IMPROVE- MENTS IN OBTAINING CHLORINE ANd ManufacturinG BLEACHING POWDER, AND IN APPARATUS FOR THOSE PURPOSES
Year: 1871

page_text: LETTERS PATENT to William Henderson, of Glasgow, in the County
of Lanark, North Britain, Chemist, for the Invention of "IMPROVE-
MENTS IN OBTAINING CHLORINE ANd ManufacturinG BLEACHING POWDER, AND
IN APPARATUS FOR THOSE PURPOSES."
Sealed the 5th March 1872, and dated the 15th November 1871.
PROVISIONAL SPECIFICATION left by the said William Henderson
at the Office of the Commissioners of Patents, with his Petition,
on the 15th November 1871.
I, WILLIAM HENDERSON, of Glasgow, in the County of Lanark, North
Britain, Chemist, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN OBTAINING CHLORINE AND MANUFACTURING BLEACHING POWDER,
AND IN APPARATUS FOR THOSE PURPOSES," to be as follows, that is to say:―
This Invention has for its object to obtain chlorine and manufacture
bleaching powder by more economical, convenient, and easily managed
processes than what are in use or proposed for such purposes.

page_text: Numerous experiments which have led to the present Invention have
tended to show that there is no utility in using sulphate of copper or an
analogous salt in the existing process, in which certain mixtures of heated
air and gaseous hydrochloric acid are passed over extended surfaces of
burnt clay or similar porous material saturated with such salt, and have
shown that gaseous hydrochloric acid can be decomposed by passing it
over simple metallic oxides, such as peroxide of iron, the temperature
being maintained at over 400 degrees Fahrenheit.
Taking advantage of these results in carrying out the present Inven-
tion, the gaseous hydrochloric acid mixed with air is passed over bricks,
balls, pipes, or blocks of any suitable shape formed of a mixture of
peroxide of iron and as much clay or other suitable plastic material as
will impart the requisite cohesion; and the gases and materials are
maintained at a temperature over 400 degrees Fahrenheit. Instead of
iron oxide any oxide may be used that is reducible to the metallic state
by hydrogen, and forms a chloride decomposable by heated air. Or,
according to a preferable modification the process is separated into two
stages, in the first of which unmixed gaseous hydrochloric acid is passed
over the iron or other oxide until this is well charged with chlorine in
consequence of the decomposition of the hydrochloric acid, and it is
hydrogen combining with the oxygen of the oxide to form steam, and its
chlorine combining with the metal. The steam thus formed is allowed
to pass off until undecomposed hydrochloric acid is perceptible in it,
and the acid gas is then turned into another chamber or set of chambers
containing heated oxide, whilst previously dried and heated air is
admitted to the charged materials, causing the re-oxidation of the iron
and the liberation of chlorine. The processes are carried on in this way
alternately in two chambers or sets of chambers containing the iron
oxide or other materials, which are maintained at the requisite tempera-
ture by the application of external heat. It is not necessary to heat
the gaseous hydrochloric acid, as the action with it is one principally of
absorption, and takes place at a comparatively low temperature. The
improved processes thus avoid the serious difficulties of heating the acid
and of properly apportioning the admixture of air with it, thus very
much simplifying the procedure and apparatus.
The chlorine mixed with the nitrocen of the air is cooled, washed with

page_text: instead of passing the gases in the ordinary way over stationary layers
of powdered lime they are made to pass up tubes or cylinders, down
through which the powdered lime is made to pass in regular streams.
The lime is made to travel down along the tubes or cylinders by impart-
ing a suitable rotation to the tubes or to screws inside them, the speed
being regulated to suit the degree to which it is wished to impregnate
the lime with chlorine.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Henderson in the Great Seal Patent
Office on the 14th May 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HENDERSON, of Glasgow, in the County of Lanark, North Britain,
Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifteenth day of November, in the
year of our Lord One thousand eight hundred and seventy-one, in the
thirty-fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William Henderson, Her special
licence that I, the said William Henderson, my executors, adminis-
trators, and assigns, or such others as I, the said William Henderson,
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 IN OBTAINING CHLORINE AND MANUFACTURING BLEACHING POWDER,
AND IN APPARATUS FOR THOSE PURPOSES," upon the condition (amongst others)
that I, the said William Henderson, my executors or administrators, by
an 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

page_text: 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 in writing, that is to say :-
-
My said Invention has for its object to obtain chlorine and manu-
facture bleaching powder by more economical, convenient, and easily
managed processes than what are in use or proposed for such purposes.
Numerous experiments which have led to the present Invention have
tended to show that there is no utility in using sulphate of copper or any
analogous salt in the existing process, in which certain mixtures of heated
air and gaseous hydrochloric acid are passed over extended surfaces of
burnt clay or similar porous material saturated with such salt, and have
shown that gaseous hydrochloric acid can be decomposed by passing it
over simple metallic oxides, such as peroxide of iron, the temperature
being maintained at over 400 degrees Fahrenheit.
Taking advantage of these results in carrying out the present Inven-
tion, the gaseous hydrochloric acid mixed with air is passed over bricks,
balls, pipes, or blocks of any suitable shape formed of a mixture of
peroxide of iron and as much clay or other suitable plastic material as
will impart the requisite cohesion; and the gases and materials are
maintained at a temperature over 400 degrees Fahrenheit. Instead of
iron oxide any oxide may be used that is reducible to the metallic state
by hydrogen, and forms a chloride decomposable by heated air. Or
according to a preferable modification the process is separated into two
stages, in the first of which unmixed gaseous hydrochloric acid is passed
over the iron or other oxide until this is well charged with chlorine in
consequence of the decomposition of the hydrochloric acid, and its
hydrogen combining with the oxygen of the oxide to form steam, and
its chlorine combining with the metal. The steam thus formed is
allowed to pass off until undecomposed hydrochloric acid is perceptible
in it, and the acid gas is then turned into another chamber or set of
chambers containing heated oxide, whilst previously dried and heated
air is admitted to the charged materials, causing the re-oxidation of the
iron and the liberation of chlorine. The processes are carried on in this
way alternately in two chambers or sets of chambers containing the iron;
oxide or other materials, which are maintained at the requisite tempera-

page_text: ture. These chambers are by preference constructed of fire-brick, and
are heated by external fires and flues like muffle furnaces. It is not
necessary to heat the gaseous hydrochloric acid, as the action with it is
one principally of absorption, and takes place at a comparatively low
temperature. The improved processes thus avoid the serious difficulties
of heating the acid and of properly apportioning the admixture of air
with it, thus very much simplifying the procedure and apparatus.
The chlorine mixed with the nitrogen of the air is cooled, washed with
water, and conveyed to the apparatus for making bleaching powder,
which may consist of shelves or large chambers constructed in the usual
manner, as is well understood. Or instead of passing the gases in the
ordinary way over stationary layers of powdered lime, I cause them to
pass up tubes or cylinders, down through which the powdered lime is
made to pass in regular streams. The lime is made to travel down
along the tubes or cylinders by imparting a suitable rotation to the
tubes, or to screws inside them, the speed being regulated to suit the
degree to which it is wished to impregnate the lime with chlorine. The
tubes may be cylindrical or prismoidal, of about 20 inches internal
diameter, and of glazed earthenware or of iron lined with lead. Good
results are obtainable by passing the chlorine through about 40 feet of
such tubes arranged in one line or in connected tiers, and the tubes may
be placed horizontally or with an inclination of from 1 to 2 vertical in

page_text: travel by imparting rotation to the tubes or cylinders, or to screws inside
them, substantially as herein-before described.
In witness whereof, I, the said William Henderson, have hereunto
set
my
hand and seal, this Thirteenth day of May, in the year of
our Lord One thousand eight hundred and seventy-two.
W*. HENDERSON. (L.S.)