CERTAIN IMPROVEMENTS IN THE PROCESS OF MANUFAC- TURING ALKALI FROM COMMON SALT
Year: 1838

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
WILSON, of Liverpool, in the County of Lancaster, Lecturer on Chemistry,
send greeting.
WHEREAS Her present Majesty Queen Victoria, by Her Letters Patent
under the Great Seal of the United Kingdom of Great Britain and Ireland,
bearing date at Westminster, the Twenty-second day of November now last
past, did give and grant unto me, the said John Wilson, Her especial licence,
full power, sole privilege and authority, that I, the said John Wilson, my
executors, administrators, and assigns, or such others as I, the said John
Wilson, my executors, administrators, or assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during
the term of years therein expressed, should and lawfully might make, use,
exercise, and vend, within England, Wales, and the Town of Berwick-upon-
Tweed, my Invention of "CERTAIN IMPROVEMENTS IN THE PROCESS OF MANUFAC-
TURING ALKALI FROM COMMON SALT;" in which said Letters Patent there is
contained a proviso obliging me, the said John Wilson, by an instrument in
writing under my hand and seal, particularly to describe and ascertain the
nature of my said Invention, and in what manner the same is to be performed,
and to cause the same to be inrolled in Her said Majesty's High Court of
Chancery within six calendar months next and immediately after the date
of the said recited Letters Patent, as in and by the same, reference being
thereunto had, will more fully appear..

page_text: NOW KNOW YE, that in- compliance with the said proviso, I, the said
John Wilson, do hereby declare that the nature of my said Invention, and the
manner in which the same is to be performed, is particularly described and
ascertained by the following description thereof, that is to say:-
In the usual method of decomposing common salt, by pouring sulphuric
acid upon the salt, muriatic acid gas is disengaged in great quantity, and is
with difficulty condensed on a large scale, and the sulphate of soda produced
by this process contains an. excess of .sulphuric acid, which is expelled by
roasting. Now the objects of my improvements are the following,-
First, to effect the decomposition of common salt without the disengagement
of muriatic acid gas.
"
Second, to obtain a neutral sulphate of soda without the loss of sulphuric
acid.
Thirdly, to recover the sulphur in the form of sulphuretted bydrogen, when
the sulphate of soda is decomposed, to procure alkali.
These my improvements are effected by the use of certain sulphates for
decomposing.common salt, vizt, the proto sulphate of iron, the proto sulphate
of manganese, the sulphate of magnesia, and the sulphate of lime. My
improvements are also in part effected by the use of the hydrated protoxide
of iron, and the proto carbonate of iron, also the hydrated protoxide of
manganese and the proto carbonate of manganese in decomposing the
sulphuret of sodium.
I shall now describe the manner in which I effect the several objects of
my Invention.
When I use the proto sulphate of iron to decompose common
salt I proceed as follows:-I add the salt (for this purpose I prefer the fine
grained salt) to a boiling saturated solution of the proto sulphate of iron, using
an equivalent of each, that is to say, to a saturated solution containing one
hundred and thirty-nine parts of the crystallized sulphate of iron, or seventy-six
of the anhydrous sulphate, I add about seventy parts of fine salt, but, to
ensure the entire decomposition of the sulphate of iron, I use the salt rather
in excess of the equivalents here stated. On adding the salt to the solution
of sulphate of iron mutual decomposition immediately takes place, but I
prefer allowing the mixture to boil for about a quarter of an hour. The
sulphate of soda in this process falls down in the state of fine anhydrous
crystals; these I remove (in the usual way of removing precipitates from solutions)
from the solution, which is now a chloride of iron. I allow the sulphate of soda
to drain, and then wash it with a hot saturated solution of common salt, which
removes any chloride of iron which may remain in the sulphate of soda.
Now I would have it observed, that I am aware that others have decom-

page_text: posed salt by mixing it with sulphate of iron either in a dry state or in
solution, but these decompositions have been effected by exposing the mixtures
to heat; in a furnace, in order to drive off the muriatic acid gas. What I claim
therefore as my Invention is, the mode above described, namely, adding
salt, in the state of fine crystals or powder, to a boiling saturated solution of
proto sulphate of iron, and by this means obtaining anhydrous sulphate of
soda without any disengagement of muriatic acid gas.
My next process is to convert the sulphate of soda, obtained as above
described, into sulphuret of sodium, by mixing it with about one third of its
weight of coke or slack (which I prefer to use in a ground state) and exposing
the mixture to heat either in a close or in a reverberatory furnace. When re-
moved from the furnace it is placed into lixiviating vats, where the sulphuret of
sodium is dissolved by water, and the solution allowed to run from off the
consumed carbonaceous matter into the receiver, where it is to be used in a
manner herein-after described. I next decompose the chloride of iron (obtained
by the first process) by means of the hydrate of lime, viz, into the vessel
containing the hydrate of lime in the state of cream of lime, I gradually pour-
the solution of the chloride of iron until the excess of lime is almost entirely
removed. During this operation a reaction takes place between the lime
and the chloride of iron, and the products are hydrated protoxide of iron and
chloride of calcium. I separate the chloride of calcium by washing with
abundance of water. Having thus obtained the hydrated protoxide of
iron, I add to it the solution of sulphuret of sodium (obtained as above.
described). During this operation the reaction which takes place produces
proto sulphuret of iron and caustic soda. I prefer in this process to aid
the reaction by heat, which I apply by introducing steam into the mixture.
I ascertain that the decomposition is completed by the solution having,
lost the power of blackening the salts of lead. Having separated the,
solution of soda from the precipitate, viz', the proto sulphuret of iron,
I introduce the latter into a close vessel (which I prefer to be of wood lined.
with lead), and then gradually pour sulphuric acid (of the strength .usually,
employed to decompose common salt) upon the proto sulphuret of iron. The
reaction which takes place produces sulphuretted hydrogen gas and proto:
sulphate of iron. I conduct the sulphuretted hydrogen gas by a pipe leading.
from the vessel in which it is generated into a gas holder, of the form usually.
employed in coal gas works. This suphuretted hydrogen I cause to undergo
combustion by means of burners similar to those used for burning coal gas,.
and the operation being conducted in an oven or furnace similar to one.in
which sulphur is usually burned in the manufacture of sulphuric acid, the,

page_text: sulphurous acid gas produced by the combustion of the sulphuretted hydro-
gen is converted into sulphuric acid in the usual manner.
The solution of
proto sulphate of iron produced in the above process of decomposing the
proto sulphuret of iron by sulphuric acid I concentrate by evaporation until
it becomes a saturated solution; I then employ it again to decompose common
salt in the manner herein-before described. When the proto carbonate of
iron is employed to decompose the solution of sulphuret of sodium, I procure
it by decomposing the chloride of iron by means of carbonate of lime. For this
purpose I boil the solution of the proto chloride of iron with powdered
chalk, the reaction producing proto carbonate of iron and chloride of calcium.
I wash the proto carbonate of iron to free it from the chloride of calciam, and
then employ it to decompose the solution of sulphuret of sodium, and in this
case proceed in every respect the same as when the hydrated protoxide of iron
is used. I thus obtain carbonate of soda and proto sulphuret of iron, and
then decompose the proto sulphuret of iron as herein-before described..
As to that part of my Invention which relates to the mode of obtaining the
hydrated protoxide of iron and proto carbonate of iron, and using such oxide
or proto carbonate in decomposing sulphuret of sodium, I do not confiné
myself to the use of the apparatus herein-before mentioned for effecting the
objects of this part of my Invention, as other apparatus may be employed for
such purpose; nor do I claim any privilege with respect to such apparatus,
nor the preparation of the protoxide of iron from the chloride of iron by means
of lime, nor of the proto carbonate of iron by means of carbonate of lime,
nor the mode of converting the sulphate of soda into the sulphuret of sodium.
But I do claim, as my Invention, the use of the hydrated protoxide of iron
obtained from the decomposition of the chloride of iron by means of the
hydrate of lime; and also of the proto carbonate of iron obtained from the
chloride by means of the carbonate of lime to decompose the solution of
sulphuret of sodium for the purpose of procuring soda or its carbonate. I
also claim the use of the proto sulphuret of iron obtained during this pro-
cess for producing sulphuretted hydrogen gas, and the use of the proto
sulphate of iron for again decomposing common salt, in the manner herein-
before described. When I employ the proto sulphate of manganese to deconi-
pose common salt I proceed in the same manner in every respect as above
described in using the proto sulphate of iron; that is to say, I add fine
grained salt to a boiling saturated solution of proto sulphate of manganese,
using an equivalent of each; that is to say, to a saturated solution containing
seventy-six parts of anhydrous proto sulphate of manganese I add about
seventy parts of fine salt. By this means I obtain anhydrous sulphate of soda,

page_text: as in the former case, and chloride of manganese. I decompose the chloride
of manganese by hydrate of lime in the same manner as I have described for
decomposing the chloride of iron. The hydrated protoxide of manganese thus
obtained I wash and use to decompose the solution of sulphuret of sodium, as
described in the former process. The results of the reaction in this case are
caustic soda and proto sulphuret of manganese. I decompose the sulphuret
of manganese in the manner above described for decomposing the proto
sulphuret of iron, that is to say, by pouring sulphuric acid upon the proto
sulphuret of manganese contained in a close vessel, and thus disengage
sulphuretted hydrogen gas, and produce proto sulphate of manganese. When
the proto carbonate of manganese is employed I obtain it from the chloride
of manganese by boiling it with powdered chalk or other carbonate of lime,
and proceed with this proto carbonate in every respect the same as when the
proto carbonate of iron is used. In this part of my Invention
In
do not claini
the preparation of the protoxide of manganese, nor the proto carbonate of
manganese from the solution of the chloride; but I claim the use of a
saturated solution of proto sulphate of manganese for decomposing common
salt to obtain sulphate of soda without the disengagement of muriatic acid
gas; also the use of the hydrated protoxide prepared from the chloride of
manganese by means of hydrate of lime, the proto carbonate of manganese
obtained by means of carbonate of lime for decomposing the solution of
sulphuret of sodium, and the use of the proto sulphuret of manganese for
procuring sulphuretted hydrogen gas and proto sulphate of manganese.
decomposing common salt by means of sulphuric acid and binoxide of manga-
nese, for the purpose of procuring chlorine, a mixture of proto sulphate of
manganese and sulphate of soda is obtained. When I use this residuary
sulphate of manganese it is necessary to dissolve the mixed sulphates'in hot
water, and to add hydrated protoxide of manganese to saturate the excess of
acid which always exists in the mixed sulphates which form the residuum, of
the process for preparing chlorine; I then concentrate the solution until it
becomes a saturated solution, and then add to the boiling solution an equiva-
lent of salt in the form of fine crystals or powder. I thus obtain anhydrous
sulphate of soda from the reaction of the sulphate of manganese and common
salt. The equivalent of sulphate of soda thus formed precipitates along with
the sulphate of soda which previously existed in the solution. The chloride
of manganese which remains in solution I decompose by hydrate of lime in
the manner herein-before described to obtain the hydrated protoxide of man-
ganese. The sulphate of soda obtained by this process may be decomposed by
first converting it into a sulphuret of sodium, and then decomposing the

page_text: sulphuret by the hydrated oxide of iron or of manganese; or it may be 'de-
composed in the manner now commonly in use, viz, by heating the sulphate
of soda with slack and limestone. In this part of my Invention I claim
the use of the proto sulphate of manganese contained in the residuum of the
usual process for obtaining chloride from decomposing common salt. When I
employ the sulphate of magnesia to decompose common salt, I use it as in the
former processes in the state of a boiling saturated solution, viz, to a solution
containing one hundred and 'twenty-three parts of Epsom salts I add about
seventy of common salt in the state of fine crystals or powder, and boil the
mixture for about a quarter of an hour, and in this case proceed in every
respect in the same manner as in the case of the decomposition by means of
the proto sulphate of iron, but in this process chloride of magnesium and
sulphate of soda are produced. I decompose the chloride of magnesium: by
hydrate of lime in the same manner as described for decomposing the chloride
of iron; by the reaction which takes place chloride of calcium and hydrate
of magnesia are formed. After washing the latter to free it from the chloride of
calcium, I add sulphuric acid, and thus form sulphate of magnesia, which I
employ to decompose another equivalent of common salt. The sulphate of
soda produced by this process I decompose by any of the methods herein-before
described. In this part of my Invention I do not claim the decomposition of
chloride of magnesium by hydrate of lime, but I claim the use of a saturated
solution of sulphate of magnesia to decompose common salt for the purpose
of preparing sulphate of soda without the disengagement of muriatic acid gas.
When I use the sulphate of lime to decompose common salt, I boil it in the
state of fine powder, with an equivalent of carbonate of magnesia, and an
equivalent of common salt; that is to say, to eighty-six parts of sulphate of
lime I add forty-two of carbonate of magnesia and seventy of common salt;
to these I add about five hundred parts of water, other proportions of water
may be employed, but I prefer the proportion now stated; I boil the mixture
for three or four hours, the time necessary to effect the decomposition depend-
ing on the state of the sulphate of lime; when the sulphate of lime is in the
state of a very fine powder, the decomposition is effected in a much shorter
time than when it is employed in a coarse powder. The mixture may be
boiled in an iron boiler, but I prefer putting the materials into a wooden vessel
lined with lead, and heating it by introducing steam from a boiler by means of
a pipe passing into the mixture. By the reaction which takes place carbonate
of lime is formed, which precipitates, and the supernatant solution, when con-
centrated, yields anhydrous sulphate of soda and solution of chloride of
mágnesium. I decompose the chloride of magnesium by hydrate of lime in

page_text: the manner herein-before described, and thus obtain hydrated magnesia, which
I convert into the carbonate of magnesia by passing into it a current of
carbonic acid gas, which may be procured by any of the well-known methods
of preparing carbonic acid gas. The sulphate of soda I afterwards decompose
by any of the methods herein-before described. In this part of my Invention
I claim the use of the sulphate of lime and carbonate of magnesia to decom-
pose common salt, in order to procure the sulphate of soda.
In witness whereof, I, the said John Wilson, have hereunto set my
hand and seal, this Seventeenth day of May, in the year of our Lord
One thousand eight hundred and thirty-nine.
Inrolled the Twenty-second day of May, in the year above written.