Sodium, and Ammonium by Electrolysis.
Year: 1886

page_text: Sodium, and Ammonium by Electrolysis.
I, CAMILLE PETRI of Buchsweiler, Lower Alsace, German Empire, Doctor of
Philosophy 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 electrolysis of potassium Ferrocyanide and potassium Ferricyanide has
already been attempted, but the result has been the indefinite production of
either the Ferricyanide and prussian blue together, or only prussian.blue.
According to my present invention, the conditions of the electric current are
accurately determined under which only potassium Ferricyanide is produced, and
no prussian blue, and under which no further oxidation or destruction of the
Ferricyanide is effected.
The method of carrying out the improved process is as follows:-
The electrodes are placed in cells separated by porous partitions.
The cell of the negative electrode is filled with water while that of the positive
electrode is filled with a solution of potassium Ferrocyanide.
On passing an electric current of an electromotive force of 1.4-5·4 Volt. the
potassium Ferrocyanide at the positive electrode is converted into the Ferricyanide,
while in the cell of the negative electrode potassium hydroxide is separated, under
formation of hydrogen, and the water of the cell is converted into potash lye.
The current is passed through until all the potassium Ferrocyanide is converted
into Ferricyanide, after which the current is stopped, the solution of the Ferri-
cyanide and the potash lye are drawn off, and are each treated separately by
concentration for obtaining potassium Ferricyanide and caustic potash.
The process can however be carried on continuously, causing the Ferrocyanide
solution and the water to flow continuously into one part of the respective cells,
while the Ferricyanide solution, and potash lye flow off continuously from another
part of the cells.
If several baths are arranged in series, there must of course be provided for each
bath 14-54 Volt.
If the negative cell be filled with mercury instead of water the potassium
Ferrocyanide is converted into the Ferricyanide and potassium. The potassium
is taken up by the mercury under formation of potassium amalgam. In this case
031

page_text: also, the entire contents of the bath can be converted into the Ferricyanide solution
and potassium amalgam, or, as in the case of the use of water in the negative cell,
the process may be made continuous by admitting the Ferrocyanide solution and
mercury continuously, with a corresponding continuous discharge of the Ferri-
cyanide solution and potassium amalgam.
For the production of solid potassium Ferricyanide from the solutions of either
of the above described methods, the solution is evaporated and the salt separated
by crystallisation."
If the electrodes be placed in a solution of potassium Ferrocyanide without
porous partitions, and the current be passed through, both the reaction-products,
Ferricyanide of potassium and potassium hydroxide are obtained in mixed solution,
from which they are separated by crystallisation.
"The above described process is equally applicable for the production of Sodium
Ferricyanide and Ammonium Ferricyanide.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. The process of converting by means of electrolysis the Ferrocyanides of either
Potassium Sodium or Ammonium into the corresponding Ferricyanide combination
by the employment of a current of the electromotive force of 1.4-5.5 Volt, whereby
the said Ferricyanide combinations are produced at the positive electrode while
at the negative electrode potassium hydroxide or the corresponding sodium or
ammonium combinations are produced, the electrodes being either contained in
the same cell or in cells separated by porous partitions, substantially as herein
described.
2. In the process referred to in the preceding claim, the use of Mercury as the
negative electrode, whereby an amalgam of potassium, sodium or ammonium is
obtained, either in one and the same cell with the Ferricyanide combination or in
cells separated by porous partitions, substantially as herein described.
Dated this 2nd day of June 1886.