The Manufacture of Persulphate of Sodium.
Year: 1899

page_text: Date of Application, 18th Dec., 1899-Accepted, 27th Jan., 1900
COMPLETE SPECIFICATION.
The Manufacture of Persulphate of Sodium.
I, BENJAMIN JOSEPH BARNARD MILLS, of 23, Southampton Buildings, in the
County of London, Patent Agent, do hereby declare the nature of this invention,
(a communication to me from Auguste Lumière and Louis Lumière, Manufacturers
of Photographic Materials, both of 21, Rue Saint-Victor, Lyon-Monplaisir, France,)
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:
-
In his study and experiments relative to persulphuric acid and the persul-
phates, Marshall has not succeeded in isolating the persulphate of sodium.
According to this author, the electrolysis of solutions of sulphate of sodium would
give persulphate, but the great solubility of this salt has prevented him from
isolating it.
The communicators have succeeded in preparing and isolating the persul-
phate of sodium, by treating the persulphate of barium, by the sulphate, of
sodium.
The persulphate of barium is employed in saturated solution, with it is mixed
sulphate of sodium, finely pulverized or in saturated solution. When the mix-
ture of the solutions or of the bodies in equimolecular proportions is finished,
the sulphate of barium formed is eliminated by filtering and the process is
finished by crystallization by natural evaporation, in receptacles having an
extensive surface. Small crystals of persulphate of sodium are soon deposited,
which are collected, dried and high dried at a rather low temperature.
The evaporation and drying are effected more rapidly and more certainly in
vacuo but may nevertheless be effected at the ordinary pressure and in the open
air.
Again the persulphate of barium in saturated solution can be treated with a
corresponding quantity of sulphuric acid, the mixture being intensely cooled to
obviate the decomposition of the persulphuric acid formed; there is then added
in small portions and avoiding any heating, either soda, or carbonate or bicar-
bonate of soda, either in the solid state or in a state of solution.
When the persulphuric acid is saturated it is filtered to eliminate the sul-
phate of barium then it is evaporated as before described with respect to the
preceding method.
The persulphate of sodium thus prepared is in the form of small anhydrous
crystals very soluble in water, 100 parts of water dissolving 53 parts of per-
sulphate of sodium at 25°.
It is applicable in industry as an oxidizer or discolorizer, and as an antiseptic.
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:
The preparation of persulphate of sodium by means of persulphate of barium,
by treating this body in very concentrated solution by the sulphate of sodium
or else by soda, the carbonate or the bicarbonate of soda, after a preliminary
D 077

page_text: treatment by sulphuric acid; the solutions of persulphate of sodium thus formed
being filtered and evaporated in vacuo or in the open air at only a slightly ele-
vated temperature, substantially as herein set forth.
Dated this 18th December 1899.
HARRIS & MILLS,
23, Southampton Buildings, London, W.C., Agents.