Year: 1894

page_text: Date of Application, 31st May, 1894
Complete Specification Left, 13th Feb., 1895-Accepted. 16th Mar., 1895
Where the reaction between the nitric acid and the hydrochloric acid takes
place according to the equation No. 1 the nitrous sulphuric acid (HSO,NO,) will
35 forin in accordance with equation No. 5. Where the reaction is conformable with
the equation No. 2, the nitrous sulphuric acid (HSO,NO₂) will be in accordance
with the equation No. 6.

page_text: NO and NO,Cl remain unabsorbed, or undecomposed by the concentrated
sulphuric acid, and partly pass away, through the water. When, therefore, a
combination or reaction takes place, according to the equations Nos. 3 and 4, this
will cause a loss of nitric acid, while the chloric gas obtained will be found to have
its purity impaired by combinations of nitre. These losses or this impurity, as the
case may be, sometimes attain rather considerable proportions. Where the reaction
between the hydrochloric and nitric acids is brought about according to the
equations Nos. 1 and 5, there can only be obtained in a pair of reaction chambers
a quantity of chlorine, not exceeding 66.6 per cent. of the hydrochloric acid
subjected to the action. When it is therefore desired to obtain 98 per cent. of
chlorine, it is necessary to employ four pairs of reaction chambers between which
the reaction of the HCl will be divided in the following proportions :-
But when the reaction is to take place in apparatus wherein the hydrochloric
acid, gas has to overcome a certain amount of pressure, a pure reaction will not
take place. according to any one of the four equations given. in, the first. instance,
Nos. 1 to 4, but all four reactions will occur alternately the order of,successio..
depending upon circumstances. The greater the quantity of HCl which, in an
apparatus such as this, is obtained by a reaction conformable to equation No. 2-the
more the proportion of 66 per cent. will be, exceeded in, one pair of reaction
chambers. If, therefore, it be desired to avoid, the inconvenience resulting from
the formation of NO₂C1 + N2O4, it is necessary to take care to comply with certai
conditions in the construction of the apparatus and to maintain certain pre-
determined proportions as regards the relative degrees of,,concentration. If
hydrochloric acid and nitric acid are introduced in suitable proportions into
apparatus wherein reaction takes place according to the equation No. 1, the acid
utilised should be free from nitre compounds or combinations. This is not so,
however, in reality, for the acid which runs off retains a-considerable amount of
those nitre combinations, in, the stage of oxidation of the nitrous acid in solution.
The mixture of sulphuric acid and nitric acid having been formed in accordance
with the present improved method, in the manner hereinafter, more fully to be set
forth, the acid which runs off after having been made use of, if it be further actel
upon by hydrochloric acid gas, will be found capable of absorbing a, quantity of
such hydrochloric acid gas attaining five per cent. of its weight. By heating such
acids, the hydrochloric acid gas will be caused to escape with violence and great
speed, so that after a very short space of time the acids will be quite free from
nitre combinations, and in heating it subsequently to, say, 130° Centigrade, there
will remain but a small quantity of HCI in solution.
If it be desired that, in reaction apparatus wherein the hydrochloric acid gas has
no pressure to overcome, the acid running off after having completed its work
should be free from nitre compounds, it is necessary that that acid should first be
saturated with hydrochloric acid gas, and then heated. When concentrated
sulphuric acid has decomposed a certain quantity of NOCI, that is to say, when it
contains a certain amount of HSO,NO₂, the hydrochloric acid gas will react upon
such acid in accordance with the following equation:
ON OSH (2)
HSO
NOCL
or in other words the reaction according to the equation No. 5 will be reversed.
This reaction will be all the more energetic, the less diluted or rarefied is the
hydrochloric acid gas. When it is, therefore, desired to obtain as perfect a
decomposition as possible of the NOCI formed, together with the maximum
concentration of HSO,NO2, in the vessels wherein the sulphuric acid is subjected

page_text: to the action, it is necessary so to arrange the reaction vessels of the, nitric acid
with the vessel in which the sulphuric acid reaction takes place, that the reaction
gases, which are most rich in HCI may meet the gases poorest in HSO,NO, and
vice-versa.
In view of these facts my foreign correspondents have worked out and successfully
tested the following process:-
According to this process the reaction between the sulphuric acid and the nitric
acid is carried out in apparatus in which there is no liquid pressure to be overcome,
since, as before mentioned, this is the only form of apparatus wherein a pure
reaction can be obtained in accordance with the equation No. 1 without the
objectionable formation of any NO,Cl and N,O.
The nitric acid is employed in the condition of a mixture of sulphuric acid and
nitric acid, the proportions of which mixture depend upon the composition of the
nitrous sulphuric acid from which the nitrous acid was converted or regenerated
into nitric acid.
The construction and arrangement of the apparatus in accordance with this
invention will be readily understood by reference to the accompanying drawings.
A A A A A are chambers or "towers" of clay or stoneware. They are
superposed as shown, and filled with porous acid proof material in lumps or
fragments. This series of chambers serves for the reaction to be brought about
between the hydrochloric and nitric acids.
The acid mixture to be treated is introduced in the condition of a jet or current
controllable at will into the chamber A. This acid jet is distributed among the
several apparatus, over their sectional area and traverses the series of apparatus in
the direction of the arrows.
B B B B B is a series of chambers of similar construction and arrangement
to the first mentioned chambers but made of lead, They serve for decomposing
the NOCI formed in the corresponding chambers A. This series of apparatus.
is traversed by a properly regulated current or jet of concentrated sulphuric
acid.
The chambers C1 C2 C3 C4 C5 are earthenware and similar in construction and
arrangement to the before mentioned chambers, they serve for the oxidation of the
nitrous acid formed during the reaction with a view to its conversion into nitric
acid. This series of apparatus is traversed by a suitably controlled current or jet
of water.
Hydrochloric acid gas as it comes from the sulphate furnace or from any other
source first enters the lower part of the chamber A¹. It then flows through the
chambers A and B in the direction of the arrows, entering into reaction, as it
proceeds, with the nitric acid in the chambers A and the sulphuric acid in the
chambers B according to the equations Nos. 1 and 5.
Owing to the manner in which the chambers A and B respectively are arranged
in relation to each other, the reaction gases richest in HCI are caused to meet the
sulphuric acid poorest in HSO3NO, and vice versa.
A¹ is directly connected with A. Owing to this fact the acid mixture passing
from A into A' after having been utilised, has been saturated in A with
hydrochloric acid gas. B¹ communicates direct with B. Therefore the NOCI
which has not been decomposed in B' encounters in B³ fresh concentrated sulphuric
acid with which it enters into reaction. The chloric gas produced passes from B³
into the apparatus D, which is fed with water intended to retain the HCI gas which
remains undecomposed.
The acid mixture, after having completed its action, leaves the chamber A¹ in a
state of saturation with hydrochloric acid gas, and its purity is impaired by nitre
compounds for the time being. It then enters the closed vessel F wherein it is
heated, which causes the hydrochloric acid gas to escape and all the saltpetre
combinations to separate. The gaseous mixture is conducted into the pipe which
serves to supply the apparatus with HCl gas and is consequently brought back to
the sets of apparatus A and B.

page_text: From the vessel F practically pure diluted sulphuric acid, free from nitric acid
is obtained.
From B the sulphuric acid saturated with H.S.O.N.O, passes into the closed
vessel E where it meets the nitric acid regenerated and diluted in the chambers C ;
and through coming into contact with the water of this nitric acid solution,
the H.S.ON.O, is decomposed into H,S.O, and N₂O3; the latter being then
conveyed to C.
Atmospheric air is admitted to the lower part of the chamber C¹.
Under the action of the oxygen and of the water admitted at C5, a regeneration
of the nitric acid takes place. The supply of water entering at C should be so
regulated that for about every 63 parts by weight of H2S.O, entering the
apparatus E, there are admitted into it 27 parts by weight of water. To mix the
liquid in E a current of air is employed. To expel or eliminate the last remnants
of N2O3 heating should be resorted to.
The results obtained in practice by this arrangement of the apparatus are as
follows:-
1. The three liquid currents-acid mixture, sulphuric acid and water,-need be
regulated only once.
.
2. The liquid need be raised only once, for which purpose the condition of the
acid mixture is particularly suited. But when this mixture has passed one of the
chambers of the A series, there forms in it a liquid akin in its action to aqua regia.
in elevating which much difficulty will be experienced and a considerable loss of
nitric acid would be sustained.
3. All the liquids as they pass through the apparatus, are completely confined in
closed spaces, thereby also obviating any loss of nitric acid.
4. In the chamber E there is automatically obtained an acid mixture which
should exactly correspond in its composition to the nitrous sulphuric acid from
which it is derived.
5. Owing to the fact that the nitrous sulphuric acid is decomposed by means of
diluted nitric acid, a minimum of water only is required for decomposing the nitrous
sulphuric acid and producing the acid mixture.
The same result as that which is attained by the action of the vessel F may be
accomplished by conveying heat to the chamber A, say by heating the HCI gas.
The chamber A' and A2 as well as the chambers of the C series, may be combined
in one apparatus.
The gas derived from the sulphate furnace, will form rarefied or diluted Cl gas.
From non-diluted HCI gas, non-diluted Cl gas will be obtained. The former may
be produced, for example, from liquid hydrochloric acid through the medium of
concentrated sulphuric acid..
:
For the purpose of developing a gas current of this nature, apparatus similar in
construction to the chamber F may be employed. Into that apparatus hydrochloric
acid and sulphuric acid would, in that case, have to be admitted in predetermined
quantities or currents, while a current of HCl gas, controlled at will, would escape;
and from this, when the temperature of the liquid is carried to about 130° Centigrade,
diluted sulphuric acid practically free from HCI, may be collected.
Dated this 31st day of May 1894.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.

page_text: (6) N₂O, +2 H₂SO₁ = 2 HSO,NO, + H₂O.
Where the reaction between the nitric acid and the bydrochloric acid takes
place according to the equation No. 1, nitrous sulphuric acid (HSO,NO2) will
form in accordance with equation No. 5. Where the reaction has taken place
conformably to equation No. 2, nitrous sulphuric acid will be produced in
accordance with equation No. 6.
N₂O, and NO,Ul remain unabsorbed, or undecomposed, by the concentrated
sulphuric acid, and partly pass away through the water. When, therefore, a
reaction takes place according to the equations Nos. 3 and 4, a loss of nitric acid

page_text: will be the result, while the chloric gas obtained will have its purity impaired by
nitre combinations. These losses, or impurities as the case may be, sometimes
attain rather considerable proportions. Where the reaction of the hydrochloric
and nitric acid is brought abont according to the equations Nos. 1 and 5, there can
only be obtained, in a pair of reaction chambers, a quantity of chlorine not
exceeding 66.6 per cent. of the hydrochloric acid subjected to the reaction. When
it is therefore desired to obtain, as a result of the reaction, 98 per cent. of chlorine,
it is necessary to employ four pairs of reaction chambers, between which the
reaction of the hydrochloric acid must be distributed in the following proportions:
But when the reaction is to take place in apparatus wherein the hydrochloric
acid gas has to overcome a certain amount of pressure; a pure reaction will not
take place according to any one of the first four equations (Nos. 1 to 4), but all
four reactions will set in and be more or less complete according to circumstances.
The greater the quantity of hydrochloric acid which, in apparatus such as this,
is obtained by the reaction No. 2, the more the proportion of 66 per cent. will be
exceeded in one pair of reaction chambers..
If, therefore, it be desired to avoid the inconvenience attending the formation
of NOCI and N2O4, it is necessary to comply with certain conditions in the
construction of the apparatus and to observe certain predetermined proportions of
concentration.
If hydrochloric acid and nitric acid be introduced in adequate proportions into a
chamber wherein the reaction takes place according to the equation No. 1, the acid
should, after use, be free from nitre compounds. This is not so, however, in
reality, for the acid which runs off retains in solution a considerable amount of
those nitre compounds, in the stage of oxidation of the nitrous acid.
The mixture of sulphuric acid and nitric acid having been obtained in accordance
with this process (and the composition of which is hereinafter more fully referred
to) the acid which runs off, after use, it further subjected to the action of hydro-
chloric acid. gas, will be capable of absorbing a quantity of such hydrochloric acid
gas not exceeding 5 per cent.
By heating such an acid mixture, the hydrochloric acid gas will be caused to
escape with violence, so that after the lapse of a very short space of time, the: said
acid mixture will be quite free from nitre compounds and in heating it subsequently
to say 130° Centigrade, there will remain. in it but a small quantity of hydrochloric
acid in solution.
If it be desired therefore, that, in reaction apparatus wherein the hydrochloric
acid gas has no pressure to overcome, the acid running off after having completed
its work, should be free from nitre compounds, it is necessary that such acid should
be first saturated with hydrochloric acid gas and then heated.
When concentrated sulphuric acid has decomposed a certain quantity of NOCI,
that is to say when it contains a certain amount of HSONO₂, the hydrochloric
acid gas will react upon such acid in accordance with the following equation :*
(7) HSOŽNO, + HCl = H₂SO, + NOCI,
or in other words the reaction according to the equation No. 5 will be reversed.
This reaction will be all the more energetic, the less diluted or rarefied is the
hydrochloric acid gas.
When it is, therefore, desired to obtain as perfect a decomposition as possible of
the NOCI formed, together with the maximum concentration of the HSO NO,, in
the vessels wherein the sulphuric acid is subjected to the reaction, it is necessary so
to arrange the reaction vessels of the nitric acid with or in relation to the vessels in

page_text: which the sulphuric acid reaction takes place, that the reaction gases, which are
most rich in HCl, may meet the sulphuric acid poorest in HSONO, an!
nice versa.
In view of these facts, my foreign correspondents bave devised and successfully
carried out the following process:
The reaction between the sulphuric acid and the nitric acid is carried out in
apparatus in which there is no liquid-pressure to be overcome, since, as before
mentioned, this is the only form of apparatus wherein a pure reaction can be
obtained in accordance with the equation No. 1, without the objectionable formation
of any NO,Cl and N₂O₁.
The nitric acid is employed mixed with sulphuric acid-the proportions of the
respective acids of which mixture depend upon the composition of the nitrous
sulphuric acid, from which the nitrous acid was converted, or regenerated, into
nitric acid.
66
The construction and arrangement of the apparatus in accordance with this
invention will be readily understood by reference to the accompanying diagram.
A1, A2, A, A, As, are chambers or towers "of suitable material such as clay
or stoneware. They are superposed as shown, and filled with porous acid proof
material in lumps or fragments. This series of chambers serves for the reaction
to be brought about between the hydrochloric and nitric acids.
The acid mixture to be treated is introduced in the condition of a jet or current
(controllable at will) into the chamber A¸ and is distributed among the several
chambers, over their sectional area, and traverses the series of chambers in the
direction of the arrows.
B₁, B, B, B, B₁, represent a series of chambers of similar construction and
arrangement to the first mentioned chambers, but made of lead. They are
traversed by a suitably controlled current of concentrated sulphuric acid and serve
for decomposing the NOCI formed in the corresponding chambers A₁ to Ag.
4
The chambers C₁ C, C, C₁ C, (regeneration apparatus) may be of earthenware,
and be similar in construction, and arrangement, to the before-mentioned chambers.
They serve for the oxidation of the nitrous acid formed during the reaction, with
a view to its conversion into nitric acid. These chambers are traversed by a
suitably controlled current or jet of water.
Hydrochloric acid gas, as it comes from the sulphate-furnace or from any other
source, first enters the lower part of the chamber A'. It then flows through the
chambers A to A and B to B in the direction of the arrows, entering into
reaction, as it proceeds, with the nitric acid in the chambers A¹ to A' and the
sulphuric acid in the chambers B' to B³ according to the equations Nos. 1 and 5..
Owing to the manner in which the chambers A₁ to A, and B₁ to B, respectively,
are arranged and connected in relation to each other, the reaction gases richest
in HCl are caused to meet the sulphuric acid poorest in HSO,NO,, and vice versa.
A is directly connected with A2, with the result that the acid mixture flowing
from A, to A, after use, becomes saturated with hydrochloric acid gas in A¹.
B, communicates directly with B. Therefore, the NOCI which has not been
decomposed in B₁, encounters in B, fresh concentrated sulphuric acid with which
it enters into reaction.
The chloric gas produced passes from B³ into the chamber D, which is fed with
water intended to retain the HCl gas which remains undecomposed.
The acid mixture, after having completed its action, leaves the chamber A, in a
state of saturation with hydrochloric acid gas; its purity being, for the time,
impaired by nitrogen compounds. It then enters the closed vessel F wherein it is
heated which causes the bydrochloric acid gas to escape and all the nitrogen
compounds to separate. The gaseous mixture is conducted into the pipe which
serves to supply the apparatus with HCl gas and is consequently brought back to
the sets of apparatus A and B. From the vessel F practically pure diluted
sulphuric acid, free from nitric acid, is obtained.
From B¹, the sulphuric acid saturated with HSO,NO, passes into the closed

page_text: vessel E, where it meets the nitric acid regenerated and diluted in the chambers Cr
to C, and through coming into contact with the water of this nitric acid solution,
the HSO, NO2 is decomposed into H₂SO, and N2O3; the latter being then
conveyed to C₁, into the lower part of which atmospheric air is admitted.
Under the action of the oxygen of the air and of the water admitted at Cs, a
regeneration of the nitrous acid into nitric acid takes place. The supply of water
entering at C, should be so regulated that for about every 63 parts by weight
of H₂SO, entering the apparatus E, there are admitted into it 27 parts by weight
of water. To mix the liquid in E a current of air is employed. To expel or
eliminate the last remnants of N2O3, heating should be resorted to.
The results obtained in practice by this arrangement of the, apparatus are as
follows:-
-
1. The three liquid currents, acid mixture, sulphuric acid, and water, need be
regulated only once.
2. The liquids need be raised only once, for which purpose the condition of the
acid mixture is particularly suited. But when this mixture has passed one of the
chambers of the A series, there forms in it a liquid akin in its action to aqua regia
in elevating which much difficulty would be experienced and there would be a
considerable loss of nitric acid.
3. All the liquids as they pass through the apparatus, are completely confined in
closed spaces, thereby also obviating any loss of nitric acid.
4. In the chamber E there is automatically obtained an acid mixture which
should exactly correspond in its composition to the nitrous sulphuric acid from
which it is derived.
5. Owing to the fact that the nitrous sulphuric acid is decomposed by means of
diluted nitric acid, a minimum of water only is required for decomposing th
nitrous sulphuric acid and producing the acid mixture.
The same result as that which is attained by the action of the vessel F may be
accomplished by conveying heat to the chamber A₁ say by heating the HCl gas.
The chamber A₁ may form one apparatus with A2; and the chambers of the
C series may be combined into one apparatus.
The gas derived from the sulphate furnace will form, with air, rarefied or
diluted Cl gas.
From non-diluted HCl gas, non-diluted Cl gas will be obtained.
The hydrochloric acid gas may be produced, for example, from liquid hydrochloric
acid through the medium of concentrated sulphuric acid.
For the purpose of developing a gas current of this nature, apparatus similar in
construction to the chamber F may be employed. Into that apparatus hydrochloric
acid and sulphuric acid would, in that case, have to be admitted in predetermined
quantities or currents, while a current of HCl gas, controlled at will, would escape;
and from this, when the temperature of the liquid is carried to about 130° Centi-
grade, diluted sulphuric acid, practically free from HCI may be collected.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The production of chlorine from hydrochloric acid gas and nitric acid, by
the employment of concentrated sulphuric acid, in a series, or row, of reaction
chambers, arranged, somewhat like scrubbers, one above the other, wherein the
reaction of nitric acid and hydrochloric acid takes place; a series of absorption
chambers fed with sulphuric acid being provided for the purpose of treating the
nitrous gases in such a manner that those reaction gases which for the time being
are richest in hydrochloric acid gas HCl are combined with the sulphuric acid
poorest in nitrous sulphuric acid and vice versa.
2. In the production of chlorine from hydrochloric acid gas and nitric acid by
the employment of concentrated sulphuric acid effecting the removal of the last
traces of nitrous compounds from the sulphuric acid, as it leaves the reaction
apparatus, by saturating such sulphuric acid with hydrochloric acid gas, and then

page_text: heating it, whereby the nitrous acid contained therein, is caused to escape together
with the hydrochloric acid gas, and is again conducted through the series of
apparatus.
3. In the production of chlorine from hydrochloric acid gas and nitric acid by
the employment of concentrated sulphuric acid automatically producing a mixture.
of diluted sulphuric and nitric acids (mixed in constant relative proportions) from
nitrous sulphuric acid, with the addition of a minimum quantity of water, by
causing the nitrous sulphuric acid in the decomposing chambers to be decomposed
by the regenerated acid into H₂SO, and N2O, so that the two liquids, as they run
off, (the arrangement being preferably such that they need not be again raised).
combine in a chamber E, the nitric acid in the regeneration chambers being
regenerated in such a diluted condition that the quantity of water employed in.
diluting it is just sufficient for decomposing the nitrous acid.
Dated this 13th day of February 1895.
JOHNSONS & WILLCOX,
Agents.