Method of Producing Solid Persulphate of Sodium.
Year: 1894

page_text: Date of Application, 22nd Aug., 1894
Complete Specification Left, 15th May, 1895-Accepted, 6th July, 1895
PROVISIONAL
SPECIFICATION.
Method of Producing Solid Persulphate of Sodium.
1, RICHARD LOEWENHERZ, of Roeterstraat, Amsterdam, in the Kingdom of
The Netherlands, Chemist of the Laboratory of the University do hereby declare
the nature of this invention to be as follows:-
The various trials made up to now to produce solid persulphate of sodium did
not meet with the desired success in consequence of the very great dissolvability
of that salt. A favourable result has now been attained, however, by means of
the method hereinafter described, said method making it possible to produce the
salt in question even on a commercial scale.
In carrying my improved method into practice, I dissolve solid persulphate of
ammonium in a strongly concentrated solution of soda-lye; 'said dissolution takes
place in spite of the concentration of the lye, and the want of an excess of water.
When dissolved, the persulphate of ammonium is converted into persulphate of
sodium, liberated ammonia.gas escaping during that time.
In consequence of the perfect absence of any excess of water or other
components (caused by the employment of concentrated lye, and of persulphate of
ammonium in solid state) there is attained a pure highly concentrated solution of
persulphate of sodium. The salt may easily. be caused to crystallize by either
treating the solution in a vacuum, or partly evaporating the water at a rather low
temperature, or adding alcohol to said solution.
The conversion takes place according to the following formula:

page_text: The persulphate of sodium possesses the property of introducing the oxidising
in bodies capable of being oxidized; the use of that salt for such oxidizing-
processes is very advantageous, in that the sulphate of sodium generated therewith
does not exert any noxious influence upon the body oxidized, and the sulphuric
acid liberated by the oxidation may again be combined with suitable bodies by the
addition of such ones, as for instance carbonate, or acetate respectively, of
sodium.
Owing to those properties, the persulphate of sodium may advantageously be
used for bleaching and titrating purposes, as well as for medical and antiseptic
. ones.
I, RICHARD LOEWENHERZ, of Roeterstraat, Amsterdam, in the Kingdom of
The Netherlands, Chemist of the Laboratory of the University 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 various trials made up to now: to produce solid persulphate of sodium did
not meet with the desired success in consequence of the very great dissolvability:
of that salt. A favourable result has now been attained, however, by means of
the method hereinafter described, said method making it possible to produce the
salt in question even on a commercial scale.
In carrying my improved method into practice, I dissolve solid persulphate of
ammonium in a strongly concentrated caustic natron-lye; said dissolution takes
place in spite of the concentration of the lye and the want of an excess of water.
When dissolved, the persulphate of ammonium is converted into 'persulphate of
sodium, liberated ammonia gas escaping during that time...
In consequence of the perfect absence of any excess of 'water or other
components (caused by the employment of concentrated lye, and of persulphate of
ammonium in solid state) there is attained a pure highly concentrated solution of
persulphate of sodium. The salt may easily be caused to crystallize by either
treating the solution in a vacuum or partly evaporating the water at a rather low
temperature, or adding alcohol to said solution.
“The conversion takes place according to the following formula :

page_text: with the solution of the sulphate of sodium. If thereafter an electric current is
sent through both those liquors, the sulphate will be .converted into the
persulphate.
The solution of the sulphate, or bisulphate may be mixed with sulphuric acid;
there is, however, no necessity for doing so, in that the sulphuric acid surrounding
the clay-cell diffuses through the walls of the same into the interior thereof. The
said solution should, as a matter of course, be neutralized from time to time..
Performing this by the addition of caustic natron would be a fault, in that heat
(causing the decomposition of the persulphate of sodium) would be evolved thereby..
Said neutralization should be effected by ladding carbonate of: soda in solid state.
There is then no heating whatever, whilst the formation of the sulphate of sodium
requisite for the continuance of the process is secured. There is, moreover,
maintained the concentration necessary for the subsequent crystallisation, and there
is, finally, secured by all that the continuity of the process. The failures of the
trials hitherto made are due to the want of continuity.
In lieu of the carbonate also another salt the acid of which is weaker than
sulphuric acid may be used.
The persulphate of sodium possesses the property of initiating the oxidation in
bodies capable of being oxidized; the use of that salt for such oxidizing-processes
is very advantageous, in that the sulphate of sodium generated therewith does not.
exert any noxious influence upon the body oxidized, and the sulphuric acid.
liberated by the oxidation may again be combined with suitable bodies by the
addition of such ones, as for instance carbonate, or acetate respectively, of sodium.
Owing to those properties, the persulphate of sodium may advantageously be
used for bleaching and titrating purposes, as well as for medical and antiseptic
In the presence of water. Na.S.O. decomposes as follows:
ones.
1
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
clain is :-
:-
1. A method of producing solid persulphate of sodium, characterized by adding
persulphate of ammonium to a concentrated caustic natron-lye, substantially as
described.
2. A method of producing solid persulphate of sodium, characterized by
dissolving solid persulphate of ammonium in a strongly concentrated caustic natron
lye, substantially as described.
3. A method of producing solid persulphate of sodium, consisting in dissolving
solid persulphate of ammonium in a strongly concentrated caustic natron-lye, and
causing the persulphate of sudium formed to crystallize, substantially as described.
4. A method of producing solid persulphate of sodium, consisting in dissolving
sulphate of sodium, introducing the solution into one of two vessels standing one
within the other, introducing sulphuric acid into the other of said two vessels, and
connecting said acid with the negative pole, said solution with the positive pole of
a source of electricity, substantially as described.
5. A method of producing solid persulphate of sodium, consisting in dissolving
sulphate of sodium, introducing the solution into a porous cell putting the latter
into another vessel, introducing sulphuric acid into the latter, and connecting said
acid with the negative pole, said solution with the positive pole of a source of
electricity, substantially as described.
6. A. method of producing solid persulphate of sodium, consisting in dissolving
sulphate of sodium, introducing the solution into one of two vessels standing one
within the other, and consisting the inner of porous, the outer of non-porous

page_text: material, introducing sulphuric acid into the other of said two vessels, connecting
said acid with the negative pole, said solution with the positive pole of a source of
electricity, and neutralizing the sulphuric acid diffusing through the wall of the
porous cell by adding solid carbonate of soda to the said solution, substantially as
"described.
Tated this 12th dor of Ma 1805
RICHARD LOEWENHERZ,.
By Geo. H. Rayner,
37 Chancery Lane, London, W.C., Agent for the Applicant.