Im- PROVEMENTS IN THE MANUFACTURE OF SODA AND CHLORINE
Year: 1873

page_text: LETTERS PATENT to Alexander Robertson Arrott, of Saint Helen's,
tr
in the County of Lancaster, Chemist, for the Invention of “Im-
PROVEMENTS IN THE MANUFACTURE OF SODA AND CHLORINE."
Sealed the 19th August 1873, and dated the 27th June 1873.
.
PROVISIONAL SPECIFICATION left by the said Alexander Robertson
Arrott at the Office of the Commissioners of Patents, with his
Petition, on the 27th June 1873.
I; ALEXANDER ROBERTSON ARROTT, of Saint Helen's, in the County
of Lancaster, Chemist, do hereby declare the nature of the said In-
vention for "IMPROVEMENTS IN THE MANUFACTURE OF SODA AND CHLORINE,"
to be as follows:-
This Invention has for its object the manufacture of soda and
chlorine from common salt. For this purpose I use phosphate of "
peroxide of iron and common salt, and expose this mixture at a red.

page_text: heat in a suitable furnace to the action of air or steam, or both, by
which means the common salt is decomposed, yielding in either case
phosphate of soda which I decompose by means of lime, obtaining
thereby phosphate of lime and caustic soda.
The manner in which I proceed is as follows:-I mix phosphate of
peroxide of iron with common salt in the proportion preferably of
three atoms or equivalents of common salt, or a little more to one
of phosphoric acid contained in the phosphate of iron, and I expose
this mixture to a strong red heat in a close or blind furnace, admitting
steam at same time into the furnace; or I decompose the mixture in
an open furnace, preferably heated by gas, and known as a gas furnace,
and now in common use. Muriatic acid is evolved which is condensed
in the usual manner, and phosphate of soda in mixture with peroxide
of iron remains. I dissolve out the phosphate of soda with water, the
peroxide of iron remaining insoluble. I then add lime to the solution
of phosphate of soda in sufficient quantity to precipitate the whole of
the phosphoric acid, as phosphate of lime, caustic soda remains in
solution; this separated from the phosphate of lime I evaporate, if
it be desirable to have it in the solid, state, or I carbonate the solution
and finish it as soda ash or soda crystals.
The peroxide of iron I dissolve in the muriatic acid produced, and
the resulting perchloride of iron I decompose by mixing it with the
phosphate of lime produced in the decomposition, the phosphate of
soda by lime, phosphate of peroxide of iron and chloride of calcium
are produced, the phosphate of iron separated from the chloride of
calcium I use again for the decomposition of common salt.
When I wish to produce chlorine I roast the mixture of phosphate
of iron and common salt in a close or blind furnace, admitting air
at same time, but not steam; by this means chlorine is evolved which
is used for any purpose for which chlorine is usually employed. As
this decomposition proceeds slowly, towards the end of the process I
prefer, when the decomposition has proceeded to the extent of about
two-thirds or more, to move the mixture into another furnace and
expose it to a higher temperature with admission of steam; the remaining
portion of chlorine is then separated as hydrochloric acid.

page_text: The quantity of hydrochloric acid obtained from unavoidable loss
or waste is insufficient to dissolve the whole of the lime used for the
decomposition of the phosphate of soda, even when the chlorine is
evolved as hydrochloric acid, and must be obtained from some other
source, and when chlorine is produced two-thirds or more of the acid
The quantity of hydrochloric acid obtained from unavoidable loss
or waste is insufficient to dissolve the whole of the lime used for the
decomposition of the phosphate of soda, even when the chlorine is
evolved as hydrochloric acid, and must be obtained from some other
source, and when chlorine is produced two-thirds or more of the acid
used. must be obtained from some extraneous source.
I also use phosphate of alumina for decomposition of common salt,
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filéd by the said Alexander Robertson Arrott in the Great Seal
Patent Office on the 24th December 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
ROBERTSON ARROTT, of Saint Helen's, in the County of Lancaster,
Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-seventh day of June, in the year of our
Lord One thousand eight hundred and seventy-three, in the thirty-.
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Alexander Robertson Arrott, Her special
license that I, the said Alexander Robertson Arrott, my executors,,
administrators, and assigns, or such others as I, the said Alexander
Robertson Arrott, 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 THE MANUFACTURE OF SODA AND CHLORINE,”
upon the condition (amongst others) that I; the said Alexander Robert-
son Arrott, 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: NOW KNOW YE, that I, the said Alexander Robertson Arrott, 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, that is to say :—
This Invention has for its object the manufacture of soda and
chlorine from common salt. For this purpose I use phosphate of
peroxide of iron and common salt, and expose this mixture at a red
heat in a suitable furnace to the action of air or steam, or of both,
by which means the common salt is decomposed, yielding in either
case phosphate of soda which I decompose by means of lime, obtaining
thereby phosphate of lime and caustic soda.
.
The manner in which I procced is as follows:-I mix phosphate of
peroxide of iron with common salt in the proportion preferably of
three equivalents of common salt to one of phosphoric acid contained
in the phosphate of iron, and as a small amount of common salt is
volatilised during the decomposition I find it advantageous to use
from three to five per cent. in excess of this proportion. I expose
this mixture to a strong red heat in a close or blind furnace, admitting
steam into the furnace; or I decompose the mixture in an open
furnace preferably heated by gas, known as a gas furnace, and now
in common use. I find it to be most advantageous however when
muriatic acid is to be evolved to decompose the mixture in a close
or blind furnace by steam, until about two-thirds of the salt is de-
composed as a large amount of chlorine is produced by the action
of atmospheric air during the decomposition in an open furnace.
Muriatic acid is evolved which is condensed in the ordinary manner,
and phosphate of soda in mixture with peroxide of iron remains in
the furnace. I dissolve out the phosphate of soda with water, the
peroxide of iron remaining insoluble. I then add to the solution of
phosphate of soda lime in sufficient quantity to precipitate the whole
of the phosphoric acid, as phosphate of lime, caustic soda remains in
solution, and this, separated from the phosphate of lime, I evaporate
to obtain solid caustic soda, or I carbonate it and finish as soda ash
or soda crystals.
*

page_text: place, and phosphate of peroxide of iron and chloride of calcium are
produced. The phosphate of peroxide of iron is precipitated, and after.
being washed from the solution of chloride of calcium is used to.
decompose common salt.
The decomposition of perchloride of iron, by means of the triphosphate
of lime, takes place most completely when the liquor is hot and slightly
acid, and I therefore prefer to use hot liquors.
.
The liquor will contain a small amount of phosphate, principally of
lime, in solution, and before being run to waste should be made slightly
alkaline by lime; the whole of the phosphate is thus, precipitated and
is used in further-operations.
When I wish to produce chlorine I roast the mixture of phosphate
of iron and common salt in a close or blind furnace, admitting air
at the same time. Chlorine mixed with a small quantity of muriatic
acid derived from the moisture of the air is produced, the acid I
remove by passing the chlorine through a condenser, whereby the
acid is condensed and chlorine, in a fit state for producing bleaching
powder or other purpose, passes on. As the decomposition and the
formation of chlorine proceeds slowly, when about two thirds of the
common salt is decomposed I prefer to move the mixture into another
furnace as soon as the evolution of chlorine slackens and expose it
to a higher temperatue in contact with steam, or an open furnace
is used, and this I prefer; the decomposition is completed by the
water arising from the combustion of the fuel, the chlorine in this case
being evolved in the form of muriatic acid.
The quantity of muriatic acid obtained is from unavoidable loss in-
sufficient to dissolve the whole of the lime used to decompose the
phosphate of soda, even when all the chlorine is evolved as muriatic
acid, and must be obtained from some other source, and when chlorine
is produced two-thirds or more of the quantity of acid required must
be derived from some extraneous source.
I also use phosphate of alumina in the same manner as herein

page_text: What I claim is, the means for the production of soda and chlorine
from common salt, and phosphate of the peroxide of iron and alumina,
substantially as herein described.
In witness whereof, I, the said Alexander Robertson Arrott, have
hereunto set my hand and seal, this Twenty-second day of
December, in the year of our Lord One thousand eight hundred
and seventy-three.