IMPROVEMENTS IN THE MANUFACTURE OF CARBONATES OF SODA
Year: 1854

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, and of Glasgow, North Britain, Gentleman,
for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF CARBONATES
OF SODA." A communication.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 8th July 1854.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, and of Glasgow, North Britain, Gentleman, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF
CARBONATES OF SODA" to be as follows, a communication from abroad.
This Invention relates to the application of the gases arising from the com-
bustion of fuel or fuel gases in the manufacture of carbonated compounds of
soda, by double decomposition with corresponding compounds of ammonia, as
is well understood by practical men. The fuel gases and ammonia in any
convenient form are introduced into suitable vessels containing the salt of
soda or its solution which is to be decomposed; the object being, by aid of the
fuel gases, to form a marketable compounds of soda in the presence of or by
the reaction of ammoniacal compounds. An atmosphere of the fuel gases may
also be used during the completion of such process or manufacture. Previous

page_text: to the final escape of the uncombined or unabsorbed fuel gases, they are passed
through or in contact with a solution capable of retaining any ammonia con-
tained in the gases. It is preferred to form these compounds with the fuel
gases under pressure; coke or or anthracite coal is preferred as fuel, the com-
bustion being effected with a strong draft, whilst smoke is to be avoided as
much as possible. The heat arising from the combustion of such fuel may be
economically employed in heating water, burning limestone, or for any other
purpose requiring but a moderate licat, and wherein the fuel gases are not
deteriorated or injuriously contaminated.
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
8th January 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JопN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
and of Glasgow, North Britain, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighth day of July, in the year of our Lord One
thousand eight hundred and fifty-four, in the eighteenth 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, tho 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 there-
after 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 "IMPROVE-
MENTS IN THE MANUFACTURE OF CARBONATE OF SODA," communicated to me
from abroad, upon the condition (amongst others) that I, the said John
Henry Johnson, by an instrument in writing, under my hand and seal,
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.
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 :-

page_text: The said Invention relates, in the first place, to the application of fuel gases
or the active constituents of the gaseous matters arising from the combustion
of fuel, for the prevention of much of the wasteful volatilization of ammonia,
which ordinarily arises during the manufacture of carbonate of soda, accord-
ing to the process described in the Specification of Letters Patent for England
granted to Harrison Gray Dyar and John Hemming, on or about the
Thiertieth day of June, One thousand eight hundred and thirty-eight, for
their Invention of " Improvements in the Manufacture of Carbonate of
Soda." This loss or dissipation of ammonia, which it is the intention of
the present Invention to counteract or obviate, occurs in most, if not in all,
the existing modes of producing carbonates of soda on the same or similar
principles. Secondly, the Invention relates to the application of well-known
means to the purpose of saving, retaining, absorbing, or condensing most or
all of the ammonia which is volatilized during the known modes of manu-
facturing carbonates of soda, before referred to, or during the process, herein-
after described. The principle or essential fact on which the first portion of
the said Invention is based is, the circumstance that ammonia is but slightly
volatile in an atmosphere of puro moist carbonic acid gas at the ordinary
atmospheric pressure and temperature; hence, a current of such carbonic
acid gas may be passed over or through a solution containing both ammonia
and common salt, in equivalent proportions, with a comparitively small loss of
ammonia from such solution by volatilization. Two modes or general systems
are employed for the obtainment of such an atmosphere of carbonic acid gas
from the gaseous products arising from the combustion of fuel or "fuel gases."
The first of these modes involves the purification of carbonic acid gas from
mixture or contamination with the raw fuel gases, so as to obtain carbonic
acid in a state as pure as possible. This purification is effected in two
ways; one is, the forming of highly carbonated compounds of soda and potash,
by the application of fuel gases under pressure, as herein-after described, to
such bodies or to their lower carbonates, or to solutions of any of them, and
then decomposing such highly carbonated compounds or their solutions by the
agency of heat, when carbonic acid gas in a nearly pure condition, but mixed
with more or less steam, is driven off'; the steam being condensed and is sepa-
rated as water, when the gases are cooled, leaving them saturated with moisture,
but not carrying water mechanically. Or, according to the other way, ad-
vantage is taken of the property possessed by water, of absorbing carbonic
acid
gas in greater amount or proportion than oxygen or nitrogen, in applying
fuel gases to water under pressure, as herein-after described, and afterwards
evolving carbonic acid gas from the water by any of the well-known practical

page_text: means, or such as are herein described. The comparitively pure carbonic acid
gas thus obtained may be still further purified by being again absorbed by and
evolved from water.
It is already known that such highly carbonated compounds of soda and
potash and solutions thereof have heretofore been formed by the direct appli-
cation of fuel gases thereto; but this present Invention distinctively consists
in the application of fuel gases under pressure, as herein-after described, to
form these compounds, in order to prepare therefrom carbonic acid gas for the
purposes of the decomposition of salts of soda in the presence or by the reaction
of ammoniacal compounds. It is preferred to employ solutions of carbonate of
potash or carbonate of soda, taking such precautions as to the the strength and
temperature of such solutions as must necessarily be obvious to the practical
man, and the passing such solutions and the fuel gases under pressure in con-
trary directions through columnar structures or towers filled with small pieces
of coke or stone, as is well understood by the practical manufacturer, such
towers being constructed of wrought, or otherwise strong enough to resist
the pressure involved, and provided with the necessary valvular passages for
the entrance and oxit of the gases and solutions. Closed vessels fitted up with
internal agitators or with alternated shelves, to procure a long traverse for the
gaseous matter, and to present a large absorbing surface of the solutions or
other mechanical equivalents, may be employed; but the permeable towers,
to which reference has herein-before been made, are preferred. If the highly
carbonated compounds are formed in a solid state from fuel gases under pres-
sure, they are produced, as is usual, from the damp or crystalline bodies, proper
means being adopted for enabling the carbonating chambers or vessels to resist
the pressure. The peculiar advantage derived from the application of fuel
gases under pressure to form these compounds consists in the ascertained fact
that the process is by this means greatly accelerated. As these compounds
are not perceptibly volatile, the same precautions as herein described are neces-
sary to be observed; when fuel gases are applied to ammonia in solution, are
not nearly so essential, but it is preferred to adhere as closely to these precau-
tionary measures as is possible; and it must be borne in mind, that other rela-
tions remaining the same, the greater the pressure is, the quicker will be the
action of the process. The highly carbonated alkalis so obtained in either the
soluble or solid condition are heated in the usual manner, and the compara-
tively pure carbonic acid gas obtained according to any part of this Invention
is cooled, collected, & employed in the manufacture of carbonates of soda,
according to the principle developed in the Specification of Messiurs Dyer and
Hemming's Patent, herein-before referred to, or according to processes of an

page_text: analogous class; or, as is preferred, such carbonic acid gas is employed in the
said processes under a pressure equal to two or three atmospheres. When
nearly pure carbonic acid gas is obtained from fuel gases by reason of the pro-
perty possessed by water, as hercin-before referred to, the apparatus and general
precautions as herein-before described are employed; but in this case it is
considered to be more essentially necessary to maintain great pressures and
low temperatures, as the greater the pressure the more satisfactory is the
result; and it is not intended at any time to employ a less pressure than is
required so to compress the fuel gases as to obtain as much carbonic acid gas
within the measurement of one cubic foot of such compressed matter as is con-
tained within the measurement of two cubic feet of pure carbonic acid gas at the
ordinary pressure and temperature of the atmosphere. As an example:-Take
the gases arising from the combustion of coke and from the limestone of a
coke limekiln, as in the manner frequently pursued by manufacturers of soda
ash in their "carbonating process," and which manner is preferred for the ob-
tainment of the fuel gases, the limo being afterwards serviceable in the process,
and the carbonic acid gas evolved by the linestone is also useful in adding to
the richness of the fuel gases; and suppose that in such gaseous matter there
is one-fourth of carbonic acid gas, so that at the ordinary atmospheric pressure
and temperature eight cubic feet of fuel gases contain two cubic feet of pure
carbonic acid gas at such pressure and temperature, it is preferred to com-
press such fuel gases to such an extent as will at least reduce them to one-
eighth of their original bulk, thus compressing the eight cubic feet within the
limits of one cubic foot; and as the original eight cubic feet contained two
cubic feet of pure carbonic acid gas at the ordinary atmospheric pressure and
temperature, the cubic foot of gases so compressed inust necessarily contain
the two cubic feet of carbonic acid gas compressed within the limits of one
cubic foot.
For the sake of convenience, and for the purpose of ensuring a better
comprehension of the principle involved in a portion of this Invention, a
cubic foot or other unit volume of gas will be herein-after called one atmo-
sphere, as being about equivalent to one atmosphere of carbonic acid gas,
whether such cubic foot or other unit volume consists of pure carbonic acid
gas at the ordinary atmospheric pressure and temperature, or whether it
consists of fuel gas so compressed, and of the same temperature) as to contain
within the limits of one cubic foot or unit volume of such compressed gases
as much carbonic acid gas as is contained within the limits of one cubic foot
or other unit volunie of pure carbonic acid gas at the ordinary atmospheric
pressure and temperature. And also, when two cubic feet or unit volumes of

page_text: such pure carbonic acid gas, or their equivalent, as herein-before stated, are
compressed within the limits of a single cubic foot, it will be herein-after
termed two atmospheres of carbonic acid gas, and so on, for any higher amount.
Hence, in the herein-before given example of eight cubic feet of fuel gases,
containing at the ordinary atmospheric pressure and temperature two cubic
feet of carbonic acid gas, this measure will represent, according to the herein-
chosen nomenclature, one-fourth of an atmosphere of carbonic acid gas, for
the reason that the gas is expanded or diffused into a space equal to four times.
its normal bulk, and thus is obtained about an equivalent to pure carbonic
acid gas under the pressure of one-fourth of an atmosphere; and when such
fuel gases are compressed, as herein-before instanced, into one-eighth of their
volume, this measure is herein called two atmospheres of carbonic acid, and
about equivalent to pure carbonic acid gas under a pressure of two atmo-
spheres. The water and fuel gases being brought together under pressure, as.
herein-before described, the water absorbs principally carbonic acid gas, a
portion of which is evolved from the water in nearly a pure condition by
effervescence when the water is withdrawn, provided the pressure has been.
great enough to produce at least about two or more atmospheres of carbonic
acid. Heat and mechanical agitation may be applied, if convenient, to effect
the withdrawal of more. or the whole of the gas; and the heated water and
solutions herein-before described may be conveniently cooled before being
again used, by passing them down or through towers, as herein-before men-
tioned, a current of air being made to pass through such towers in a direction
opposite to that of the matters being cooled, so as to cool them by evapora-
tion. It is found to be advantageous to add a small quantity of an alkaline
carbonate to water so employed, to neutralise the corrosive action of the
carbonic acid upon the metallic parts of the apparatus. The carbonic acid
gas procured in this manner is collected and applied as herein-before described.
These two modes of obtaining nearly pure carbonic acid gas from fuel gases
have been described herein, because they undoubtedly involve distinct prin-
ciples of action; but they may be combined to work together, and a solution
of an alkali may thereby have an alkali carbonated to the highest point, and
the water of the solution may at the same time be highly impregnated with car-
bonic acid; and other relations remaining the same on heating such solutions;
as herein-before described, the greatest obtainable quantity of nearly pure car-
bonic acid gas may be produced from a given quantity of liquid. Both modes
give good results, but it is believed that the process with water only is of the
greater practical value, inasmuch as it does not involve the use of the valuable
solutions, nor necessarily the heating and cooling of large quantities of liquids.

page_text: In using fuel gases for carrying out any part of this Invention, from what-
ever source such fuel gases may be derived, they must necessarily be cooled,
moistened, and freed from the presence of sulphurous acid gas and from
sulphuretted bydrogen. The heat of combustion may be economically applied
by using it for heating boilers or pans, or other vessels containing water or
other solid or liquid bodies; but care must be taken, first, to make as much
carbonic acid gas as is possible; secondly, to avoid the production of smoke,
and, lastly, to prevent the leakage of air into the flues, as well as avoiding all
other causes leading to deterioration or attenuation. Effective refrigeratory
means must obviously be used, and it is desirable to have a tower filled with
pieces of limestone kept constantly moist with water, as, in passing through
such a permeable medium, the fuel gases are moistened and purified from
sulphurous acid and other contaminating gases. Where gases and liquids are
used under pressure, it is preferred to employ these matters as they escape in
furnishing auxiliary sources of power, the compressed air being employed
expansively in suitable motive-power engines. Similarly, the liquids are to be
used in hydraulic engines, and the power thus actually used is little more than
is due to the friction of the working parts. Any of the well-known means may
be employed in compressing the gases, but a set of pumps working in concert
is preferred, the gases being received into the first pump of the series, and
thence forced into the second, and so on, throughout the series, the capacities
of the pump cylinders being in inerse ratios to the pressures. For example,
in compressing gaseous matter to twenty-seven atmospheres, three pumps are
employed, their capacities being as twenty-seven, nine, and three, the gases
being first taken into the pump twenty-seven, and finally expelled from the
pump three. These compressing pumps are placed in a cold water bath,
which also contains the auxiliary compressed air and hydraulic cylinders, so
that the heat given out to the water from the compressing pump cylinders is
necessarily absorbed by the same gases on their expansion. Advantage is
taken of the cooling power of gascous expansion to cool the gases used under
pressure in the process of decomposing the soda salt, passing the gases through
a lightly loaded valve, or its mechanical equivalent, so that the gases in the
decomposing chamber or vessel are under slightly less pressure than in the
pumps, and the heat arising from the chemical combination is thus absorbed.
It is to be understood that the carbonic acid gas purified from fuel gases,
as herein-before described, is intended to be employed in the place of the
carbonic acid employed by Dyar and Hemming and others for all purposes to
which carbonic acid gas is applicable, and as the process described by Dyar
and Hemming and others, whereby a salt of soda, generally common salt, is

page_text: decomposed by or in the presence of ammonical carbonates; for the production
of carbonates of soda admits of many variations as to the time or mode of
applying carbonic acid gas, particularly as to whether the ammonical carbonates
are partly or wholly formed first and then added to the soda salt, or whether
they are formed in the solution of or upon the soda salt. The essential point
aimed at, as is well known, consists in the using the ammonia over and over
again with the least possible loss; and the solutions obtained from the
precipitates of the carbonates of soda, and the solutions arising from the
ordinary arrangements for catching or condensing the volatilized ammonia,
or from the means herein-after described, are the principal vehicles or means
whereby the circulation of the ammonia is effected. These solutions contain
sal animoniac, the excess of ammonical carbonates, or of the soda salt un-
decomposed; accordingly as either of these matters has been originally in excess,
and an alkaline carbonate, most probably sesqui-carbonate or bi-carbonate
of soda, or a mixture of both. The sal ammoniac or the common salt may be
separated and removed as is well understood, but, generally speaking, it is not
worth while to do this, the solutions being at once heated in closed stills until
they become nearly neutral, collecting the carbonic acid gas and carbonate of
ammonia distilled over. An excess of slaked caustic lime is then added to
the solution, and to insure success in the process, the drying of the ammonical
compounds must be avoided, water being added for the purpose, if required,
as a portion of the ammonia is apparently decomposed or lost for all practical
purposes when evolved from dry mixtures of ammonical salts and caustic, or
carbonated earths or alkalis, heated on the great scale. The whole of the
products of distillation are conducted together through suitable refrigerating
and condensing apparatus, and during their passage through this apparatus,
and by preference, before the ammonical gas and other matters are much
cooled, there is added to them pure or nearly pure carbonic acid gas, at the
ordinary atmospheric pressure and temperature obtained by the process of
Dyar and Hemming and others, or as herein-before described; and the
quantity of vapours, gases, and water are so proportioned as to give, after dis-
tillation and condensation, a liquid containing ammonia and as much carbonic
acid as it can bear without producing a precipitate of any carbonate of soda,
when common salt is dissolved in it to saturation in closed vessels, as well as
to have the ammonia present in such liquid, in such quantity, that when
saturated with common salt the ammonia and the common salt may be in
about equivalent proportions, the ammonia being, by preference, somewhat in
excess. By thus dissolving common salt, any earthy or metallic precipitates
therefrom may be separated by filtration or subsidence, and the heat of the

page_text: combination of so much of the carbonic acid as is contained therein, as well as
that arising from the union of the ammonia with water, is absorbed during the
refrigerating and distilling process and by the act of solution, and less heat is
evolved during the subsequent processes. To such solution contained in
what is herein called a decomposing vessel, there is added carbonic acid gas,
purified from fuel gases, as herein-before described; or fuel gases, as herein-
after described, are applied under the respective pressures herein stated, the
application of such gases being continued until the solution refuses to absorb
more. The solution and precipitate are then withdrawn and separated, and the
precipitate is washed or purified from ammonical salts, adding all the solutions
together, but using the wash liquids over again until saturated, or nearly so,
with sal, ammoniac. The precipitate is then dried and heated in suitable kilns,
furnaces, or retorts; exposure to the atmosphere is avoided as much as possible
throughout the whole process as regards both the solutions and the precipitate
until the latter has been well freed from ammonical salts. If the soda
carbonates required are either the sesqui-carbonate or bi-carbonate, or a
mixture of both, and the precipitate loes not contain sufficient carbonic acid,
this last may be added by the means herein first mentioned for obtaining
bighly carbonated compounds of potash and soda, or other of the well-known
means of forming sesqui-carbonates or bi-carbonates by carbonic acid gas, or
the fuel gases may be used. The solutions are then distilled as herein-before
described, and during such distillation the animonia necessary to supply the
gradual loss is added in any convenient manner. Fuel gases moistened;
cooled, and freed from sulphurous acid, as herein-before referred to, are also
employed, instead of the pure or nearly pure carbonic acid gas, in the vessel
in which the soda salt is decomposed. This is effected by passing through the
decomposing vessel a current of the fuel gases, compressed sufficiently to form
the two atmospheres of carbonic acid gas, as herein-before described, taking care
to maintain the proportion of carbonic acid gas in the gases passing away from
the decomposing vessels (which gases may be employed as auxiliary sources of
power) at not materially less than one atmosphere of carbonic acid gas;-
otherwise ammonia will be volatilised in proportion to the tenuity of the
atmosphere of carbonic acid. The proportion of the compressed fuel gases to
the quantity and surface of the solution, or the proportion to the absorption of
carbonic acid, is so proportioned from time to time, either by passing more
or less compressed fuel gases, or.by injecting more or less of the solution, as to
maintain the proportion of carbonic acid gas in the compressed fuel gases
passing out at nearly one atmosphere of carbonic acid gas. Fuel gases have
already been used under very moderate pressures only, and hence with a great

page_text: amount of volatilization of ammonia in the attenuated atmosphere of carbonic
acid gas. But the essential feature of this portion of the present improvement
consists in maintaining at ordinary temperature such a pressure as shall
insure at least as much carbonic acid gas in a given volume of the super-
incumbent gases as is contained in the same volume of pure carbonic acid
gas at ordinary atmospheric pressure and temperatures. But this mode of
applying fuel gases is not considered so safe, and certain of preventing
practically the volatilization of ammonia as the modes previously described for
obtaining pure or comparatively pure carbonic acid gas from fuel gases, and
employing the carbonic acid gas thus obtained, as herein-before described.
The last part of the present Invention relates to the use of permeable
columns or towers as used by alkali makers as "condensers for muriatic acid,
for the purpose of condensing or absorbing the ammonia which may be
volatilized in the process of decomposing salts of soda, generally common salt,
in the presence or by the reaction of ammonical compounds, as described
in Dyar aud Hemming's Specification, herein-before referred to, as well as by
other parties. Before the final escape of any of the gases used in the process,
and, by preference, after they have been employed as auxiliary sources of
power, and have expanded to atmospheric pressure, they are passed through
one or more such "condensers," moistened with water or with muriatic or
sulphuric acid, the last of a series of such "condensers" being preferred to be
moistened with an acid, whether the others of the series are so moistened
or not.
The solutions obtained from these condensers are distilled to furnish
ammonia, as herein-before described; and in order to avoid the loss of
ammonia, all solutions and precipitates containing ammonia, or any compounds
thereof, when not exposed to pressure, are kept in closed vessels, the upper
portions of which are connected with the permeable towers, a suitable draught
being maintained in the towers. Hence the draught of these "condensers"
will tend to draw air in at any crevice which may accidentally exist in the
closed vessels, and will aid in preventing the escape of any ammonia thereat.
No acriform matter which has been in contact with any solution or body
giving off ammonia or its compounds is allowed finally to escape without being
passed through such permeable towers or "condensers." The employment of
these towers has before been proposed for the previous preparation of car-
bonates of ammonia for the decomposition of soda salts, as berein-before
referred to; and the novelty of this portion of the present Invention consists
in the application of such means of condensation or absorption to the gases
evolved from such decomposition or from its results.

page_text: 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 may observe, in conclusion, that I do not confine or restrict
myself to the precise details or arrangements which I have had occasion to
describe or refer to, as many variations may be made therefrom without
deviating from the principles or main features of the said Invention; but what
I consider to be novel and original, and therefore claim as the Invention
secured to ine by the herein-before in part recited Letters Patent, is,-
First, the application and use of fuel gases, or the gaseous products arising
from the combustion of fuel, for the obtainment of pure or nearly pure car-
bonic acid gas, for the purpose herein-before described, by applying the said
fuel gases under pressure to soda and potash, and to the carbonates or solu-
tions of these matters, so as to form highly carbonated compounds, from which
pure or nearly pure carbonic acid gas is evolved by the agency of heat.
Second, the application and use of fuel gases in procuring comparatively pure
carbonic acid gas, by applying the said fuel gases under pressure to water or to
solutions, so that comparatively pure carbonic acid gas may be obtained when
the water is withdrawn and released from pressure, or when such impregnated
water or solutions are heated.
Third, the application and use of fuel gases under pressure, as herein-before
described, directly to the decomposition of the salts of soda by the reaction of
ammonical compounds, also, as herein-before described, such pressure being
about sufficient for the production of such an atmosphere of carbonic acid gas
as shall prevent any material valatilization of ammonia.
Fourth, the application of "condensers," as herein-before described, for the
absorption or condensation of any ammonia contained in the gases evolved by
the decomposition of the soda salt by ammonical compounds, as herein-before
referred to, as well as for the absorption or condensation of any ammonia con-
tained in the acriform matter evolved from such decomposing process, or from
any products obtained by such process.
In witness whereof, I, the said John Henry Johnson, have hereunto
set my hand and seal, the Eighth day of January, One thousand eight
hundred and fifty-five
J. HENRY JOHNSON. (L.S.)