IMPROVEMENTS IN THE MANUFACTURE OF SODA AND POTASH
Year: 1874

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF SODA AND POTASH."-A com-
munication from abroad by Hermann Grüneberg and Julius Vorster,
both of Kalk, in the Empire of Germany.
Sealed the 2nd October 1874, and dated the 28th July 1874.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition,
on the 28th July 1874.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF SODA AND POTASE,"
a communication to me from abroad by Hermann Grüneberg and Julius
Vorster, both of Kalk, in the Empire of Germany, to be as follows :—
This Invention relates to the manufacture of soda and potash, and
consists in causing superheated steam to pass over a mixture of common
salt and alumina, or hydrated alumina if soda is to be produced, and

page_text: over a mixture of chloride of potassium and alumina or hydrated alumina
if potash is to be produced, the same being maintained at a high
temperature. The mixture of the salt and alumina is made into a paste
with water, dried, and the mass broken into small pieces. These pieces
are placed in a retort or cylinder made either of clay or iron, or of iron
lined inside and outside with bricks, and the steam previously heated to
a suitable temperaturo, usually to about a red heat in any well known
form of apparatus, is passed through the heated mass, hydrochloric acid
is evolved, and aluminate of soda or potash, as the case may be, is pro-
duced, which are treated as herein-after described. A series of cylinders,
or retorts, or muffles are used, capable of being hoated externally, and
so arranged as that the steam shall pass into the cylinder which contains
the mixture which has been first acted upon and which is nearly decom-
posed, and then pass from thence into the cylinders or retorts containing
the mass of alumina and salt or chlorido of potassium as the case may
be, which is in a less advanced stage of decomposition. When the
reaction is completed, that is, when no more hydrochloric acid is evolved,
the mass is withdrawn, lexiviated with water, and according as it is
desired to obtain either the carbonate or the hydrate of the alkali the
aluminate is decomposed with carbonic acid or with lime, and the
carbonate or caustic soda or potash resulting may be obtained by any of
the well known processes.
'
Instead of employing alumina for the before mentioned purposes the
oxides of iron or other metallic oxides, or mixtures of the same aro
employed, and as substitutes for the before mentioned substances or in
conjunction therewith either silica or silicates of the alkaline earths, or
mixtures of the same, are employed. The result obtained by the employ-
ment of the substances or compounds, either as substitutes for or in
conjunction with alumina, is treated in a similar manner, and after
lexiviation the caustic or carbonate of soda or potash may be obtained by a
any of the ordinary processes.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said John Henry Johnson in the Great Seal Paten
Office on the 4th January 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, Gentleman, send grecting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, hearing date the Twenty-eighth day of July, in the year
of our Lord One thousand eight hundred and seventy-four, in the
38th year of Her reign, did, for Herself, Her 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, admi-
nistrators, 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 POTASH," a communica-
tion to me from abroad by Hermann Grüneberg and Julius Vorster,
both of Kalk, in the Empire of Germany, upon the condition (amongst
others) that I, the said John Henry Johnson, my executors or admini-.
strators, by an instrument in writing under my hand and scal, should
particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause tho
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, that is to say :—
It is well known that upon passing steam over a mixture of chloride
of sodium or chloride of potassium together with alumina or silica, the
same being heated previously to a high temperature, that the above-

page_text: mentioned chlorides are decomposed, aluminate or silicate of soda or
potash are formed, and hydrochloric acid is evolved. This action
however is very slow, and the requisite temperature must be very high,
and up to the present time no suitable and sufficiently durable material
for the construction of the vessels in which the decomposition was to be
effected has been discovered. Moreover the losses of chlorido of sodium
or chloride of potassium by volatilization at the high temperatures
necessary were very considerable, consequently the above mentioned
reaction never succeeded practically on a large scale. To overcome
these difficulties we have introduced the following improvements :—
-We
'take hydrate of alumina, now manufactured and known as a commercial
product, instead of ordinary or natural alumina. This commercial
hydrate of alumina forms the finest possible powder when dried, and it
is most readily mixed with the chloride of sodium or the chlorido of
potassium, for the purposes herein mentioned.
In carrying out this Invention we prefer to take about two parts by
weight of commercial hydrate of alumina, containing about forty parts
of water and about one part by weight of either of the chlorides before
mentioned, but we do not limit ourselves to these proportions, as we
have found other proportions to produce the desired result. We mako
the mixture into a paste with water, and grind the same in the wet
state in order to obtain as thorough a mixture as possible. For mixing
it thoroughly wo sometimes use a pug mill, or a clay mixing machine,
or other similar arrangement. The mass thus obtained is then dried
and broken into small pieces. It is necessary to dry the mass very
quickly and at a high temperature, so that the respective constituents
of the mixture are not separated. The dried pieces thus obtained wo
place in a retort or cylinder, made either of clay, or of cast iron, or of
iron lined inside or outside, or both, with fire-brick or fire-clay. We do
not limit ourselves to any special form of apparatus or material for the
decomposing vessels, as retorts, pipes, crucibles, or muffles can he
successfully employed. We then heat the decomposing vessels charged
with the above described mass to a suitable temperature, preferably a red
heat, which need not exceed about 800 centigrade. We generally employ
a temperature of between 700° and 800° centigrade, and we have found
the decomposition at that temperature is the most regular; a higher
temperature can be employed, but we do not restrict ourselves to tho
above mentioned temperatures.

page_text: The steam to be passed through the mass is previously heated in any
well-known apparatus for superheating steam or gases to a suitable tem-
perature, usually reaching from about 600 to 800 degrees centigrade. The
steam used need not necessarily be of a higher, pressure than is sufficient
to make it pass through the, charge in the decomposing vessel.; Wo
prefer to work with as low a pressure as possible, in order to obtain
strong hydrochloric acid, and to be enabled to use small steam super-
heaters for large decomposing vessels.
fi
BARPED THE
We employ a series of cylinders, or retorts, or muffles for the decom-
posing vessels, standing upright, inclined, or horizontal, and we pass tho
steam from the cylinder or decomposing vessel which contains the mass
most nearly decomposed successively into those cylinders, retorts,
muffles, or decomposing vessels which contain the mass of alumina and
salt or chloride of potassium in a less advanced state of decomposition.
The steam or the steam mixed with hydrochloric acid is introduced at
one end of each respective decomposing vessel, and then passes through
the mass and leaves the vessel at the opposito,cnd: When the reaction
is completo, that is, when no more hydrochloric acid is evolved from one
cylinder or decomposing vessel, wo isolate that cylinder and withdraw
the mass, lixiviato with water, and decompose the aluminate by means
of carbonic acid, as is well understood..
J.
In order to effect the separation of the soda or potash from the alumina
we employ the well known methods used in the manufacture of hydrate
of alumina from kryolite, or from bausite, or diaspore.
La
The hydrate of alumina obtained by precipitation, as before mentioned,
with carbonic acid may again be employed for admixture; with the
chloride of sodium or with the chlorido. of potassium:
j
.. !
The hydrochloric acid evolved in the before-mentioned operation may
be condensed in any well known condensing apparatus.
Instead of employing hydrate of alumina precipitated silica in about
the same proportions-or-mixtures_of_theso two substances may be
employed, and when silica is employed the resulting silicates. may bo
treated in the manner before referred to for effecting the decomposition
of the aluminates, but we prefer the use of hydrate of alumina.
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

page_text: carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therofore claim as the Invention secured
to me by the herein-before in part recited Letters Patent is,-
"
First. The employment of commercial hydrate of alumina in con- ..
junction with superheated steam for effecting the decomposition of 5
chloride of sodium or of chloride of potassium in the manner and for tho
purpose herein-before described.
Second. The employment of precipitated silica in a finely divided
state in conjunction with superheated steam for effecting the decom-
position of chloride of sodium or of chloride of potassium in the manner 1
and for the purposes herein-before described.
Third. The peculiar method of preparing the materials herein referred
to prior to their being employed for the purposes of decomposition, as
herein described.
Fourth. The employment of a series of decomposing vessels or li
apparatus, arranged in the manner hercin described, in order that the
steam and the products of decomposition may pass successively through
two or more of the decomposing apparatus or vessels of the series.
In witness whereof, I, the said John Henry Johnson, havo to
this my Specification set my hand and seal, the Fourth day of 20
January One thousand eight hundred and seventy-five.