed caustic alkali is formed which
of course remains in solution.
The object of this invention is to produce the above mentioned salts whilst
obviating this disadvantage and it consists in performing the oxidation in the
presence of the salt of an alkaline earth whereby the oxygen used for oxidising
becomes combined with the alkaline earth metal. By this means the oxidation is
more easily effected and a superior result is obtained.
If the oxidation be effected by means of the electric current as well as with
permanganate or any other oxidizing agent which leaves no residual soluble
compounds, the ferri-salt can be at once obtained in a pure solution by simply
precipitating the small quantity of caustic earth alkali which may have passed
into solution, by means of carbonic or sulphuric acid. The alkaline earth salt of
ferro-cyanogen preferred is ferro-cyanide of calcium.
In the production of red prussiate by means of potassic permanganate, the
reaction takes place in accordance with the following equation which shows the
proportional weights :-
-
3 Ca, FeCy +7 K, FeCy. + 2 KMnO₁ =10 K,FeCy, + 2 MnO + 6 CaO.
The manganous oxide and the greater portion of the caustic lime are left
undissolved, and the small quantity of dissolved caustic lime passing through with
the filtrate may be readily separated out by means of carbonic acid. Of course a
double alkaline-earth, alkali salt of ferro cyanogen may be employed instead of the
simple alkaline earth salt thereof.
If chlorine be used as the oxidising agent the oxidation in the presence of an
alkaline earth salt proceeds more uniformly and gives a better yield if in this case
contrary to the oxidising media which in themselves leave no soluble impurities
pure liquors are not obtained.
1
1
1001
A. M. CLARK.
COMPLETE SPECIFICATION.
Improvements in the Production of Salts of Ferricyanogen.
I, ALEXANDER MELVILLE CLARK of the firm of A. M. and Wm. Clark, of
53, Chancery Lane, in the County of Middlesex, Fellow of the Chartered Institute
of Patent Agents, do hereby declare the nature of this invention (a communi-
cation to me by the Deutsche Gold und Silber-Scheideanstalt, vormals Roessler,
CD017

page_text: of Frankfort-on-Main, through their agents Wirth and Co. of Frankfort-on-Main
aforesaid) and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
This invention relates to the manufacture of ferri-cyanides.
Alkaline ferricyanides such as red prussiate of potash are made by the oxidation
of the corresponding ferro-salts. This operation is attended with the disadvantage
that the ferri-salt is obtained in an impure solid or dissolved form as the oxidising
agent is either dissolved with it, as for instance when chlorine or bromine is
employed, or if the electric current be employed caustic alkali is formed which of
course remains also in solution.
The object of this invention is to produce the above mentioned salts whilst
obviating this disadvantage and it consists in performing the oxidation in the
presence of the salt of an alkaline earth whereby the oxygen used for oxidising
becomes combined with the alkaline earth metal. By this means the oxidation is
more easily effected and a superior result is obtained.
If the oxidation be effected by means of the electric current, a permanganate or
any other oxidising agent which leaves no residual soluble compounds, the ferri-
salt can be at once obtained in a pure solution by simply precipitating the small
quantity of caustic earthy alkali which may have passed into solution, by means of
carbonic or sulphuric acid.
The alkaline earth salt preferred is ferro-cyanide of calcium.
In the production of red prussiate by means of potassic permanganate, the
reaction takes place in accordance with the following equation which shews the
proportional weights :-
3 Ca, FeCy, +7 K, FeCy. + 2 KMnO, = 10 K,FeCy. + 2 MnO + 6 CaO.
The manganous oxide and the greater portion of the caustic lime are left
undissolved and on filtering the small quantity of dissolved caustic lime passing
through with the filtrate may be readily separated out by means of carbonic acid.
Of course a double alkaline-earth-alkali salt of ferro-cyanogen may be employed
instead of the simple alkaline earth salt thereof.
If chlorine be used as the oxidising agent the oxidation in the presence of an
alkaline earth salt also proceeds more uniformly and gives a better yield even
though in this case contrary to that wherein the oxidising media are used which in
themselves leave no soluble impurities, pure liquors be not obtained.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
-
1. In the production of ferri cyanide of potassium or sodium, effecting the
oxidation of the corresponding ferro-cyanide in the presence of an alkaline earth
salt, as described.
2. In the production of ferri-cyanide of potassium or sodium as described in
Claim 1, effecting the oxidation of the corresponding ferro-salt by means of
electricity, permanganate or other oxidizing media which produce no soluble
compounds after the oxidizing process, and precipitating any dissolved oxide of
the alkaline earths remaining in the filtrate, in order to obtain the ferri-salt in pure
solution, as described.
Dated this 15th day of Angust 1892.
A. MELVILLE CLARK,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.