Improvements in the Preparation of Chromic Acid, and in the Extraction of Pure Acids from Alkaline Salts.
Year: 1892

page_text: Date of Application, 12th Dec., 1892
Complete Specification Left, 22nd Aug., 1893-Accepted, 11th Nov., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Preparation of Chromic Acid, and in the
Extraction of Pure Acids from Alkaline Salts.
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 to be as follows :-
Chromic acid prepared according to the ordinary processes, always contains
other acids, which it is difficult to eliminate, and which are harmful in the different.
applications of chromic acid.
The object of this invention is to obtain pure chromic acid by means of
electricity.
In carrying out this invention, we take a solution of an alkaline chromate or
bichromate.
In this solution we place a porous vase containing the same solution, or simply
pure water.
Into this vase, and also in the surrounding solution, we place electrodes of carbon,
platinum, or other unattackable conducting body.
We connect the positive pole of a source of electricity with the carbon in the
main body of solution, and the negative pole to the carbon of the porous vase, &
cause a current of electricity to pass.
After some time, the whole of the alkali will have passed into the porous vase,
the chromic acid remaining alone outside.
We augment the degree of concentration of the chromic acid solution, by dissolving
therein fresh crystals of alkaline chromate or bichromate, removing from time to
time the contents of the porous vase, and replacing them with pure water, or
solution, as before.
Crystallization is then produced in the ordinary manner.
We thus obtain pure chromic acid.
The separated alkali serves for treating chrome minerals, to produce alkaline
chromates.
This process may also be used for other purposes where the separation of acid
and alkali constituents is required.
This chromic acid may be used for any purposes for which it is applicable, by
reason of its purity and cheapness of production.
Dated this 19th day of December 1892.
NEWTON & SON,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in the Preparation of Chromic Acid, and in the
Extraction of Pure Acids from Alkaline Salts.
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 :-
Chromic acid prepared according to the ordinary processes always contains
other acids, which it is difficult to eliminate, and which are harmful in the different
applications of chromic acid.
The object of this invention is to obtain pure chromic acid by means of
electricity.

page_text: In carrying out this invention, we take a solution of an alkaline chromate or
bichromate.
In this solution we place a porous vase containing the same solution, or simply
pure water.
In to this vase, and also in the surrounding solution, we place electrodes of carbon,
platinum, or other unattackable conducting body.
We connect the positive pole of a source of electricity with the carbon in the
main body of solution, and the negative pole to the carbon of the porous vase, and
cause a current of electricity to pass.
After some time, the whole of the alkali will have passed into the porous vase
the side of the negative pole, the chromic acid remaining alone outside, or on the
side of the positive pole.
We augment the degree of concentration of the chromic acid solution, by dissolving
therein fresh crystals of alkaline chromate or bichromate, removing, from time to
time, the contents of the porous vase, and replacing them with pure water or
solution, as before.
Crystallisation is then produced in the ordinary manner.
We thus obtain pure chromic acid exempt from all foreign acid.
4
The separated alkali serves again for treating chrome minerals, to produce
alkaline chromates.
This process may also be used for other purposes where the separation of acid
and alkali constituents is required.
This chromic acid may be used for any purposes for which it is applicable by
reason of its purity and cheapness of production; notably for the chromatising and
deposition of chromium by the electrolytic processes described in the Specifications
of our three English Patents Nos. 22854, 22855, and 22856 of 1891, and more
especially the last mentioned; for the preparation of colours extracted from tȧr';
for the preparation of green oxides and pure salts of chromium; specially for the
preparation of alkaline bichromates and trichromates employed in photography;
for engraving upon metals and other materials; for bleaching; for mordanting,
dyeing, and printing upon fabrics, wood, and other materials; for tanning; for
medical and surgical purposes; for the destruction of microbes, and for disinfection;
for cauterisation; for the strengthening of soft and diseased tissues; for the
preparation and preservation of anatomical specimens; for the preparation of
combustible matters, explosives, etc., etc.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. The electrolytic process, above described, which permits of chromic acid
being obtained in a pure state by means of a solution of alkaline chromate or
bichromate, of an electric current producing the dissociation of a salt of chromium,
of a porous pot, and of two insoluble electrodes.
2. The application of this process to the extraction of pure acids from binary
compounds.
3. This pure chromic acid and its divers applications, notably, the extraction of
chromium by the electrolytic processes described in the Specifications of our above
mentioned Patents.
4. The use of the method above described for preparing pure chromic acid.
NEWTON & SON,
Agents for the Applicants.