IMPROVEMENTS RELATING TO THE UTILIZATION OF DILUTE CHLORINE
Year: 1872

page_text: LETTERS PATENT to Walter Weldon, of 29, The Cedars, Putney, in
the County of Surrey, for the Invention of "IMPROVEMENTS RELATING
TO THE UTILIZATION OF DILUTE CHLORINE."
PROVISIONAL SPECIFICATION left by the said Walter Weldon at
the Office of the Commissioners of Patents, with his Petition, on the
6th July 1872.
I, WALTER WELDON, of 29, The Cedars, Putney, in the County of
Surrey, do hereby declare the nature of the said Invention for "Iм-
PROVEMENTS RELATING TO THE UTILIZATION OF DILUTE CHLORINE," to be as
follows:-
I. This Invention consists in certain improvements upon a former
Invention for which Letters Patent bearing date the 26th day of Feb-
ruary in the year now current have been granted to me.
II. The said former Invention related, and the present Invention
accordingly relates to the utilization of the dilute chlorine produced
either by the process for which Letters Patent bearing date the First

page_text: day of February in the year now current have been granted to me, or
by passing mixtures of hydrochloric acid gas and air over surfaces of
sulphate of copper or other catalytic agent, or by treating a metallic
chloride, or a mixture of a metallic chloride, or metallic chlorides with
a metallic oxide, or other body by cither sulphurous acid gas and air, or
by sulphuric anhydride and air, or by sulphuric anhydride only, or by
heating with access of air, either chloride of magnesium, chloride of
iron, or chloride of copper, or any mixture of a metallic chloride or
metallic chlorides, with a metallic sulphide or metallic sulphides, or with
a metallic sulphate or metallic sulphates, or with a metallic phosphate
or metallic phosphates.
III. One of the improvements which constitute my present Invention
consists in treating by milk of lime the dilute chlorine obtained in any
of the above processes in suchwise as to produce a mixed solution of
chloride and chlorate of calcium, and in then treating this mixed
solution by either aqueous or gaseous hydrochloric acid.
IV. Another of the improvements constituting the present Invention.
applies to that part of my former Invention aforesaid which consists in
treating dilute chlorine with milk of lime in suchwise as to produce
a mixed solution of chloride and hypochlorite of calcium, and in then
decomposing this mixed solution by aqueous or gaseous hydrochloric
acid. The said improvement consists in using in such case a con-
siderable excess of lime, or, which is the same thing, in stopping the
treatment after a certain portion of the lime has been acted upon; in
then separating by deposition and decantation that portion of the lime.
which has not been attacked by the chlorine from the resulting mixed
solution of chloride and hypochlorite of calcium, and in then treating
only the solution by hydrochloric acid, and employing the excess of lime
which has been separated from it in a subsequent operation of absorption.
of dilute chlorine.
V. Another of the improvements constituting my present Invention
consists in employing a closed still for the reaction between aqueous
hydrochloric acid and any product of the treatment of dilute chlorine
by a milk or solution of an oxide, or of a salt, and in admitting such
product into the closed still by means of a hydraulic lute. I prefer to
put the hydrochloric acid into the still first, and to add the other reagent
thereto gradually, in a more or less continuous and even stream, adding
it only at such rate as that at which it is decomposed. If that which

page_text: is being employed to react upon the hydrochloric acid is a solution of
a chlorate, the contents of the still must be heated by injection of steam
or otherwise; but for the reaction between hydrochloric acid and either
hypochlorous acid or a hypochlorite this will usually not be necessary.
VI. It is possible to work by putting the solution of chlorate, hypo-
chlorite, or free hypochlorous acid into the still first, and adding thereto
the hydrochloric acid; but in this method of working there is risk of a
decomposition in which oxygen shall be liberated, and this probably with
violent explosion.
VII. A stream of hydrochloric acid and a stream of the solution of
chlorate, hypochlorite, or hypochlorous acid may also be run into a closed
still simultaneously, the two streams being so proportioned that the
quantity of the one which enters the still in an unit of time shall be
just sufficient, or as nearly as possible so, to decompose the quantity of
the other which enters in the same time. For working in this way I
propose to use a still from which the residual product of the reaction
taking place in it may run out continuously, or if not continuously in
measure as the solutions which are to react on oach other enter it.
VIII. Among the gases and vapours diluting the chlorine, to the
treatment of which my present Invention applics, will usually be some
vapour of hydrochloric acid. This should be washed out of the mixture
of gases before commencing the treatment of the chlorine contained
therein. It will thus be obtained as a dilute aqueous solution, too weak
for most of the purposes for which aqueous hydrochloric acid is required
in the arts. It will be strong enough however for the decomposition of
the product of the treatment of dilute chlorine by a milk or solution of
an oxide or of a salt, and a part of my present Invention consists in
applying it thereto, and in similarly applying also the weak acid from
the "wash towers" in which are condensed the last portions of the acid
from salt cake roasters.
IX. For the treatment of the dilute chlorine by a milk or a solution of
an oxide or of a salt, I have recommended in the Specification of my
Patent, dated the 26th of February in the year now current, the employ-
ment of a vertical tower suitably packed with brick or otherwise, down
which the milk or solution of oxide or salt shall trickle while the dilute
chlorine enters at the bottom of the tower and passes upwards. I now
prefer to employ a series of two or more such towers, the gases which

page_text: issue from the top of the first tower being conducted to the bottom of
the interior of the second tower, and those which issue from the top of
the second tower being conducted to the bottom of the interior of the
third tower, and so on. The last tower of the series I connect with a
chimney by a suitable flue, or if a sufficient draught through the towers
be not obtainable by means of a chimney, I obtain it by means of a
mechanical aspirator. When the reaction has taken place sufficiently
completely in the first tower, I draw off the contents of that tower and I
then transfer to the first tower what was previously the charge of the
second tower, and to the second tower what was previously the charge of
the third tower, and so on, recharging the last tower of the series with
fresh milk or solution of oxide or salt. The milk or solution employed
in each tower will usually require passing through it a more or less
considerable number of times. Each tower should therefore communi-
cate with a suitable reservoir placed below it, from which its charge of
milk or solution can be pumped up to the top of the tower as often as
need be. These reservoirs should preferably be placed at successively
higher elevations, and be so connected with each other that the second
can be emptied into the first, and the third into the second, and so on by
merely opening certain cocks or valves.
X. This Invention applies equally when milk of some other oxide is
employed instead of milk of lime for the absorption of the chlorine in a
mixture of chlorine and other gases obtained as set forth in the second
paragraph above.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Walter Weldon in the Great Seal Patent Office
on the 31st December 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WALTER
WELDON, of 29, The Cedars, Putney, in the County of Surrey, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixth day of July, in the year of
our Lord One thousand eight hundred and seventy-two, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Walter Weldon, Her special licence, that I,

page_text: the said Walter Weldon, my executors, administrators, and assigns, or
such others as I, the said Walter Weldon, my executors, administrators,
and assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed, should
and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle
of Man, an Invention for "IMPROVEMENTS RELATING TO THE UTILIZATION OF
DILUTE CHLORINE," upon the condition (amongst others) that I, the said
Walter Weldon, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should par-
ticularly describe and ascertain the nature of the said Invention, and
in what manner the same was to be performed, and cause the same to
be filed in the Great Seal Patent Office within six calendar months next
and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Walter Weldon, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement.
I. The present Invention consists in certain improvements upon a
former Invention, for which Letters Patent numbered 602, and dated
the 26th of February 1872, have been granted to me.
II. The said former Invention related, and the present Invention
accordingly relates, to the utilization of the dilute chlorine produced.
cither by the process for which Letters Patent numbered 317, and bearing
date the 1st of February 1872, have been granted to me, or by passing
any mixture of bydrochloric acid gas and air over surfaces of sulphate of
copper, or other catalytic agent, or by treating a metallic chloride or any
mixture of a metallic chloride or metallic chlorides with a metallic oxide
or other body, either by sulphurous acid gas and air, or by sulphuric
anhydride and air, or by sulphuric anhydride only, or by heating with
access of air, either chloride of magnesium, chloride of iron, or chloride
of copper, or any mixture of a metallic chloride or metallic chlorides
with a metallic sulphide or metallic sulphides, or with a metallic
sulphate or metallic sulphates, or with a metallic phosphate or metallic
phosphates.
III. The present Invention consists, firstly, in treating by milk of
lime the dilute clilorine produced by any of the processes above set forth

page_text: until the milk of lime has been converted more or less completely into
a mixed solution of chlorate and chloride of calcium, and in then obtaining
strong chlorine by treating such mixed solution by either aqueous or
gaseous hydrochloric acid. Instead of milk of lime there may be used,
under this first part of the present Invention, a milk or solution of
either magnesia, baryta, strontia, soda, or potash.
IV. The present Invention consists, secondly, in using a considerable
excess of lime or other oxide when working under that part of the former
Invention, the Letters Patent for which are numbered 602, and dated
the 26th of February 1872, under which I treat dilute chlorine by milk
of lime or other oxide in suchwise as to produce a mixed solution of
chloride of calcium or other metal, and of hyphochlorite thereof, and in
then separating from such solution that portion of the lime or other
oxide which has not been attacked by the chlorine, and treating by
hydrochloric acid the solution only. The separation of the excess of
lime or other oxide from the said solution may best be performed by
subsidence and decantation; and I prefer that such excess of lime or
other oxide should be then employed in a subsequent operation of
absorption of dilute chlorine.
V. The present Invention consists, thirdly, in employing a closed
still for the reaction between aqueous hydrochloric acid and any solution,
either of a chlorate, or of a hypochlorite, or of free hypochlorous acid,
obtained by treating dilute chlorine by a milk or a solution of an oxide.
or of a salt, and of admitting the one to the other by an entrance
protected by a hydraulic lute. In performing this part of the present
Invention, I prefer to put the hydrochloric acid into the still first, and
to add the other reagent thereto gradually, in a more or less continuous
stream, and as nearly as may be at such rate only as that at which its
decomposition is effected. I can also work under this part of the present
Invention, by putting the other reagent into the still first, and adding
the hydrochloric acid thereto gradually; but in this method of working
there is risk of a decomposition in which oxygen shall be set free, and
which may take place with explosive violence. When the other reagent
is one which hydrochloric acid will not completely decompose without
the aid of heat, I either inject steam into the still in which the two
bodies are treated together, or I heat its contents by any other con-
venient means.

page_text: VI. The present Invention consists, fourthly, in running into a closed
still simultaneously a stream of aqueous hydrocloric acid and a stream
of any solution, either of a chlorate, or of a hypochlorite, or of free
hypochlorous acid, obtained by treating dilute chlorine by a milk or a
solution of an oxide or of a salt, the two streams being so proportioned,
or as nearly so as possible, that the quantity of the one which enters the
still in a unit of time shall be just sufficient to decompose the quantity
of the other which enters it in the same time. When working in this
manner I prefer to employ a still, from which the residual product of the
reaction taking place in it may run out in measure as the solutions of
the two reagents enter it. Such a still may be constructed and arranged
in the same manner as the stills for the generation of chlorine by the
reaction of mud of manganite of calcium upon aqueous hydrochloric
acid, which I have described under the name of "continuous stills," in
the Specification filed in pursuance of the conditions of Letters Patent,
numbered 732, which were granted to me on the 10th of March 1869.
VII. The present Invention consists, fifthly, in employing for the
liberation of strong chlorine from any solution, either of a chlorate, or
of a hypochlorite, or of free hypochlorous acid, obtained as twice already
aforesaid, the dilute solution of hydrochloric acid, obtained by washing
out from a mixture of chlorine and other gases obtained by any of the
processes above set forth, the vapour of hydrochloric acid, which is
ordinarily contained therein, and in similarly employing that part of the
aqueous hydrochloric acid produced in the manufacture of salt cake;
which is so dilute that it has hitherto been inapplicable to the manu-
facture of chlorine.
VIII. The present Invention consists, lastly, in employing for the
treatment of dilute chlorine by a milk or a solution of an oxide or of a
salt, in order to the obtainment of a compound from which to obtain
strong chlorine by treatment with hydrochloric acid, instead of only one
such tower, as is indicated in paragraph 10 of the Specification of my
aforesaid Invention, the Letters Patent for which are dated the 26th of
February 1872, a series of two or more such towers, and in so arranging
and working these towers that the gases which pass off from the first of
them shall be made to pass through the second, and the gases which
pass off from the second be made to pass through the third, and so on,
the gases being in each case conveyed from the top of one tower to the
bottom of the next, and that each time the charge of milk or solution

page_text: of oxide or salt treated in the first tower has absorbed sufficient chlorine,
and has accordingly been run off, the charge of the second tower shall
be transferred to the first tower, and the charge of the third to the
second, and so on, the last tower of the series being then recharged with
fresh milk or solution, as the case may be. The milk or solution
employed will usually require to pass through each tower a more or less
considerable number of times, according to the height of the towers.
Each tower should therefore communicate with a reservoir, suitably
placed below it, which shall receive the charge from the tower, and from
which the charge can be pumped or otherwise elevated to the top of the
tower as often as need be. If these reservoirs or receivers be placed at
successively higher elevations, and be suitably connected together, the
charge of the second tower can be run off from the reservoir or receiver
below that tower into the reservoir or receiver below the first tower, and
the charge of the third tower into the reservoir or receiver belonging to
the second tower, and so on, by simply opening appropriate cocks or
valves. The towers must, of course, be closed at the top, the milk or
solution entering them by openings protected by hydraulic lutes. They
may conveniently be packed with what are known as
soap bricks,"
arranged in pigeon-hole fashion, as is well understood. The last tower
of the series should be connected by a flue with either a chimney or a
mechanical aspirator.
Having now described the nature of my said Invention, and in what
manner the same is to be performed, I would have it understood that
what I claim as my Invention and desire to have secured to me by the
herein-before in part recited Letters Patents is, the improvements
relating to the utilization of dilute chlorine, which are above described.
In witness whereof, I, the said Walter Weldon, have hereunto set
my hand and seal, this Fourteenth day of December, in the
year of our Lord One thousand eight hundred and seventy-two.