Manufacture or Production of Chemical Products by Electrolysis.
Year: 1896

page_text: Date of Application, 31st Aug., 1896
Complete Specification Left, 18th Feb., 1897-Accepted, 10th Apr., 1997
PROVISIONAL SPECIFICATION.
Manufacture or Production of Chemical Products by Electrolysis.
We, ENIL JOSEPH CONSTAM, of 53 Bahnhofstrasse, Zurich, Switzerland,
Chemist, and ARTHUR VON HANSEN, of 1, Dufourstrasse, Zurich, aforesaid,
Chemist, do hereby declare the nature of this invention to be as follows:-
This invention has reference to the manufacture or production of chemical
substances by electrolysing solutions of salts at temperatures below 0° C.
According thereto it has been found that on electrolysing solutions of alkaline
carbonates, including ammonium carbonate (which are saturated at a temperature
of 10° C.) at temperatures varying from -10° to -16° C., there are formed in
the vicinity of the anode, salts having strong oxidising properties, and which are
found to be viz. percarbonates of the base employed; whilst alkaline hydrates or
ammonia are or is formed at the cathode.
The salts of percarbonic acid thus produced are believed to have the general
formule
The formation of the percarbonate may be explained on the assumption that in
the bigbly concentrated solutions employed, the dissolved salts are partly
dissociated into the anions MCO, (in which M represents an alkaline metal, or
Ammoniun) and into the cations M, and that during the electrolysis, the remainder
of the molecules MCO, present in the anode spaces, combine with one another,
thus producing of the new substances, the above mentioned molecules M,C,O, viz.
percarbonates.
The invention can be carried out by placing a solution of potash for example
Faturated at 10° C. in a glass vessel and cooled to -16° C. using as a diaphragm
an earthenware or clay cell, for a cathode, sheet platinum, and for an anode,
platinum in the form of wire or sheet.
The current from say six accumulators is then passed through the solution, and
the resistance so regulated as to avoid any increase of temperature. With the
apparatus used in our experiments the strength of the current employed was about
3 amperes, the potential at the terminals of the bath being about 5 volts.
After the current has been passing for a certain time, there is deposited in the
anode space, a blueish amorphous salt which must be filtered off and dried very
quickly on account of the decomposing action of water at ordinary temperatures.

page_text: The salt thus obtained is percarbonate of potassium K,C,O, mixed with more or
less potash and potassium bicarbonate.
During the production of the new salt in the manner above described, the current
density may be allowed to vary from 1 to 300 amperes per square decimeter of
anode surface. If desired the electrolysis may also be conducted without the use
of a diaphragm.
Instead of employing platinum electrodes, electrodes of any other suitable
refractory or resisting material may be used.
Percarbonate of potassium is a powerful oxidizing agent, as are the percarbonatos
generally. When brought into contact with water at ordinary room temperature,
it gives off oxygen and some carbon dioxide. With acids it yields oxygen and
carbon dioxide, some hydrogen-peroxide being also invariably formed. With
potash lye it gives off oxygen alone. By reason of its oxidising properties,
potassium percarbonate also acts as a bleaching agent. It bleaches indigo solution
and also cotton, wool, silk, hair, feathers and like substances. It can therefore be
used as a bleaching and oxidising agent in place of potassium permanganate,
sodium-peroxide, hydrogen peroxide, ammonium per-sulphate, and similar
substances.
Dated this 21st day of Amours 1000
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.
Manufacture or Production of Chemical Products by Electrolysis.
We, EMIL JOSEPH CONSTAM, of 58 Bahnhofstrasse, Zurich, Switzerland,
Chemist, and ARTHUR VON HANSEN, of 1 Dufourstrasse, Zurich, aforesaid,
Chemist, 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 :-
It has been found that on electrolysing at temperatures below zero (as indicated
in the following description) solutions of the alkaline carbonates, including
ammonium carbonate (which are saturated at low temperatures), there are formed
in the vicinity of the anode, salts having strong oxidizing properties, and which are
found to be percarbonates of the base employed; whilst alkaline hydrates or
. ammonia are or is formed at the cathode.
The salts thus produced are believed to have the general formula :-

page_text: dissociated into the anions MCO, (in which M represents an alkaline metal, or
ammonium) and into the cations M, and that during the electrolysis, the remainder
of the molecules MCO, present in the anode spaces, combine with one another,
thus producing the above mentioned molecules of the new substances M,C,O, viz.
percarbonates.
The percarbonates thus formed in the case of sodium and of ammonium remain
in solution, becoming rapidly decomposed into bi-carbonates and oxygen. Their
existence in the solution may be proved by various reactions for instance by the
blue colouration formed with an iodide of potassium and starch solution or by the
decolourizing of an acidulated solution of potassium permanganate.
The percarbonate most easily forined is the potassium salt which can be obtained
in a solid state by placing a solution of chemically pure carbonate of potassium for
example saturated at -10° C. and cooled to -16° C. in a glass vessel using as a
diaphragm au earthenware or clay cell, for a cathode sheet platinum, and for an
anode platinum in the form of wire.
The current from say four to six accumulators is then passed through the solution,
With the
and the resistance so regulated as to avoid any increase of temperature.
apparatus used in our oxperiments the strength of the current employed was about
3 amperes, the potential at the terminals of the bath being about 8 volts.
After the current has been passing for two or three hours, there is deposited in
the anode space, a bluish amorphous salt that must be filtered off and dried very
quickly on account of the decomposing action of water at ordinary temperatures,
and which becomes white on drying.
The salt thus obtained is percarbonate of potassium K,C,O, mixed with more or
less potash and potassium bicarbonate.
During the production of the new salt in the manner above described, the
current deusity may be allowed to vary from 1 to 300 amperes per square decimeter
of anode surface; but in order to obtain a high percentage of percarbonate the
density of the current should not be below 50 amperes per square decimeter of
anode surface.
Percarbonate of potassium is an oxidizing agent, as are the percarbonates
generally. When brought into contact with water at ordinary temperatures, it
gives off oxygen and some carbon dioxide. With acids it yields peroxide of
hydrogen and carbon dioxide. With potash lyo it gives off oxygen alone. By
reason of its oxidising properties, potassium percarbonate also acts as a bleaching
agent. It bleaches indigo solution and also cotton, wool, silk, hair, feathers and
like substances. It can therefore be used as a bleaching aud oxidising agent in
place of potassium permanganate, sodium-peroxide, hydrogen peroxide, ammonium-
persulphate, and similar substances.
Having now particularly described and ascertained the nature of the said iuven-
tion and in what mauner the same is to be performed we declare that what we
claim is :-
1. The manufacture of percarbonates by electrolysing a saturated solution of a
suitable carbonate at a temperature below the freezing point of water.
2. The herein described process for the manufacture of percarbonates of the
alkali metals and of ammonium, which consists in electrolyzing a saturated solution
of a carbonate of an alkali metal or of ammonium at a temperature below the
freezing point of water.
3. As new chemical compounds, percarbonates of the alkali metals and of
ammonium having the properties bereiu described.
Dated thin 19th dow of February 1807
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.