TREATING AND APPLYING 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
TREATING AND APPLYING DILUTE CHLORINE."
"IMPROVEMENTS IN
Sealed the 23rd April 1872, and dated the 26th February 1872.
PROVISIONAL SPECIFICATION left by the said Walter Weldon at the
Office of the Commissioners of Patents, with his Petition, on the
26th February 1872.
I, WALTER WELDON, of 29, The Cedars, Putney, in the County of
Surrey, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN TREATING AND APPLYING DILUTE CHLORINE," to be as follows :—
In a Provisional Specification numbered 317, and bearing date the
First day of this present month of February 1872, I have described a
process for the manufacture of chlorine which yields a portion of the
chlorine diluted by other gas or gases. Dilute chlorine not being nearly
so advantageously applicable to the purposes for which chlorine is chiefly
required as chlorine which is not diluted, the present Invention relates

page_text: to the treatment of the dilute chlorine produced by my said process, in
such wise as to convert it either into strong chlorine or into a compound
applicable instead thereof, such treatment being moreover applicable to
dilute chlorine produced in any other way.
To the end stated, I bring the dilute chlorine into contact first with
milk of lime, and afterwards with the product of the reaction of chlorine
thereupon in such wise as to obtain the nearest conveniently practicable
approximation to the product of the reaction, in presence of water, of
four equivalents of chlorine upon two equivalents of lime, producing two
equivalents of chloride of calcium and two of free hypochlorous acid,
according to the formula
I then treat the product thus obtained with hydrochloric acid, whereby
I obtain the chlorine both of the hydrochloric acid and of the hypo-
chlorous acid in the free state and undiluted.
The lime may be treated with only one half of the above prescribed
quantity of chlorine, two equivalents of lime absorbing two equivalents
of chlorine to form one equivalent of chloride of calcium and one of
hypochlorite of calcium, and this product being then treated with hydro-
chloric acid, as before.
Instead of lime any alkali or alkaline earth may be used as above, as
also may magnesia, oxide of zinc, or oxide of copper. In some cases,
and especially when using magnesia or oxide of zinc, the resulting
chloride may be decomposed by heat or by heat and steam, the oxide
being thus recovered for use again.
Instead of the above-mentioned oxides the sulphates of the same
metals may be used in solution in water, when the product will be a
mixed solution of chloride of the metal employed, acid sulphate of such
metal, and free hypochlorous acid. On treating this product with hydro-
chloric acid strong chlorine will be given off, and the solution remaining
will contain only chloride and acid sulphate, which by evaporation and
subsequent heating may be resolved into neutral sulphate and hydro-
chloric acid.
Instead of adding hydrochloric acid to a mixture containing hypo-
chlorous acid produced as above, the hypochlorous acid may be distilled
off from such mixture, and then applied by itself to the decomposition of

page_text: hydrochloric acid. Or it may be applied directly to bleaching purposes,
or to the direct production of solutions of hypochlorites, or to the pro-
duction of strong chlorine and a metallic chlorate by boiling it with a
suitable chloride.
The contact between the dilute chlorine and the body dissolved or
suspended in water, by which its partial conversion into hypochlorous
acid is effected, may best take place in a vertical tower, suitably packed,
down which the water in which the said body is dissolved or suspended
is kept trickling, while the dilute chlorine enters at the bottom, and the
other gas or gases associated with it pass out at the top.
The reaction between hydrochloric and hypochlorous acids may be
effected in a similar tower. When it takes place in a still the one acid
must be added to the other gradually.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Walter Weldon in the Great Seal Patent Office
on the 1st August 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 Twenty-sixth day of February, in the year
of our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth 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, the said Walter Weldon, my executors, administrators, and assigns,
or such others as I, the said Walter Weldon, my executors, admi-
nistrators, 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
* IMPROVEMENTS IN TREATING
Islands, and Isle of Man, an Invention for
AND APPLYING DILUTE CHLORINE," upon the condition (amongst others) that
I, the said Walter Weldon, my executors or administrators, by an

page_text: instrument in writing under my, or their, or one of their hands and
seals, should particularly 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.
instrument in writing under my, or their, or one of their hands and
seals, should particularly 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 the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof :-
1. In a Provisional Specification numbered 317, and bearing date the
First day of February in the year now current, I have described a
process for the manufacture of chlorine which yields a portion of the
chlorine diluted by other gas or gases. Dilute chlorine not being nearly
so advantageously applicable to the manufacture of bleaching powder
(which is the purpose for which chlorine is chiefly required) as chlorine
which is not diluted, my present Invention relates to and consists in the
treatment of the dilute chlorine produced by my said process in such
wise as to convert it either into strong chlorine or into a compound
which can be applied instead thereof, the said treatment being moreover
applicable also to the dilute chlorine produced by passing a mixture of
hydrochloric acid gas and air over surfaces of sulphate of copper or other
body capable of determining under such circumstances the liberation of
chlorine, and likewise to the dilute chlorine produced by treating, at a
suitable temperature, either by sulphurous acid gas and air, or by
sulphuric anhydride and air, or by sulphuric anhydride only, either a
metallic chloride, or a mixture of metallic chloride and metallic oxide,
or of metallic chloride and other body or bodies, 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 phos-
phates.
2. To this end, by one part of my said Invention I bring the dilute
chlorine produced by any of the methods above specified into contact
first with milk of lime, and afterwards with the product of the reaction
of chlorine thereupon in such wise as to obtain the nearest conveniently

page_text: 5. Another part of my said Invention consists in treating with milk
of lime the dilute chlorine produced by the processes above stated in
such wise as to fix only two equivalents of chlorine per two equivalents
of lime, and in then treating the product so obtained with hydrochloric
acid as before. The treatment of two equivalents of lime by two equiva-
lents of chlorine gives one equivalent of chloride of calcium and one of
hypochlorite of calcium, as in the first stage of the reaction set forth
above in paragraph 3, and the treatment of this product by two
equivalents of hydrochloric acid gives two equivalents of chloride of
calcium and two of strong chlorine, according to the equation,-
Ca Cl+CaO CIO+2 HCI = 2 CaCl+2 HO+2 Cl.

page_text: is represented by the following equation, in which sulphate of sodium is
put as the sulphate employed:-

page_text: may also, if preferred, be performed in a tower instead of in a still, the
said product trickling down the tower and meeting the hydrochloric
acid, which last in the state of vapour enters at the bottom of the tower.
The acid evolved from salt cake pots may thus be converted into strong
chlorine without requiring to be first condensed.
12. Instead of treating directly with hydrochloric acid a mixture con-
taining free hypochlorous acid produced under my said Invention, as
above set forth, the hypochlorous acid may be distilled off from such
mixture and applied by itself to the decomposition of hydrochloric acid.
Or it may be applied directly to bleaching purposes, or to the direct
production of solutions of hypochlorites, or to the production of strong
chlorine and a metallic chlorate by boiling it with a suitable chloride.
When the hypochlorous acid is to be so applied, it can also be formed by
treating the dilute chlorine with milk of carbonate of lime, or with
solution of carbonate of soda or potash.
•
Having now described the nature of my said Invention, and in what
manner the same is to be performed, I desire to point out in conclusion
that I do not claim as my Invention the manufacture of hypochlorous
acid by treating certain oxides and salts with strong chlorine, in presence
of water, such manufacture of hypochlorous acid having been proposed
many years ago by the present Professor Williamson, in the classical
memoir in which he announced his discovery of the reactions which take
place between chlorine and the bodies aforesaid, but that what I do claim
as my Invention is as follows:-
Firstly. The combination of the reaction of chlorine in presence of
water upon the oxides and salts above mentioned, with the reactions of
hypochlorous acid upon hydrochloric acid, of metallic hypochlorites upon
hydrochloric acid, and of hypoclorous acid upon metallic chlorides, and
the obtainment thereby, substantially as above set forth, of the new
industrial result of converting comparatively valueless dilute chlorine
into either strong chlorine or a compound which can be applied instead
thereof, and thus rendering available certain methods of manufacturing
chlorine which the dilution of the chlorine produced by them would
otherwise keep out of use.
Secondly. The application to the utilization of dilute chlorine, as
above set forth, of the reaction of chlorine upon certain oxides and salts,
1

page_text: Thirdly. The methods above described of bringing hydrochloric acid
and a solution containing hypochlorous acid, free or combined, into
contact with each other.
In witness whereof, I, the said Walter Weldon, have hereunto set
my hand and seal, this Twenty-second day of May, in the year
of our Lord One thousand eight hundred and seventy-two.