Improvement in the Manufacture of Hydrochloric Acid. a
Year: 1899

page_text: Date of Application, 6th Sept., 1899
Complete Specification Left, 30th May, 1900-Accepted. 30th June 1900
PROVISIONAL SPECIFICATION.
Improvement in the Manufacture of Hydrochloric Acid.
a
I, JASPER WETTER, Chartered Patent Agent, of 37 & 39, Essex Street, Strand,
in the County of London, do hereby declare the nature of this invention,
communication by the Harkort'sche Bergwerke und Chemische Fabriken zu
Schwelm und Harkorten, Manufacturers, of Gotha, Germany, to be as follows:-
A great number of methods have been proposed for obtaining pure and
capecially non-arsenious hydrochloric acid; the majority of them require
as a final operation the distillation of the ceid with the chemicals serving to
remove the impurities. According to Bettendorf's method, for instance, arsenic
is removed by precipitating it from the acid (which has been brought to a
specific gravity ranging between 1183 and 1123) by means of stannous chloride,
and subsequently distilling the acid (. Dingler's Polytechnic Journal 194 p. 253).
Moreover, if the precipitate produced by Bettendorf's method is not completely
filtered before distillation, the distillate will always contain arsenic.
My correspondents have discovered, that, while it is not possible to obtain
non-arsenious and chemically pure hydro-chloric acid by precipitating the arsenic
with stannous chloride in the crude acid and subsequently distilling the latter,
the desired result can be produced easily, if hydro-chloric acid in a gaseous
condition is brought in contact with a solution of a stannous compound, pre-
ferably a solution of stannous chloride, for instance by conducting the gas
through the tin solution placed in a suitable receptacle, or by conducting it into
washing towers or washing troughs upon which the solution is caused to trickle.
In this manner the stannous solution is soon saturated with hydro-chloric acid.
so that afterwards no hydro-chloric acid gas will be absorbed by the washing
liquid. By thus simply washing the gaseous hydro-chloric acid with stannous
chloride solution, it is easy, to obtain hydro-chloric acid free from arsenic,
and in case suitable raw materials are employed, to obtain pure hydro-chloric
acid.
The purification of the acid is effected most certainly and rapidly, if the
temperature of the washing liquid does not materially exceed that of the atmo-
sphere. In this manner the gaseous hydro-chloric acid may be completely
relieved of arsenic, chlorine, iron and other impurities by a single operation,
so as to yield on condensation a chemically pure acid.
Dated th
eth
1000
Improvement in the Manufacture of Hydrochloric Acid.
I, JASPER WETTER, Chartered Patent Agent, of 37 & 39, Essex Street, Strand,
in the County of London, do hereby declare the nature of this invention, (a
[Price 8d.]
4

page_text: communication by the Harkort'sche Bergwerke und Chemische Fabriken zu
Schwelm und Harkorten, Manufacturers, of Gotha, Germany), and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement:-
-
A great number of methods have been proposed for obtaining pure and
especially non-arsenious hydrochloric acid; the majority of them require as
a final operation the distillation of the acid after treatment of the same with
the chemicals serving to remove the impurities. According to Bettendorf's
method, for instance, arsenic is removed by precipitating it from the acid (which
has been brought to a specific gravity ranging between 1.183 to 1.123) by
means of stannous chloride and subsequently distilling the acid (. Dingler's
Polytechnic Journal 194 p. 253).
According to Hager (Wagner's Jahresbericht f. 1872 p. 263; 1886, p. 301),
Bettendorf's process has, however, the defect that the acid treated with it always
contains tin, because the stannic chloride arising from the precipitation of the
arsenic with stannous chloride passes into the distillate. This fact has been
observed also by Lehmann (Pharm. Zeitung 34 p. 274).
Moreover, if the precipitate produced by Bettendorf's method is not com-
pletely filtered before distillation, the distillate (according to Hager) will always
contain arsenic.
My correspondents have discovered, that, while it is not possible to obtain
non-arsenious and chemically pure hydro-chloric acid by precipitating the arsenic
with stannous chloride in the crude acid and subsequently distilling the latter,
the desired result can be produced easily, if hydro-chloric acid in a gaseous
condition is brought in contact with a solution of a stannous compound, pre-
ferably a solution of stannous chloride, for instance, by conducting the gas
through the tin-solution placed in a suitable receptacle, or by conducting it into
washing towers or washing troughs upon which the solution is caused to trickle.
In this manner the stannous solution is soon saturated with hydro-chloric acid,
so that afterwards no hydro-chloric acid gas will be absorbed by the washing
liquid. By thus simply washing the gaseous hydro-chloric acid with stannous
chloride solution, it is easy, to obtain hydro-chloric acid free from arsenic,
and in case suitable raw materials are employed, to obtain chemically pure
hydro-chloric acid.
The purification of the acid is effected most certainly and rapidly, if the
temperature of the washing liquid does not materially exceed that of the atmo-
sphere. In this manner the gaseous hydrochloric acid may be completely
relieved of arsenic, chlorine, iron and other impurities by a single operation,
so as to yield on condensation a chemically pure acid.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is:
The process for obtaining pure, and especially non-arsenious, hydro-chloric
acid from crude hydro-chloric acid, which consists in treating the crude acid in
a gaseous condition with a solution of stannous chloride or solutions of other
stannous salts, substantially as described.
1
1000
FAIRFAX & WETTER,
Agents, 37 and 39, Essex Street, Strand, London.