IMPROVE- MENTS IN THE MANUFACTURE OF SODA AND POTASH, AND OF THEIR CARBONATES
Year: 1862

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, and of 166, Buchanan Street, in the City
of Glasgow, North Britain, Gentleman, for the Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF SODA AND POTASH, AND OF THEIR CARBONATES."
-A communication from abroad by Charles Louis Pierre Burton, of
45, Rue St. Sebastien, Paris, in the Empire of France.
Sealed the 25th July 1862, and dated the 6th May 1862.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson,
at the Office of the Commissioners of Patents, with his Petition, on the
6th May 1862.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, and of 166, Buchanan Street, in the City of Glasgow, North
Britain, Gentlenian, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF SODA AND POTASH, AND OF THEIR
CARBONATES," a communication from abroad by Charles Louis Pierre Burton,
of 45, Rue St. Sebastien, Paris, in the Empire of France, to be as follows:-
This Invention consists, firstly, in mixing natural or artificial sulphate of
soda, obtained either by the decomposition of marine salt, chloride of sodium,
by sulphuric acid, or by means of sulphate of iron, with about 35 per cent.
by weight of powdered charcoal, or its equivalent of coal anthracite, or other
suitable reducing organic substance; and then, subjecting this mixture to a
red heat, either in closed vessels or in a reverberatory furnace, under the

page_text: influence of a reducing flame. The mixture is maintained at an elevated
temperature, so long as carbonic oxide is disengaged. When this ceases to
be produced, and when the sulphate is completely transformed into a sulphuret,
the operation is discontinued, and the mixture is allowed to cool, care being
taken to exclude the air therefrom, and to prevent the formation of the
Lyposulphite of soda. The fused mass is then treated with hot water in
order to dissolve the alkaline sulphuret, and to separate it from the excess of
charcoal requisite for ensuring the complete reduction of the sulphate of soda.
In carrying out this operation arrangements must of course be made for
effecting a thorough lixiviation or washing, and obtaining concentrated solutions
or liquors. The third and last operation consists in subjecting the concen-
trated solutions or liquors to a boiling temperature for about 30 minutes,
with some desulphurising agent, which shall combine with, and render
insoluble, all the sulphur of the sulphuret, whilst, at the same time, it pro-
duces its equivalent quantity of soluble caustic soda in a pure state, should the
processes have been properly carried out. The sulphuretted compound produced
by the reaction above referred to having been perfectly washed and dried is
placed in communication with what is known as a leaden chamber for the
manufacture of sulphuric acid upon a plate of cast iron, which is heated in
order to burn or roast the compound, so that it may throw off the sulphur in
the form of sulphurous acid, which may be directed through the leaden
chamber and may be transformed into sulphuric acid. After this roasting the
compound becomes revivified, that is to say, it has entirely regained its
desulphurising properties. This property is not, however, confined to a single
compound or metallic oxide, but is possessed by certain other metallic oxides,
carbonates, or hydrates which, under a greater or less pressure, become
sulphuretted at the expence of the sulphur contained in the alkaline sulphurets,
which are placed in their presence. The oxide of iron, in its native condition,
may be employed in the decomposition of sulphuret of sodium, but according
to the state of aggregation of this body, the reaction will take place at the
ordinary pressure, or at a higher pressure, which may be obtained by boiling
in closed vessels and at an elevated temperature. It sometimes happens that
when oxide of iron, either native or artificial, is employed for the abstraction
of the sulphur from the solutions before mentioned, that the sulphuret
formed has a tendency to oxidize and to form certain sulphates of iron. This
inconvenience may be obviated by the employment of oxide of copper, which
I employ by preference, more especially as the desulphurization of the solution
is more easily and perfectly accomplished. My improvements further consists
in the employment not only of the oxides of the several metals which are

page_text: capable of combining with and of abstracting the sulphur from alkaline
sulphides in solutions, but in the employment of carbonates of the metallic
oxides, and I find that the desulphurising of solutions as herein mentioned,
may be effected sometimes more advantageously, when the said decomposition
is effected is closed vessels under pressures and at an elevated temperature.
The solution of caustic soda or of carbonate of soda, resulting from the before-
mentioned operations may be concentrated or may at once be employed in the
arts. These improvements, which have reference to the production of soda and
of carbonate of soda, from sulphate of soda, are also applicable to the pro-
duction of caustic potash and of carbonate of potash from the sulphato of
potash.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Henry Johnson in the Great Seal Patent Office on
the 6th November 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, Jons
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
and of 166, Buchanan Street, in the City of Glasgow, North Britain,
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixth day of May, in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-fifth year of
Her reign, did, for Herself, Ifer heirs and successors, give and grant unto me.
the said John Henry Johnson, Her special license that I,. the said John
Henry Johnson, my executors, administrators, and assigns, or such others
as I, the said John Henry Johnson, 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 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 POTASK, AND OF THEIR CAR-
BONATES," a communication from abroad by Charles Louis Pierre Burton, of
45, Rue Saint Sebastien, Paris, in the Empire of France, upon the condition
(amongst others) that I, the said John Henry Johnson, my executors or
administrators, by an instrument in writing under my hand and seal, or under
the hand and seal of one of them, should particularly describe and ascertain
the nature of the said Invention; and in what manner the same was to be

page_text: 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 John Henry Johnson, 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 :-
The said Invention consists, firstly, in mixing natural. or artificial sulphate
of soda, obtained either by the decomposition of marine salt, chloride
of sodium by sulphuric acid or by means of sulphate of iron, with about
thirty-five per cent. by weight of powdered charcoal or its equivalent of coal
anthracite, or other suitable reducing organic substance; and then, subjecting
this mixture to a red heat, either in closed vessels or in a reverberatory furnace,
under the influence of a reducing flame. The hearth of such furnace should
be composed of cast iron coated with copper or with zinc, as the employment
of fire-brick or earthly matter, renders the process impracticable by reason of
the energetic action of the alkaline sulphides upon alumina, silica, and argil-
laceous substances. The mixture is maintained at an elevated temperature,
so long as carbonic oxide is disengaged. When this ceases to be produced,
and when the sulphate is completely transformed into a sulphuret, the opera-
tion is discontinued and the mixture is allowed to cool, care being taken to
exclude the air therefrom, and to prevent the formation of the hyposulphite of
soda. The fused mass is then treated with hot water, in order to dissolve the
alkaline sulphuret and to separate it from the excess of charcoal, which has
been requisite for ensuring the complete reduction of the sulphate of soda.
In carrying out this operation arrangements must of course be made for
effecting a thorough lixiviation or washing, and obtaining concentrated
solutions or liquors. The third and last operation consists in subjecting the
concentrated solutions or liquors to a boiling temperature for about thirty
minutes with some desulphurising agent, which shall combine with and render
insoluble all the sulphur composing the sulphuret, whilst at the same time it
produces its equivalent quantity of soluble caustic soda in a pure state, should
these processes have been properly carried out. The sulphureted compound
produced by the reaction above referred to, having been perfectly washed and
dried, is placed in communication with what is known as a leaden chamber for
the manufacture of sulphuric acid upon a plate of cast iron, which is heated
in order to burn or roast the compound, so that it may throw off the combined
sulphur in the form of sulphurous acid, which may be directed through the
leaden chamber and may be transformed into sulphuric acid. After this

page_text: roasting the compound becomes revivified, that is.to say, it has entirely regained
its desulphurising properties. This property is not however confined to a
single compound or metallic oxide, but is possessed by certain other metallic
oxides, carbonates, or hydrates which, under a greater or less pressure in con-
junction with the before-mentioned. soluble sulphurets, become sulphureted at
the expense of the sulphur contained in the alkaline sulphurets which are
placed in their presence. The oxide of iron in its native condition may be
employed for the decomposition of sulphuret of sodium, but according to the
state of aggregation of this body, the reaction will take place at the ordinary
pressure or at a higher pressure, which may be obtained by boiling in closed
vessels, and at an elevated temperature. It sometimes happens that when
oxide of iron, either natural or artificial, is employed for the abstraction of the
sulphur from the solutions before-mentioned, that the sulphuret formed has a
tendency to oxidize and to form certain sulphates of iron. This inconvenience
may be obviated by the employment of oxide of copper, which I employ by
preference, more especially, as the desulphurization of the solution. The
oxide of copper may be obtained commercially by decomposing one equivalent
of sulphate of copper, obtained by roasting copper pyrites with one equivalent
of nitrate of soda or potash, whereby a soluble sulphate of soda or potash is
obtained. The finely divided insoluble oxide of copper is easily separated.
The operation being carried on in connection with a leaden chamber, the
nitrous vapours are directed through such chamber and serve for the manu-
facture of sulphuric acid. On boiling the oxide of copper obtained as above
with alkaline sulphides, a complete decomposition is obtained with the pro-
duction of the hydrates of soda or potash, and of the sulphide of copper,
which precipitate after being separated, washed, and dried, will regain its
desulphurising properties by being wasted or calcined. These improvements
further consist in the employment, not only of the oxides of the several metals
which are capable of combining with and of abstracting the sulphur from
alkaline sulphides in solutions, but in the employment of carbonates of the
metallic oxides, and I find that the desulphurising of solutions as herein-
mentioned may be effected sometimes more advantageously when the said
decomposition is effected in closed vessels under pressures, and at an elevated
temperature. The solution of caustic soda or of carbonate of soda resulting
from the before-mentioned operations may be concentrated or may at once be
employed in the arts. The process which has been found to answer the best
for the preparation of metallic oxides to be used in the decomposition of
alkaline sulphides consists in mixing one equivalent of nitrate of soda or of
potash with one equivalent of the metallic sulphide, then to heat the mixture

page_text: so as to effect a double decomposition, the final result of which is, first, one
equivalent of soluble sulphate of potash or soda; and second, one equivalent
of insoluble metallic oxide, and nitrous products, which are utilized by passing
them through leaden chambers, where they serve for the preparation of
sulphuric acid, as herein-before mentioned. These improvements, which have
reference to the production of soda and of carbonate of soda from sulphate
of soda, are also applicable to the production of caustic potash and of
carbonate of potash from the sulphate of potash. It is simply requisite to
replace the sulphate of soda by sulphate of potash, but in lieu of using
thirty-five per cent. of. charcoal, about twenty-eight per cent. only should be
employed.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried
into effect, I would observe in conclusion that what I consider to be novel
and original, and therefore claim as the Invention secured to me by the
hercin-before in part recited Letters Patent is,
First, the production of caustic soda and of caustic potash, or of carbonate
of soda and carbonate of potash from sulphate of soda, or from sulphate
of potash or from the sulphides of sodium or potassium, by the processes
.herein-before described.
Second, the mode of preparing the oxide of copper in a state of division
for decomposing the herein-before mentioned alkaline sulphides when in
solution, whereby economy is obtained by utilizing the nitrous acid of the
decomposition of nitrate of soda and sulphide of copper, which is employed
for the manufacture of sulphuric acid.
In witness whereof, J, the said John Henry Johnson, have hereunto
set my hand and seal, the Sixth day of November One thousand
eight hundred and sixty-two.
J. HENRY JOHNSON. (L.S.)