Improvements in the Manufacture of Chlorine.
Year: 1892

page_text: Date of Application, 29th July, 1892
Complete Specification Left, 20th Jan., 1893-Accepted, 25th Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Chlorine.
I, HENRY WESTON WALLIS, Analytical Chemist & Assayer, 8 Great Winchester
Street, London E.C. do hereby declare the nature of this invention to be as
follows:-
My invention consists in the treatment of nitro-hydrochloric acid with sulphuric
acid for the production of chlorine. I proceed as follows. I place sulphuric acid
in a still, and either drop into it from above or pass into it from below, a solution of
nitro hydrochloric acid. The greater part of the chlorine is formed & expelled at
once; but it may be necessary to apply heat to complete the expulsion of the
remainder. The expelled gases are led first through sulphuric acid, & then
through water or weak hydrochloric acid solution for purification in the usual
manner, & the isolated chlorine stored or utilized as desired. I may vary my
procedure by placing the nitro hydrochloric acid in the still, and introducing into
it the sulphuric acid, but I prefer the former alternative.
The nitro-hydrochloric acid is either the ordinary aqua regia, or that which is
prepared by the addition of hydrochloric acid to nitrate of soda.
Dated this 29th day of July 1892.
"
HENRY WESTON WALLIS.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Chlorine.
1, HENRY WESTON WALLIS, of 8 Great Winchester Street, London, 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:-
My invention consists in an improved process of manufacturing chlorine from
the three aquecus acids hydrochloric nitric and sulphuric.
I am aware that others have proposed to produce chlorine working with the
same materials, as for instance Donald in his Specification No. 62 dated
January 3rd 1887, and No. 5488 dated April 11th 1890, and Davis No. 6416 dated
April 28th 1890 and 6831 dated May 3rd 1890. I differ from both of them
collectively in this, that I alone use hydrochloric acid in the aqueous state, and I
differ from them individually in my method of after treatment for the more or less
complete conversion of the whole of the hydrochloric acid into chlorine.
My process is as follows, I cause sulphuric acid, hot or cold, and aqua regia
either as such, or nitric and aqueous hydrochloric acid without previously mixing
them so as to form aqua regia, to flow down a suitably packed tower or column so as
to produce an intimate mixture of them, with agitation and "atomization," or by
flowing in films in such a way as to readily release the chlorine formed.
thereby, or
I place sulphuric acid hot or cold in a vessel, and either drop into it from above,
or pass into it from below, a solution of nitrohydrochloric acid otherwise called
aqua regia. Or I reverse this order by placing the aqua regia in the vessel and
passing into it from above or below, sulphuric acid, hot or cold. Or I place
sulphuric and nitric acids together into the vessel and introduce into it aqua regia
or aqueous hydrochloric acid only; and as a final alternative I run all three acids
simultaneously into the vessel in due proportions.
The method I prefer however to adopt as follows, I place sulphuric acid in

page_text: a vessel hereinafter called the decomposer, and into it from above or below I
introduce hydrochloric and nitric acids, either separately but simultaneously, or
previously mixed together as aqua regia. I find agitation to be of some service,
and this is partly effected by the introduction of my liquid or liquids into the
sulphuric acid from below. Mechanical agitation further promotes the disengage-
ment of the gases. A further addition of hot sulphuric acid into the vessel when
the reaction slackens revives its activity, and it may be found efficacious to draw or
force air through the mixed liquids, both to perfect the agitation and to complete
the reaction.
Whatever procedure I adopt the after treatment of the evolved gases is the
same in all cases. Chlorine and nitrosyl chloride are the invariable products of the
decomposition. These are led through sulphuric acid contained in vessels
hereinafter called absorbers, which does not affect the chlorine but decomposes
nitrosyl chloride into nitrous vitriol and hydrochloric acid. This hydrochloric acid
may be directly recovered for re-use, but I find it advantageous to have an excess
of nitric acid either (a) before introduction into the decomposer, or (b) with the
sulphuric acid which is in the decomposer, or (c) with the sulphuric acid in the
first absorber, or in any pair of these, cir. in a and b, or in a and c, or in b and c, or
in three riz. in a and b and c. By this means the hydrochloric acid above mentioned
as undecomposed, can now be decomposed in whole or in part, as desired, according
to the quantity of additional nitric acid taken. The products of the decomposition
are the same. Finally the gas is washed with aqueous hydrochloric acid, to free it
from any oxides of chlorine that may have formed, and then with a small quantity
of water, after which it is ready for use.
In the event of accident or negligent working it might be advisable after the
chlorine gas has been washed by water to pass it through or over a suitable solid
metallic chloride such as sodium chloride etc. to free the chlorine from the last
traces of nitrous compounds.
In the process of manufacture the nitrous vitriol is denitrated by ordinary
means, and the nitric acid is recovered and used again; the sulphuric acid is also
recovered and re-used.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is,
1. The process substantially as described of manufacturing chlorine from
aqueous hydrochloric acid.
2. The process substantially as described of treating aqua regia and sulphuric
acid for the production of chlorine.
3. The partial or complete conversion (as desired) of aqueous hydrochloric
acid into chlorine by the oxidation of the generated nitrosyl chloride into
chlorine by excess of nitric acid in sulphuric acid substantially as described.
4. Freeing chlorine gas from the last traces of nitrous compounds by passing it
through or over a suitable solid chloride substantially as described.
Dated this 20th day of January 1893.
H. W. WALLIS.
W. P. Thompson & Boult,
Agents for the Applicant.