Improvements in the Manufacture of Chlorine.
Year: 1892

page_text: Date of Application, 15th July, 1892
Complete Specification Left, 15th May, 1893-Accepted, 15th Aug.. 1893
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Chlorine.
I, HENRY WESTON WALLIS Analytical Chemist and Assayer 8 Great
Winchester Street London E.C. do hereby declare the nature of this invention to
be as follows:-
I make a saturated solution of nitrate of soda & pass into it gaseous hydro-
chloric acid, or add aqueous hydrochloric acid to it, or the undissolved nitrate
both in proportion necessary to obtain the maximum of free chlorine-keeping
all cold. Sodium chloride is precipitated, which I remove. The mother liquor
is boiled & the evolved gases led through first sulphuric acid & then water. After
expulsion of the gases the now more or less spent liquor is utilized for dissolving
more nitrate of soda.
The hydrochloric acid solution which. was obtained when washing the mixed
gases hydrochloric acid & chlorine as stated above is utilized for dissolving more
nitrate of soda.
Dated this 15th day of July 1802
HENRY WESTON WALLIS.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Chlorine.
I, HENRY WESTON WALLIS of 8 Great Winchester Street in the City of
London, Analytical Chemist, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
This invention relates to an improved process of manufacturing chlorine, and
indirectly to a new method of forming aqua regia.
I pass gascous hydrochloric acid more or less dry, through or over a layer of
dry nitrate of a metal, or through a concentrated solution thereof. Chlorine and
nitrosyl chloride gases are evolved and are conducted through absorbers con-
taining strong sulphuric acid, which may or may not contain nitric acid, and
thence through absorbers containing weak hydrochloric acid and water respec-
tively and thence through powdered salt substantially as set forth and described
in my Patent No., 13822 dated 29th July 1892. As this Specification also fully
describes, and explains the isolation of the chlorine when once obtained, I shall
confine, the present application to the novel method or methods 1 pursue for
the first genesis of the chlorine. 1 now proceed to describe chemically what
happens.
pass dry hydrochloric acid into dry nitrate of soda sodium chloride is formed
and, nitric acid is liberated and this reaction is representable by the following
equation
NaNO, +4 HCI :
1
NaCl + HNO, + 3 HCl.
The temperature rises, and as it does so, the nitric acid set free, and the excess
0 of hydrochloric acid, both being anhydrous, react energetically and form chlorine,
nitrosyl chloride and water as follows:-

page_text: 7
liquid gets warm, chlorine and nitrosyl chloride are obtained and are conducted
away for treatment. In both these cases chlorine and nitrosyl chloride are
obtained directly.
These results are a little different in the next alternative, wherein I treat the
solid finely-powdered nitrate or a concentrated solution thereof with aqueous
hydrochloric acid of strength as high as I can economically procure.
In this
case the temperature does not rise, but on the contrary is depressed some 15° C.
or 20° C. chlorine and nitrosyl chloride are, not evolved; almost the whole of
the base is precipitated as chloride (especially so in the case of soda), and rapidly
subsides. The clear liquid is syphoned or filtered off (the latter best with an
exhaust), and we thus obtain a very pure aqua regia, which if treated with
sulphuric acid in the manner described in the former above-mentioned Patent,
evolves chlorine and nitrosyl chloride.
The proportions required both for the generation of chlorine directly and (by
this new method of making aqua regia) indirectly, may be as follows:-For
every 85 parts of pure nitrate of soda, 146 parts of anhydrous hydrochloric acid
gas, or its equivalent in aqueous solution are required; or in other words, for
one ton of pure nitrate of soda 1-718 tons of anhydrous hydrochloric acid gas,
or its equivalent in aqueous solution are required.
After the denitration of the nitrous vitriols obtained in my process the nitric
acid thereby recovered may be converted into aqua regia by the addition of
hydrochloric acid and chlorine be again obtained therefrom according to my
former Patent. It would then be only necessary to make good, losses of nitric
acid, by forming aqua regia from nitrate of soda and aqueous hydrochloric acid;
and it is in this, viz. by thus making good losses of nitric acid, that I anticipate
a large economy in my process.
By using aqua regia thus made or otherwise made, I make my process con-
tinuous, and completely denitrate my decomposing liquor at the same time; and
I proceed preferably in the following manner :-
Into stoneware vessels of convenient capacity, I introduce sulphuric acid of
medium gravity say about 140° Tw. and aqua regia, and regulate their outflow
therefrom in due proportions. The liquids meet and mix thoroughly well in
another vessel, and the evolved gases pass at once into sulphuric acid absorbers.
Having been to a great extent de-chlorinated and de-nitrated by the agitation
produced by their meeting and mixing, as well as by the de-hydrating action of
sulphuric acid, the liquors pass on into another vessel of suitable dimensions of
stoneware or lead or other suitable material. This vessel may be heated from
without or by other convenient means such as by a steam or hot-gas coil, heated
to a temperature of about 250°-270° F., the effect of which is to complete the
de-nitration and. de-chlorination of the mixed liquids (especially if hydrochloric'
acid is not in deficit), which now being reduced to dilute sulphuric acid of less
than 100° Tw. and water flow onwards to be reconcentrated to about 140° Tw.,
and are then returned to the stoneware vessel of convenient capacity first
alluded to, to be again mixed with aqua regia. The gases evolved, which now
consist of chlorine, nitrosyl chloride, and oxides of nitrogen (these last due to
the effect of de-nitration), pass by pipes surrounded with a cold water or air
condenser, into the same sulphuric acid absorbers as before mentioned, while.the
aqueous vapours condensed from the gases are passed back into the stoneware or
lead vessel containing the steam or hot-gas coil.
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
claim is :-
1. The manufacture of chlorine direct from gaseous hydrochloric acid acting
upon the solid nitrate of a metal (preferably sodium) or a concentrated solution
thereof substantially as specified.
2. In the manufacture of chlorine the formation of aqua regia from aqueous

page_text: hydrochloric acid and the solid nitrate of a metal (preferably sodium) or a
concentrated solution thereof substantially as specified.
3. The manufacture of chlorine from aqua regia formed from aqueous hydro-
chloric acid and the solid nitrate of a metal (preferably sodium) or a concen-
trated solution thereof substantially as specified.
4. The continuous process of manufacturing chlorine substantially as specified.
5. Completing the de-nitration and de-chlorination in situ of the mixed liquids
in a suitable vessel heated to the requisite temperature substantially as specified.
1002
HENRY WESTON WALLIS.
W. P. Thompson & Boult,
Agents for the Applicant.
HENRY WESTON WALLIS.
W. P. Thompson & Boult,
Agents for the Applicant.