IMPROVEMENTS IN THE MANUFACTURE OF CARBONATES OF SODA
Year: 1858

page_text: LETTERS PATENT to Jean Jacques Theophile Schloesing, of No. 22, Rue
d'Austerlitz, in the City of Paris, and Eugène Rolland, of No. 21,
Rue de Bellechasse, in the City of Paris, aforesaid, for the Invention
IMPROVEMENTS IN THE MANUFACTURE OF CARBONATES OF SODA."
Sealed the 11th June 1858, and dated the 26th March 1858.
PROVISIONAL SPECIFICATION left by the said Jean Jacques Theophile
Schloesing and Eugène Rolland at the Office of the Commissioners
of Patents, with their Petition, on the 26th March 1858.
We, JEAN JACQUES THEOPHILE SCHLESING, of No. 22, Rue d'Austerlitz,
in the City of Paris, and EUGENE ROLLAND, of No. 21, Rue de
Bellechasse, in the City of Paris aforesaid, do hereby declare the nature
of the Invention for "IMPROVEMENTS IN THE MANUFACTURE OF CARBONATES OF
SODA," to be as follows:-
This Invention has for its object improvements in the manufacture of
carbonates of soda when formed by the decomposition of chloride of
sodium by ammonia and carbonic acid.
In the year 1854 a Patent was granted to one of us for improvements in
the manufacture of carbonates of soda according to this system, and in
the Specification of that Patent the manufacture is described as divided
ol....מ
No text detected.

page_text: into several operations; first, the causing a solution of chloride of sodium
to absorb ammonia and carbonic acid gases, by which a precipitate of
bicarbonate of soda is obtained; second, the filtering out this precipitate
by means of a centrifugal machine; third, the roasting the bicarbonate,
so as to obtain carbonate of soda and carbonic acid, which passes back
to the first or decomposing process; fourth, the separation from the
filtered liquid from the centrifugal machine of carbonic acid, which
passes back to the first or decomposing process; fifth, the separating
from the same liquid the ammonia, which also passes back to the first
process; sixth, the recovery of the chloride of sodium remaining in the
liquid, so that it may be again operated on.
Now, according to our present Invention, these operations, which
previously were only partially continuous, are rendered wholly so, that
is to say, while a given quantity of chloride of sodium is converted into
carbonate of soda, and withdrawn from the converting vessel, a similar
quantity of chloride of sodium is supplied to the vessel, a corresponding
quantity of ammonia is recovered from the filtered liquid and returned
to the vessel, and a corresponding quantity of bicarbonate of soda is
roasted into carbonate, and the carbonic acid returned to the vessel,
as also a further quantity obtained by roasting limestone.
The converting vessel consists of a series of horizontal cylinders to
which a solution of chloride of sodium is supplied at one end, and
circulates through them until it escapes at the other end of the series.
During its passage it arrives first at a point where ammonia is supplied to
it, either in a gaseous form, or, by preference, dissolved in brine; as it
passes on, it next comes in contact with carbonic acid gas supplied from
a limekiln; and, lastly, before its discharge it meets a purer carbonic
acid, obtained partly by roasting the the bicarbonate, and also by
heating the liquid filtered from it. Within the converting vessel are
instruments like paddle wheels carrying a series of floats, which entering
and leaving the liquid in succession keep it in a state of violent agitation.
The gases are drawn through the vessel in a direction opposite to that
of the flow of the liquid by a fan, which also maintains a partial vacuum
in the vessel, and so prevents loss of ammonia by leakage. Before the
gases are allowed to escape into the atmosphere they are caused to pass
through a tower containing coke moistened with water, and this water
is used for dissolving salt. The turbid liquid passing from the con-
verting vessel is filtered by means of centrifugal machines similar to
those used in the manufacture. of sugar, only that they are lined with
close fabric placed over the wire gauze. The machines are completely
cased in to prevent loss of ammonia, and there is a pipe leading from
the case to the coke tower before mentioned; thus a partial vacuum is

page_text: maintained in the case, both by the revolution of the centrifugal machine
itself, and by the sucking action of the fan which draws the gases
through the tower. The liquid to be filtered is fed into the machinė
by a pipe passing into the case through a stuffing box, and in order to
distribute the liquid equally over the filtering surface a a longitudinal
to-and-fro movement is given to this pipe. Before removing the
bicarbonate from the machine it is washed with water run in through
the same pipe; and in order to prevent waste of the bicarbonate the
same washing water may be used several times, but the washing of
every charge should be finished with water which has not before been
used.
In order to convert the bicarbonate of soda into the neutral carbonate
it is passed through a retort of sheet iron, having an axis carrying screw
blades running through it, as is described in the Specification of the
Patent before spoken of as granted to one of us. According to the
present Invention this retort is heated by a fire placed a considerable
distance below it; and this fire is supplied with air by one passage only,
and in this passage is a regulating valve governed by a self-acting
apparatus (of any suitable construction), which opens or closes this valve
according as the temperature in the retort is falling lower or rising
higher than the point to which the thermo-regulating apparatus is set.
The bicarbonate to be roasted is fed into the retort at one end by a
mechanical feeder consisting of a cylindrical chamber having an axis
running through it, on which pallets are fixed, passing from the axis
to the periphery of the cylinder so as to divide it into a series of separate
chambers. The cylinder communicates at its upper part with a hopper
containing the bicarbonate, and at its lower part with the retort, so that
when the axis revolves it conveys measured quantities of bicarbonate
from the hopper to the retort. At the further end of the retort the
now neutral carbonate is discharged into a receiver, from which it is
removed from time to time. This receiver should be clothed with felt
or other nonconducting material, to prevent a condensation of aqueous
vapour taking place within it. The gases and vapours from the retort
pass through a condenser, by which the aqueous vapour and with it the
small quantity of ammonia present are condensed. The liquid from the
condenser is used for dissolving salt at the commencement of the
operation, and the carbonic acid gas passes on into the converting vessel,
as before mentioned, and in its way it passes through a regulator, the
object of which is to prevent the fan which draws the gases through
the converting vessel from producing too much exhaustion in the retort.
and causing an injurious leakage of air. The regulator we use consists
of a small gasometer, to which by counterbalance weights, a slight

page_text: tendency to rise is given; into this gasometer the gas is discharged from
the retort, and from it passes to the converting vessel through an
aperture regulated by the rise and fall of the gasometer, the aperture
being opened wider as the gasometer ascends, and more and more closed
as it descends.
The filtered liquid from the centrifugal machines is run into vats,
where it is allowed to settle until it becomes quite bright; it is then
run into an apparatus for separating the carbonic acid, which it holds
in solution. This apparatus consists of a cylindrical vessel, closed at
the two ends and placed in an upright position; it is divided into three
or other number of separate compartments by transverse partitions,
and the liquid to be treated runs constantly at a regulated speed into
the top compartment in which it rises, until by an overflow pipe it
passes
into the compartment immediately underneath; but to prevent gas or
vapour from passing by this pipe from the top compartment to the lower
one, the end of the pipe is made to dip into the liquid in the lower com-
partment; in a similar way the liquid afterwards passes into the lowest
compartment, and from this it passes into other apparatus to be here-
after described. Through the bottom of the cylindrical vessel a steam
pipe rises up about to the level of the liquid in the lowest compartment,
and a conical vessel is placed over it so that the steam can only escape
by passing under the lower edge of this vessel and bubbling up through
the liquid; the steam with the carbonic acid which it has separated,
passes then from the lowest compartment to the compartment next above
by a pipe passing through the partition which forms the bottom of this
compartment; and this steam pipe is covered in the same way as the
steam pipe in the lowest compartment, so that the steam and gas from
the lowest compartment are caused to bubble through the liquid in
this compartment, producing another separation of gas. Lastly, the
steam and gas from the other compartments bubble through the liquid
in the top compartment, and then the gas, together with so much of
the steam as escapes condensation in the apparatus, pass away by a pipe
leading either directly to the converting vessel or to the gasometer
before mentioned, as in connection with the retort for roasting the
bicarbonate. From the lowest compartment of the apparatus for
separating the carbonic acid the liquid passes to another apparatus,
intended principally to separate the volatilizable ammonia, but which
also separates any free carbonic acid remaining in the liquid. This
apparatus is similar to that already described, with the exception only
that it, by preference, is divided into two compartments, only the
separation of the ammonia is caused by raising the liquid to a higher
temperature to that attained in the first vessel. The ammonia separated

page_text: is either returned directly to the converting vessel, or it is dissolved in
salt water before introducing it to this vessel. This operation is carried
on in an apparatus which will be described hereafter. After the separa-
tion of the volatilizable ammonia, the liquid passes on to another
apparatus, where it is mixed with lime to set free the ammonia which
had been rendered fixed by combination with the hydrochloric acid
from the salt. This apparatus is of a cylindrical form, and contains
a mechanical agitator for completely mixing the contents. The lime to
be mixed with the liquid enters the vessel by a passage from a hopper,
which contains the lime mixed with water to form a paste; and the
quantity of lime introduced and mixed with the liquid is regulated by
the revolutions of a screw contained in the passage which connects the
hopper with the mixing vessel.
The next operation has for its object the separation of the ammonia
set free by, the addition of lime. For this purpose an apparatus is
employed which is similar in principle to those used for separating the
carbonic acid and the first portion of the ammonia, only, in place of con-
taining two or three compartments, it contains, by preference, nine,
and in the centre of each of the partitions dividing these compartments,
and also in the top of the apparatus, there is a manhole to allow of the
deposit produced by the lime being readily removed in place of the
central steam pipe used in the apparatus before described. There are
in each compartment four steam pipes having covering vessels, as before,
ranged round the central manhole. The liquid from the mixer is intro-
duced into this apparatus at the third compartment from the top, and
descends regularly to the bottom compartment, from which it is allowed
to escape. The ammonia and vapour produced pass from the top of the
apparatus to a condenser, and the liquid there separated runs back into
the apparatus into the second compartment from the top; the top com-
partment is left dry to prevent any liquid being mechanically carried
over into the condenser. The ammonia vapour after passing through
the condenser mixes with the ammonia vapour before separated, and
passes into the apparatus in which it is to be dissolved in salt water.
This apparatus also consists of an upright cylinder, divided by transverse
partitions into compartments (by preference 6 or 7) each furnished with
an overflow pipe to allow the liquid to descend from one to another; but
these overflow pipes do not dip into the liquid in the compartment below
as in the other apparatus, for in this case the gas enters the apparatus
with the liquid at the top, and descends with it from stage to stage until
it is ultimately dissolved. The liquid as it passes from one compart-
ment to another falls into funnels, which take it down to the bottom of
the next compartment, so as to prevent it passing directly to the next

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Jean Jacques Theophile Schloesing and Eugène Rolland
in the Great Seal Patent Office on the 25th September 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JEAN
JACQUES THEOPHILE SCHLOESING, of No. 22, Rue d'Austerlitz, in the City
of Paris, and EUGENE ROLLAND, of No. 21, Rue de Bellechasse, in the
City of Paris aforesaid, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of March, in the year of our
Lord One thousand eight hundred and fifty-eight, in the twenty-first
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto us, the said Jean Jacques Theophile Schloesing and Eugène
Rolland, Her special licence that we, the said Jean Jacques Theophile
Schloesing and Eugène Rolland, our executors, administrators, and
assigns, or such others as we, the said Jean Jacques Theophile Schloesing
and Eugène Rolland, our executors, administrators, and assigns, should
at any time agree with, and no others, from time to time and at all times

page_text: 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 CARBONATES OF SODA," upon
the condition (amongst others) that we, the said Jean Jacques Theophile
Schloesing and Eugène Rolland, our executors or administrators, by an
instrument in writing under our or their hands and seals, or under the
hand and seal of one of us or them, 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 we, the said Jean Jacques Theophile Schlesing
and Eugène Rolland, 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 improvements in the manufacture of
carbonates of soda when formed by the decomposition of chloride of
sodium by ammonia and carbonic acid.
In the year 1854 a Patent was granted to one of us for improvements
in the manufacture of carbonates of soda according to this system, and
in the Specification of that Patent the manufacture is described as
divided into several operations; first, the causing a solution of chloride
of sodium to absorb ammonia and carbonic acid gases, by which a pre-
cipitate of bicarbonate of soda is obtained; second, the filtering out the
precipitate by means of a centrifugal machine; third, the roasting the
bicarbonate, so as to obtain carbonate of soda and carbonic acid, which
passes back to the first or decomposing process; fourth, the separation
from the filtered liquid from the centrifugal machine of carbonic acid,
which passes back to the first or decomposing process; fifth, the separa-
ting from the same liquid the ammonia, which also passes back to the
first process; sixth, the recovery of the chloride of sodium remaining in
the liquid, so that it may be again operated on.
Now, according to our present Invention, these operations, which
previously were only partially continuous, are rendered wholly so, that
is to say, while a given quantity of chloride of sodium is converted into
carbonate of soda and withdrawn from the converting vessel a similar
quantity of chloride of sodium is supplied to the vessel, a corresponding
quantity of ammonia is recovered from the filtered liquid and returned
to the vessel, and a corresponding quantity of bicarbonate of soda is

page_text: roasted into carbonate, and the carbonic acid returned to the vessel, as
also a further quantity obtained by roasting limestone.
The converting vessel consists of a series of horizontal cylinders to
which a solution of chloride of sodium is supplied at one end, and
circulates through them until it escapes at the other end of the series.
During its passage it arrives first at a point where ammonia is supplied
to it, either in a gaseous form, or, by preference dissolved in brine; as it
passes on, it next comes in contact with carbonic acid gas supplied from
a lime kiln, and lastly, before its discharge it meets a purer carbonic
acid, obtained partly by roasting the bicarbonate and also by heating
the liquid filtered from it. Within the converting vessel are instruments
like paddle wheels carrying a series of floats, which entering and leaving
the liquid in succession keep it in a state of violent agitation. The gases
are drawn through the vessel in a direction opposite to that of the flow
of the liquid by a fan which also maintains a partial vacuum in the
vessel, and so prevents loss of ammonia by leakage. Before the gases
are allowed to escape into the atmosphere they are caused to pass through
a tower containing coke moistened with water, and this water is used
for dissolving salt.
the same.
A converting vessel constructed according to our Invention is shown
in plan at Figure 1; and Figure 2 is a side view, partly in section, of
a, b, c, and d, are four cylinders placed horizontally, and
each formed of two semi-cylinders of wrought iron connected together
by screw bolts; these four cylinders communicate the one with the other
by passages; the form of the passages between the cylinders a and b,
and the cylinders c and d, is shown by the section Figure 3, taken at the
line 1, 1, Figure 2; and the form of the passages between the cylinders
b and c is shewn by the section, Figure 4 taken at the line 2, 2, Figure 1,
and by the section, Figure 5, taken at the line 3, 3, Figure 1. Through
the cylinders, axes e, e, pass, and they are supported in bearings at e¹, e¹;
those for their inner end being fixed on the flat tops of the passages
between the cylinders a and b, c and d. At their outer ends the axes
e, e, carry toothed wheels e, e, which are driven at a rate of about
40 to 50 revolutions per minute, and the axes e, e, carry instruments
formed like paddle wheels to agitate the liquid within the cylinders;
these instruments are constructed in the following manner:-Near each
end of the axis, a flanged socket f is fixed, as is shown by the enlarged
views, Figures 6 and 7, and a tube g is bolted at its two ends to the
pieces f, f; this tube thus surrounds the axis for the greater part of its
length. h, h, are discs fixed to the tube near the centre of its length;
and i, i, are other discs carried by the pieces f; these discs have fixed to
them the beaters j, j, in the manner clearly shown by the Drawing, the

page_text: beaters j¹, j', placed at the junctions of the metal rings k, k, (which
embrace the beaters) are wider than the other beaters, and come close up.
to the interior surface of the cylinder. It will be seen that there is a space
at the centre of each cylinder where there are no beaters; at this point
a partition is fixed, through which there is a passage of sufficient size
to allow the liquid and gaseous contents of the vessel to pass freely, but,
nevertheless, the partition serves to prevent any liquid or gas admitted
to one compartment being at once mixed with the liquid or gaseous con-
tents of the other; l' are similar partitions at the ends of the cylinders,
and which serve to prevent the liquid being thrown out of the cylinders
at the opening through which the axes pass; m is a pipe by which salt
water is admitted to the converting vessel; the strength of solution which
we prefer to employ is 30 parts by weight of salt to 100 parts of water.
The liquid entering by the pipe m flows gradually through the convert-
ing vessel, being agitated the while by the beaters, and ultimately issues
by the pipe n. During its passage, it comes first in contact with
ammonia admitted by the pipe o (this ammonia is either admitted as
vapour or by preference dissolved in salt water), afterwards it comes
in contact with an impure carbonic acid, from a lime kiln, which enters
the vessel by the pipe p; and, lastly, the liquid meets with purer carbonic
acid produced by roasting the bicarbonate of soda in the after part of
the process, and which is supplied to the converting vessel by the pipe q;
,, are openings through the top of the channels connecting the
cylinders a and b, b and c, c and d, to facilitate the removal of any deposit
of salt which may take place within these passages or within the ends of
the cylinders a, b, c, and d, at which points it will be seen that the
liquid is sheltered from the action of the agitators by the partitions l'.
In conducting the converting operation, we find it advantageous so to
regulate the speed at which the salt and water passes through the con-
verting vessel that, on its escape by the pipe n, the liquid shall still
contain ten parts of common salt to 100 parts of water, the other twenty
parts of salt being converted into bicarbonate of soda by the action of
the ammonia and carbonic acid, and these gases we introduce in quantity
slightly exceeding that which is thcoretically necessary for the conversion
of the quantity of salt, that is to say, for every equivalent of common
salt we introduce something more than one equivalent of ammonia, and
something more than two equivalents of carbonic acid gas.
pipes by which cold water is admitted to the troughs t, t, and these dis-
tribute it in a thin film over the upper surface of the cylinders, and u, u,
are boards by which the water is brought in contact with the under part
of the cylinders after it has been thrown off by the longitudinal ribs;
is a pipe by which the gases which escape absorbtion escape from the
S, $, are

page_text: converting vessel, and they are led away and admitted at the lower end
of a tower of brickwork shown at Figure 8, which should be made about
35 or 45 feet in height, it contains a number of perforated shelves w, on
which broken coke is placed, and at the top of the tower there is a pipe
pierced with holes, and water is admitted by it, which trickles slowly
over the surface of the coke; the tower is closed at the top by a cover
kept tight by a water joint. The gases are sucked through the tower
by the fan y connected with it by the pipe z.
'This fan y is driven at
such a velocity as to maintain a sufficient vacuum in the converting
vessel, and in other apparatus connected with the tower as herein-after
described, so that any leakage which may take place may be of air
entering the apparatus, thus loss of ammonia is in great part avoided.
It will be seen that, with this arrangement of the apparatus, so long as
the quantities of salt water, ammonia, and carbonic acid admitted
remain unchanged the conversion always takes place under similar cir-
cumstances; this is very essential to the success of the process, and
cannot readily be obtained unless the operation be made continuous.
The turbid liquid passing from the converting vessel is filtered by
means of centrifugal machines, similar to those used in the manufacture
of sugar, only that they are lined with close fabric placed over the wire
gauze; the machines are completely cased in to prevent loss of ammonia,
and there is a pipe leading from the case to the coke tower before-
mentioned; thus a partial vacuum is maintained in the case, both by the
revolution of the centrifugal machine itself, and by the sucking action
of the fan which draws the gases through the tower.
The liquid to be filtered is fed into the machine by a pipe passing
into the case through a stuffing box, and in order to distribute the liquid
equally over the filtering surface a longitudinal to-and-fro movement.
is given to this pipe. Before removing the bicarbonate from the
machine it is washed with water run in through the same pipe; and in
order to prevent waste of the bicarbonate the same washing water may
be used several times, but the washing of every charge should be finished
with water which has not before been used.
Figure 9 is a side view, partly in section, of a centrifugal filtering
machine, arranged in the manner above described. Figure 10 is a
horizontal section, and Figure 11 is a plan of the same. Figure 12 is
a vertical section of a part of the drum on a larger scale. The wire
gauze which forms the walls of the drum we prefer to be of tinned iron
and of small mesh; this drum we line with a cylinder of closely woven
woollen fabric, which is fixed by clamping its edges against the top and
bottom of the drum by clamping plates a, a¹; these are made in segments
of a third of the circle each, and are fixed by bolts b, 6'; the bolts b, b',

page_text: are prevented from turning while the nuts are screwed on by enlarge-
ments formed on them, as is shown, which fit into recesses in the top.
and bottom on the drum. The case containing the drum is closed at
the top by the cover c, to prevent escape of ammonia; this cover is secured
to the case by bolts d and d'; through the cover c is an aperture closed
by a lid e, turning on hinges at e', and arranged to close as nearly air-
tight as possible, by interposing a ring of vulcanized india-rubber
between the surfaces, and by securing the lid by screw bolts f. It will
be seen that the bolts d' are placed at a greater distance from the centre
of the drum than the bolts d, so that they may not interfere with the
closing of the lid; lugs are formed on the case to receive them. The
turbid liquid from the converting vessel passes into the covered tank g,
and is raised from thence by the rotatory pump into the small
cistern i, and it passes from this vessel into the drum of the centrifugal
machine by the pipe j, which passes through a stuffing box in the cover,
and is constantly worked up and down by the arm k, actuated in any
suitable manner, thus the incoming liquid is distributed evenly over the
whole surface of the periphery of the drum; the pipe j is connected
with the cistern i by a flexible pipe to admit of the necessary motion,
as is shown. The filtered liquid passes away by the pipe into a small
receiver m which is kept constantly filled with liquid above the mouth
of the pipe, so as to make an air-tight joint, and from the reservoir m
the liquid overflows into the trough n, which conducts it away into
settling reservoirs by which any bicarbonate escaping the filtering
fabric is retained. The passage o communicates with the coke tower.
Figure 8 and the pipe is connected with the passage o, so that when
the centrifugal machine is at work the fan in communication with the
coke tower maintains a slight vacuun in it, but when the drum of the
centrifugal machine is disconnected from the driving gear, the handle
by which this is effected also acts on the valve p and closes it.
opening through the lid e, which is usually closed by a bung, but which
is removed by the workman when he desires to see how much bicarbonate
has accumulated in the drum. When this coating of bicarbonate becomes
so thick as to prevent the filtration proceeding with sufficient rapidity,
the rotatory pump h is stopped, and when liquid no longer flows from
the machine, the cock r is opened to allow water to descend from the
cistern s to wash the bicarbonate and free it from chloride. In con-
ducting the washing operation the smallest quantity of water that will
produce the desired result should be employed, thus it is advisable to
employ fresh water only to complete the washing which is commenced
with water employed to complete the washing of the last charge. After
the washing operation the lid of the centrifugal machine is opened,
q
is an

page_text: .and the bicarbonate is scraped out and put to dry, either in the air or
with the aid of a gentle heat.
In order to convert the bicarbonate of soda into the neutral carbonate,
it is passed through a retort of sheet iron having an axis, carrying screw
blades running through it, as is described in the Specification of the
Patent before spoken of as granted to one of us. According to the
present Invention this retort is heated by a fire placed a considerable
distance below it, and this fire is supplied with air by one passage only,
and in this passage is a regulating valve governed by a self-acting
apparatus (of any suitable construction) which opens or closes this valve
according as the temperature in the retort is falling lower or rising higher
than the point to which the thermo-regulating apparatus is set. The
bicarbonate to be roasted is fed into the retort at one end by a mechanical
feeder, consisting of a cylindrical chamber having an axis running
through it, on which pallets are fixed, passing from the axis to the peri-
phery of the cylinder so as to divide it into a series of separate chambers.
The cylinder communicates at its upper part with a hopper containing
the bicarbonate, and at its lower part with the retort, so that when the
axis revolves it conveys measured quantities of bicarbonate from the
hopper to the retort. At the further end of the retort the now neutral
carbonate is discharged into a receiver, from which it is removed from
time to time; this receiver should be clothed with felt or other non-con-
ducting material to prevent a condensation of aqueous vapour taking
place within it. The gases and vapours from the retort pass through a
condensor by which the aqueous vapour, and with it the small quantity
of ammonia present, are condensed; the liquid from the condensor is
used for dissolving salt at the commencement of the operation, and the
carbonic acid gas passes on into the converting vessel as before-men-
tioned, and in its way it passes through a regulator, the object of which
is to prevent the fan which draws the gases through the converting
vessel from producing too much exhaustion in the retort, and causing
an injurious leakage of air. The regulator we use consists of a small
gasometer, to which by counterbalance weights a slight tendency to
rise is given; into this gasometer, the gas is discharged from the retort,
and from it passes to the converting vessel through an aperture regulated
by the rise and fall of the gasometer, the aperture being opened wider
as the gasometer ascends, and more and more closed as it descends.
Figure 13 is a longitudinal section of the apparatus which we prefer to
employ for roasting the bicarbonate into the simple carbonate; Figure
14 is a transverse section of the same taken at the line A, A, Figure 13;
and Figure 15 is another transverse section taken at the line B, B,
Figure 13. a, a, is a cylinder of wrought-iron plate, which is set in

page_text: In
brickwork as is shown in the Drawing with a furnace under it; b is an
axis entering the cylinder at one end, and having blades c, c, mounted
on it in the manner shown at Figure 16, these blades run in a spiral
direction through the cylinder, and are at intervals rivetted to hoops
d, d. At their other ends the blades c are attached to another short
axis e in the manner shown at Figure 17. As these blades revolve they
pass very closely to the bottom of the cylinder a, and keep the matters
contained in the cylinder in constant agitation, and also cause them to
travel continuously from the front to the back of the cylinder; the
cylinder is made slightly elliptical. so that the blades in revolving do
not come against the tube f, which is contained in the upper part of
the cylinder (the use of this tube f will be herein-after explained). The
dry bicarbonate is placed in the hopper g, which is closed at the bottom
by the pallet wheel h, and this wheel has on its axis and is driven by
the ratchet wheel i, which itself receives motion by a driver having a
to-and-fro motion communicated to it in any convenient manner.
'practice we have found it convenient to feed the bicarbonate into the
cylinder at the rate of about 175 lbs. per hour, and also to cause the
blades c to make 10th to 20th of a revolution per minute; j is a receiver
at the end of the cylinder c, into which the carbonate falls; this vesscl
is of metal, and is clothed with felt to prevent radiation of heat, so that
condensation of the moisture evaporated in the cylinder a may not take
place within the receiver; at the bottom of the receiver is a door which
is opened or removed from time to time to empty the vessel. k, k, are
the fire bars of the furnace, which are, as it will be seen, placed a con-
siderable distance below the cylinder. The ash-pit of the furnace is
closed in front and is made as nearly air-tight as possible; it is only
opened to remove the ashes. Air is admitted to the closed ash-pit by a
passage m, which at its upper end is furnished with a valve n, which
is governed in the following manner:-The tube f within the cylinder a
contains air, it is closed at one end, and its other end communicates by
a small pipe with a closed cup containing mercury; this cup is mounted
on the upper end of one of the legs of a U tube, the other leg of which
also has a cup mounted on it, but this latter cup is open; thus when
the heat expands the air in the tube f it presses on the surface of the
mercury in the closed cup, and causing some of it to pass into the U
tube produces a corresponding rise of the mercury in the open cup; and
a metal float on the surface of the mercury in this cup communicates this
motion to a lever supported on a centre or fulcrum, and having the
valve n connected with its other end. The products of combustion
from the furnace pass away to a chimney by the flue o. The gas and
vapour produced in the cylinder a pass away by the passage p into

page_text: the condensor q, which is surrounded by an outer vessel containing
cold water. The water enters continuously at the bottom of the vessel
by a piper, and overflows at the top by the spout s; the liquid depo-
sited flows into the trough t, and is employed in dissolving salt prepara-
tory to introducing it into the converting vessel; the carbonic acid gas
liberated in the roasting process passes by the pipe u into the regulating
gasometer, Figure 18, and from thence by the pipe w to the converting
vessel, which it enters by the pipe 9, Figure 1; the gasometer vis
suspended from a beam as is shown, and is counterpoised to such an
extent that it has just a tendency to rise to its highest position, but if
the vacuum produced within it by the fan exceeds that which is required,
viz. about th of an inch of water, the gasometer is drawn down to its
lowest position; x is a cone suspended from the top of the gasometer,
and entering the mouth of the pipe was the gasometer rises and falls,
this cone opens and closes to a greater or less extent the mouth of the
pipe w, and thus the vacuum within the roasting cylinder remains
nearly uniform whether the quantity of gas liberated within it be small
or great.
The filtered liquid from the centrifugal machines is run into vats,
where it is allowed to settle until it becomes quite bright, it is then run
into an apparatus for separating the carbonic acid which it holds in
solution. This apparatus consists of a cylindrical vessel closed at the
two ends and placed in an upright position. It is divided into three or
other number of separate compartments by transverse partitions, and
the liquid to be treated runs constantly at a regulated speed into the top
compartment, in which it rises until by an overflow pipe it passes into
the compartment immediately underneath; but to prevent gas or vapour
from passing by this pipe from the top compartment to the lower one,
the end of the pipe is made to dip into the liquid in the lower compart-
ment; in a similar way the liquid afterwards passes into the lowest
compartment, and from this it passes into other apparatus to be here-
after described. Through the bottom of the cylindrical vessel a steam
pipe rises up about to the level of the liquid in the lowest compartment,
and a conical vessel is placed over it, so that the steam can only escape
by passing under the lower edge of this vessel, and bubbling up through
the liquid the steam, with the carbonic acid which it has separated,
passes then from the lowest compartment to the compartment next above
by a pipe passing through the partition which forms the bottom of this
compartment, and this steam pipe is covered in the same way as the
steam pipe in the lowest compartment, so that the steam and gas from
the lowest compartment are caused to bubble through the liquid in this
compartment, producing another separation of gas; lastly, the steam

page_text: and gas from the other compartments bubble through the liquid in the
top compartment, and then the gas, together with so much of the steam
as escapes condensation in the apparatus, pass away by a pipe leading
either directly to the converting vessel or to the gasometer before men--
tioned, as in connection with the retort for roasting the bicarbonate.
Figure 19 shows a longitudinal section of the apparatus which we-
employ to separate the carbonic acid gas from the liquid which flows
from the centrifugal machines. a is a vat containing the liquid which
has been rendered perfectly clear by settling in a reservoir; from this.
vessel it passes by the bent tube b into the upper compartment of the
apparatus, and when this compartment is full it descends to the middle
compartment by the pipe c, and from this, in turn, it descends by the
pipe d into the lowest compartiment from which it escapes, as will be
herein-after described. e'is a pipe by which steam enters the apparatus;
this pipe projects up into the lowest compartment, and is covered by
the conical vessel f, which is closed at the top, and its lower edge is
only a short distance above the bottom of the compartment; thus the
steam entering by the pipe e has no means of escape except by bubbling
up through the liquid in the compartment, in doing which it carries
with it some of the carbonic acid gas. Afterwards the steam and gas
passes up by the pipe g into the compartment above, where it is in a
similar manner caused to pass through the liquid in this compartment.
The liquid in the lowest compartment being kept at or near the boiling.
point, a large proportion of the steam admitted passes into the central
compartment, where the heat is considerably under the boiling point
(being prevented from rising by regulating the quantity of steam
admitted to the apparatus), and in this compartment almost all the
steam which enters it is condensed, and it is principally heated carbonic
acid gas which passes into the upper compartment and forces its way
through the liquid contained in it; by this passage the gas becomes com-
paratively cool (for the temperature of the liquid in the upper compart-
ment is kept at about 100 to 120° Fahrenheit); the gas then passes by
the pipe to the gasometer, Figure 18, or else directly into the con-
verting vessel. From the lowest compartment of the apparatus for
separating the carbonic acid, the liquid passes to another apparatus
intended principally to separate the volatilizable ammonia, but which.
also separates any free carbonic acid remaining in the liquid. This
apparatus is similar to that already described, with the exception only
that it, by preference, is divided into two compartments, only the sepa-
ration of the ammonia is caused by raising the liquid to a higher
temperature to that attained in the first vessel. The ammonia separated
is either returned directly to the converting vessel, or it is dissolved in

page_text: salt water before introducing it to this vessel; this operation is carried
on in an apparatus which will be described hereafter.
Figure 20 is a longitudinal section of the apparatus for separating the
carbonate of ammonia. The liquid escapes from the lowest compart-
ment of the apparatus, Figure 19, by the pipe i, into the upper
compartment of the apparatus, Figure 20, which, except in the number
of compartments employed, resembles the apparatus, Figure 19, already
described. It is preferred that the pipe i should be bent in the direction
shown by dotted lines to prevent inconvenience should irregular con-
densation take place within the apparatus. Steam is admitted at the
bottom of the apparatus by the pipe a, and the steam with the carbonate
of ammonia separated by it escapes by the pipe b. The vapour escap-
ing by the pipe b may be conducted at once to the converting vessel,
but as it is desirable to keep the temperature of this vessel as low as
possible; it is better to condense the vapour previously in salt water;
the manner of effecting this will be herein-after described. After the
separation of the volatilizable ammonia the liquid passes on to another
apparatus, where it is mixed with lime to set free the ammonia which
had been rendered fixed by combination with the hydrochloric acid from
the salt. This apparatus is of a cylindrical form, and contains a
mechanical agitator for completely mixing the contents; the lime to be
mixed with the liquid enters the vessel by a passage from a hopper,
which contains the lime mixed with water to form a paste, and the
quantity of lime introduced and mixed with the liquid is regulated by
revolutions of a screw contained in the passage, which connects the
hopper with the mixing vessel.
Figure 21 is a longitudinal section of the apparatus we employ for
mixing lime with the liquid to set free the ammonia contained in it, as
chloride of ammonium; and Figure 22 is a transverse section of the
same. The liquid enters the cylindrical body of the apparatus by the
bent pipe a; b is an axis passing through this vessel and having a mixer
formed like a paddle wheel mounted on it. This axis should be driven
at about 10 to 15 revolutions per minute. c is a hopper, into which
lime mixed with water so as to form a paste is placed. At the bottom of
the hopper there is a screw d, to which a slow motion is given to cause it
to discharge the lime at a uniform speed into the body of the apparatus.
The screw d should be driven at such a speed as to supply a somewhat
greater quantity of lime than is required to decompose the chloride of
ammonium in the liquid, so as to ensure that none of the chloride shall
escape decomposition. The liquid when thoroughly mixed with lime
passes by the pipe e to other apparatus, and there is on this pipe a
cock by which a small quantity of the liquid may be drawn off from
f

page_text: time to time to be examined to ascertain that the lime is being added
in suitable proportion. The next operation has for its object the
separation of the ammonia, set free by the addition of lime, for this
purpose an apparatus is employed which is similar in principle to those
used for separating the carbonic acid and the first portion of the ammonia,
only, in place of containing two or three compartments, it contains by
preference nine, and in the centre of each of the partitions dividing
these compartments, and also in the top of the apparatus, there is a
manhole to allow of the deposit produced by the lime being readily
removed. In place of the central steam pipe used in the apparatus
before described, there are in each compartment four steam pipes, having
covering vessels as before ranged round the central manhole. The
liquid from the mixer is introduced into this apparatus at the third
compartment from the top, and descends regularly to the bottom com-
partment, from which it is allowed to escape. The ammonia vapour
produced passes from the top of the apparatus to a condenser, and the
liquid there separated runs back into the apparatus, into the second
compartment from the top; the top compartment is left dry to prevent
any liquid being mechanically carried over into the condenser. The
ammonia vapour after passing through the condenser mixes with the
ammonia vapour before separated, and passes into the apparatus, in
which it is to be dissolved in salt water.
Figure 23 is a longitudinal section of a portion of an apparatus
such as we employ for separating the ammonia set free by the addition
of lime. It differs only slightly from the apparatus employed for
separating the carbonic acid and carbonate of ammonia. It is divided
into nine compartments by partitions, and in the centre of each parti-
tion, and at the top of the apparatus is a manhole a, fitted with a
cover b; and these covers can be removed from time to time to clear
away the deposit of lime left by the liquid in passing through the
apparatus. Figure 24 is a transverse section; taken through one of the
compartments, showing the central manhole, with four vapour passages
covered with inverted cones c ranged round it. Figure 25 is a vertical
section, on an enlarged scale, showing the arrangement of one of the
manholes a, with its cover. It will be seen that from the hole through
the partition a vertical ring or tube rises above the level of the liquid in
the compartment, and a larger ring or tube formed on the cover b
descends over the first, and is attached at its lower edge to the partition.
This arrangement renders unnecessary the making of an air-tight joint
round the cover, for if any steam and vapour passes, it can only do so
by bubbling up through the liquid in the compartment. Figure 26 is
a vertical section on an enlarged scale of one of the vapour passages

page_text: with its cone c covering it. The vapour passages are made of a conical
form in this apparatus in place of being cylindrical, as in Figures 19
and 20, because the liquid when mixed with lime is liable to foam; and,
but for this construction of the passages, the foam might be carried with
the vapour into the compartment above. d, d, are pipes connecting
the different compartments, and by which the liquid entering the
apparatus by the pipe leading from the lime mixing apparatus, descends
from one compartment to another until it ultimately escapes by the
pipe e. This pipe is bent downwards a distance of six or seven feet and
then rises again to about the height shewn in the Drawing, an arrange-
ment which avoids inconvenience from absorbtion or condensation.
f, f, are vertical partitions, of which there is one in each compartment,
and the pipe d by which the liquid descends into the compartment is
placed on one side of the partition f, and the pipe d by which the liquid
descends to the compartment below on the other side of the partition f;
thus the liquid is compelled to make a complete circuit of each compart-
.ment. The steam admitted at the bottom of the apparatus passes
upwards, carrying the ammonia vapour with it until it escapes by the
pipe g at the top of the apparatus. The quantity of steam admitted
to the apparatus is such as to keep the liquid in all the compartments
at a boiling temperature. The pipe g leads the steam and vapour of
ammonia into a condenser, of which Figure 27 shows a vertical
section; it consists of two cylinders a and b, one placed within the other,
and both bolted at the top to the casting c which is formed with passages
so as to connect the pipe by which the steam and vapour enters with
the space between the two cylinders; these at their lower ends are
bolted to the cast-iron ring d from which pipes descend connecting the
space between the cylinders with the exit pipe e. f is an external case,
to which cold water is constantly admitted at the bottom, and from
which it escapes at the top. The water formed by the condensation of
the steam in the condenser, and which water is saturated with ammonia
passes by the pipe g into the second compartment of the apparatus,
Figure 23, where the ammonia is again separated. The vapour of
ammonia from the condenser, and which escapes absorption by the
condensed water, passes on by the pipe h to an apparatus in which it is
dissolved in salt water previous to the salt water being admitted to the
converting vessel.
Figure 28 is a longitudinal section of this apparatus, which also
consists of an upright, cylinder divided by transverse partitions into
compartments (by preference 6 or 7), each furnished with an overflow
pipe to allow the liquid to descend from one to another; but these
overflow pipes do not dip into the liquid in the compartment below as

page_text: in the other apparatus, for in this case the gas enters the apparatus
with the liquid at the top, and descends with it from stage to stage
until it is ultimately dissolved. The liquid as it passes from one com-
partment to another falls into funnels which take it down to the bottom
of the next compartment so as to prevent it passing directly to the
next overflow pipe. The whole apparatus is surrounded by a cistern,
through which water constantly circulates to keep it cool. The solution
of ammonia from this apparatus is introduced into the converting vessel,
as before-mentioned to the pipe h by which the ammonia vapour comes
from the condenser; the carbonate of ammonia vapour from the
apparatus, Figure 20, is also admitted, and water in which salt has been
previously dissolved in suitable proportion, as before-mentioned, is led
in by the branch pipe i, and falling into the funnel j passes down to
the bottom of the first compartment of the apparatus while the vapour
passes over the surface of the liquid, the liquid and the vapour together
pass to the second compartment of the apparatus by the pipe k; and
here again, the liquid passes by a funnel to the bottom of the compart-
ment and the gas circulates over the surface of the liquid in the com-
partment; and the same action takes place in every compartment until
the liquid having taken up the ammonia vapour escapes at the bottom
of the apparatus by the pipe l, and it then flows directly to the converting
vessel which it enters by the pipe m, Figure 1. The apparatus,
Figure 28, is surrounded by a cistern through which cold water
constantly passes, entering at the bottom and overflowing at the top, as
is shewn in the Drawing.
In order to generate carbonic acid gas we employ a lime kiln, differing
from an ordinary lime kiln, in that the fuel is burnt on a grate, and the
products of combustion pass up amongst the limestone. The gas from
the furnace passes from the top by a pipe to a washing apparatus, in
which it passes up amongst stones kept constantly moist with water;
the pipe conducting the gas from the washing apparatus leads direct
to the converting vessel, and the fan in connection with this vessel
assists the draught of the lime kiln..
Figure 29 is a longitudinal section of a lime kiln, such as we employ,
and Figure 30 is a transverse section of the same; it consists of a tower
of fire brick a enclosed within a casing of ordinary brick b, and between
the two there is a space c left which is afterwards filled with ashes or
other suitable material; round this tower are ranged three fire grates d,
and they communicate with it by arched openings. e, e, are ash-pits
under the grates, which are closed in front by doors having gratings
in them to admit air. The kiln is closed at the top by an air-tight
cover f, which is only opened when it is necessary to feed the kiln

page_text: with limestone, and then for as short a time as possible. The carbonic
acid gas produced by the combustion of the fuel and the decomposition
of the limestone passes off by the pipe g, and after traversing the
washing apparatus, Figure 31, enters the converting vessel by the pipe p,
Figure 1. The lime is drawn from time to time by the arched openings
h, h, at the bottom of the tower, which at other times are closed by
closely fitting doors, for otherwise the suction of the fan in connection
with the converting vessel would draw an injurious quantity of air into
it. When, the action of the converting vessel is stopped for any reason
the pipe g is closed by a suitable valve, and a valve in the pipe i is
opened, which allows the gas to escape into a chimney.
The washing apparatus, Figure 31, consists of a cylinder a having
within it a grating 6 supporting a number of small stones.
The gas
from the kiln is admitted under the grating and passes up amongst the
stones. c is a perforated pipe, from which a shower of water falls on
to the stones, and after trickling over them escapes at the bottom of
the cylinder by a pipe d. The washed gas passes away by the pipe e,
and is led to the converting vessel. If the manufacture is conducted
in a locality where waste gases consisting principally of carbonic oxide)
from iron or other furnaces can readily be obtained, then the lime
kiln may be heated by consuming within it a mixture of these gases and
common air. The steam required in the different operations is generated
in steam boilers, supplied with the liquid from the ammonia separating
apparatus, Figure 23, (the liquid having been rendered clear by standing
in vats for a sufficient time to allow the complete deposition of the lime.
In the steam boilers it is to some extent concentrated, but when it gets
to the depositing point it is thrown out of the boilers by brine pumps,
or otherwise, and is afterwards further evaporated in open pans, and
the salt which is deposited separated from the mother liquid, as is well
understood in the manufacture of salt. Care is taken not to carry the
evaporation so far as to cause the separation from the liquid of the
chloride of calcium which it contains. The salt obtained is cleansed
by mixing it with a small quantity of water and placing it in a centri-
fugal machine lined with fabric in the manner already described, but
with a fabric less dense in texture, and the liquid separated in this
manner is returned to the evaporating vessel. The solution of chloride
of calcium, after the separation of the salt, is concentrated until its
boiling point rises to about 250° Fahrenheit, and it is then allowed
to crystallize into a solid mass, and in this form it may be sold in the
market.
Figure 32 is a plan showing the manner in which the whole of the
apparatus already described is combined together: in this Figure blue

page_text: lines indicate pipes or passages in which liquid flows, and red lines
indicate pipes or passages through which gases pass. The arrows show
the direction of flow in these pipes.
a, a, a, are vessels for dissolving the salt, and b is a reservoir for
receiving the clear solution which then passes into the converting
vessels c, c, and also in smaller quantity into the ammonia dissolving
apparatus d. The lime kin which supplies carbonic acid gas is shown
at e, and the washing apparatus at f g is the roasting apparatus, and h
is the regulator through which the gas passes to the vessels c, as is
shewn. i is the fan which draws the gases through the apparatus and
maintains the exhaustion necessary to prevent waste of ammonia. j j is
the tower which the gases traverse to reach the fan. is a reservoir
to receive the liquid from the converting vessels, from which it passes
to the centrifugal filtering apparatus l. m, m, m, are settling vats for
the filtered liquid, the last of them contains a small rotatory pump to
raise the liquid into the reservoir n. The pump is arranged to raise
an excess of liquid which flows back by an overflow pipe. The liquid
in the reservoir n is thus maintained at a uniform level, and consequently
the quantity flowing from it into the apparatus o for separating the
carbonic acid is also uniform. p is the apparatus for separating carbonate
of ammonia; q is the lime mixer; is the apparatus for separating the
ammonia set free by the addition of lime; s is the condenser.
In witness whereof we, the said Jean Jacques Theophile Schloesing
and Eugène Rolland, have hereunto set our hands and seals, this
Fifteenth day of September, in the year of our Lord One
thousand eight hundred and fifty-eight.
Witness,
JEAN JACQUES THEOPHILE SCHLESING. (L.S.)
EUGENE ROLLAND.
T. BASSET.
(L.S.)