IMPROVEMENTS IN THE MANUFACTURE OF BICARBONATE OF SODA
Year: 1882

page_text: LETTERS PATENT to Holbrook Gaskell the younger and Ferdinand
."
Hurter Ph: D. both of. Widnes in the County of Lancaster Alkali Manu-
facturers for an invention of "IMPROVEMENTS IN THE MANUFACTURE OF
BICARBONATE OF SODA"
.
PROVISIONAL SPECIFICATION left by the said Holbrook Gaskell the
younger and Ferdinand Horter at the Office of the Commissioners of
Patents on the 17th June 1882.
HOLBROOK GASKELL the younger and FERDINAND HURTER Ph: D. both of
Widnes in the County of Lancaster Alkali Manufacturers "IMPROVEMENTS IN
THE MANUFACTURE OF BICARBONATE OF SODA "
Bicarbonate of soda is usually made by the addition of carbonic acid to
decahydrated carbonate of soda commonly known as "Soda Crystals or by the
addition of carbonic acid to monohydrated carbonate of soda known as "Salts,"
for which latter method Letters Patent were granted to us and to Eustace Carey
on the 16th day of November 1881 No. 5024
Now this Invention relates to the employment of anhydrous carbonate of soda
in and for the production of bicarbonate of soda and our improvements consist in
adding water (preferably in the form of steam) and carbonic acid to such
anhydrous carbonate of soda contained in suitable apparatus until it is converted
into the desired bicarbonate of soda; or the water or the aqueous vapour may be
added first and thus mono-hydrate of soda be formed, which mono-hydrate may
afterwards in the same or in another vessel be converted into bicarbonate of soda
by means of carbonic acid or the water and the carbonic acid may be added
simultaneously to the anhydrous carbonate of soda in order that bicarbonate of
soda may be formed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent_filed
by the said Holbrook Gaskell the younger and Ferdinand Hurter in the Great
Seal Patent Office on the 16th December 1882.
HOLBROOK GASKELL the younger and FERDINAND HURTER Ph.D both of
Widnes in the County of Lancaster Alkali Manufacturers "IMPROVEMENTS IN
THE MANUFACTURE OF BICARBONATE OF SODA
Bicarbonate of soda is usually made by the addition of carbonic acid to
decahydrated carbonate of soda commonly known as soda crystals or by the
addition of carbonic acid to monohydrated carbonate of soda known as "Salts" for
which latter method Letters Patent were granted to us and to Eustace Carey on
the Sixteenth day of November One thousand eight hundred and eighty one,
No 5024.
Now the present Invention relates to the employment of anhydrous carbonate of
soda of sufficient purity in and for the production of bicarbonate of soda and our
improvements consist in adding water (preferably in the form of steam) and 1
carbonic acid to such anhydrous carbonate of soda contained in suitable apparatus
until it is converted into the desired bicarbonate of soda or the water or the aqueous
vapour may be added first and thus monohydrate of soda be formed which mono-
hydrate may afterwards in the same or in another vessel be converted into
bicarbonate of soda by means of carbonic acid, or the water and the carbonic acid 2
may be added simultaneously to the anhydrous carbonate of soda in order that
bicarbonate of soda may be formed.
In carrying out our Invention we find it advantageous to employ an apparatus
such as is illustrated in side elevation end view and plan respectively in Figures 1,
2 and 3 of the accompanying Drawings.
The iron cylinder A is constructed of convenient size (such as for example
8 feet long by 5%, feet in diameter) and is capable of being rotated upon a
horizontal axis. A cylinder of the above mentioned size will hold a charge of
about twenty six hundred weight of the anhydrous carbonate of soda and produces
therefrom about forty hundred weight of the bicarbonate.
The cylinder A is provided with hollow trunnions or axes supported by and
capable of turning in bearings a carried by a suitable framework. The hollow
axis at one end of the cylinder is used for the admission of steam and carbonic acid
gas and that at the other end is used for permitting the exit when desirable of any
superfluous moisture formed therein The hollow axles are continued into the
interior of the cylinder A and deflected upwards as shewn at 6 in Figure 1 for the
purpose of avoiding the lodgment therein of any solid material and the consequent
stoppage of the free passage of the gas into or from the said cylinder. We find it
advisable to have apertures as represented at ee in the cylinder A and exit pipe c
respectively which can be closed air tight in any convenient manner and through
which when necessary the part of the exit pipe c which is inside the cylinder A
may be readily cleansed and freed from dust which is sometimes deposited therein.
Outside the cylinder A the exit pipe c is carried upwards as at c³ to a suitable
height and is then returned downwards and connected by the branch c³ with the
pipe by which the steam and carbonic acid enter at the opposite end of the
cylinder.
2
a
We find that when the pipe c is carried upwards to about 30 feet to meet the
branch that the difference of temperature and consequently the specific gravity
between the gas in the upcast and that in the downcast of the pipe is such that
a circulation of gas can be commenced and maintained when desired through the t
said pipe. In this manner superfluous moisture (if any) is conveyed away from the

page_text: cylinder A and is condensed in the pipes and may be collected and run off through
a lute as shewn at the surplus carbonic acid gas returning to the cylinder by
the branch. Figure shews such an arrangement of lute drawn to a larger
scale. If at any time the aforesaid circulation should not commence when desired
we open for a few moments a tap provided for the purpose at the bottom of the
down cast pipe above the late By so doing the circulation is at once set up in
the pipe c and when commenced continues so long as may be required. Should
at any time the surface of the circulating pipe be insufficient to cool the gas in
order that the moisture may be condensed a portion of the pipe may be more
perfectly cooled by the application of cold water to the exterior of the same.
cylinder A is further provided with openings for inserting and withdrawing the
matter before and after treatment therein respectively, suitable covers being
provided to fit over such openings.
The
Having described one form of apparatus for carrying out our process we will
now proceed to describe the method of working the same which we have found by
practice to give us the best results.
The charge of anhydrous carbonate of soda is introduced into the cylinder A
through the before mentioned openings which are then closed and the cylinder
caused to revolve slowly through the intervention of a pulley and spur gearing G
driven by any suitable motor; we find from practice that from two to six.
revolutions per minute is a sufficient speed. Steam and carbonic acid are then
turned on or admitted into the interior of the cylinder A by the pipe y where
upon the temperature of the carbonate of soda rises and the gaseous mixture is
rapidly absorbed. When absorption decreases the temperature falls. The progress
of the operation or process may be ascertained by withdrawing and testing a
sample from time to time-We find however that with a regular and sufficient
supply of carbonic acid and steam the operation (which lasts from about 10 to 15
hour) is sufficiently uniform that after a short experience sampling and testing
are usually unnecessary. Towards the end of the operation carbonic acid gas only
is admitted and the steam shut off. Any superfluous moisture which may have
been added is withdrawn by means of the circulation pipe above described and in
due time the bicarbonate will be found completely finished and dry and when `
sufficiently cooled ready for immediate grinding and dressing.
Several methods of carrying out our Improvements are however possible and
will under certain circumstances yield more or less satisfactory results.
Such a modified method of procedure may consist in admitting at first steam
only to the anhydrous carbonate of soda, and agitating the charge so long in an
atmosphere of steam until sufficient or rather more water has been absorbed to
convert the soda into a monohydrate of carbonate of soda. This operation is
complete when the charge on testing is found to contain from 49 to 50 per cent
of soda (Na 2 O) The steam is then shut off and carbonic acid gas permitted to
enter the cylinder and the operation then proceeds as directed in the Specification
of No 5024 of One thousand eight hundred and eighty one hereinbefore referred to.
The two operations of steaming and carbonating the anhydrous carbonate may
be carried out in two separate vessels but it will usually be found most convenient
to employ the same cylinder or vessel for both operations.
We find that when operating with charges of from 20 to 30 hundred weight
of anhydrous carbonate of soda it is preferable to add simultaneously steam
and carbonic acid this being another method of carrying out our Improvements.
We prefer however to pass the carbonic acid gas (before it reaches the inlet
pipe pipe y) to the cylinder A through a small tower D or cylinder (about 3 feet
diameter and 4 to 5 feet high) contiguous to the cylinder A and filled with coke
or other suitable material into which tower the requisite steam is passed—The
admission of steam is so regulated that the gas has a temperature about 180°
Fahrenheit when issuing from the said tower This may be ascertained by placing
the bulb of such a graduated thermometer into an aperture provided in the inlet
pipe y as shewn at t-Fig 1. When the carbonic acid gas is saturated with

page_text: steam at this temperature, the gaseous mixture consists nearly of equal parts by
volume of steam and carbonic acid this being the proportion necessary for the
formation of bicarbonate of soda from anhydrous carbonate.
In order to ensure dry bicarbonate we remove any excess of moisture which may
have been absorbed by or condensed upon the charge by means of the circulating
pipe above described and at the same moment at which we begin to circulate as
aforesaid we completely shut off the steam and admit carbonic acid gas only
which is usually effected about 2 or 3 hours before the charge is withdrawn.
If or when dilute carbonic acid is employed such as that resulting from the
combustion of anthracite or coke and where an inert gas or gases are present it is
advisable to have two or more cylinders A connected together and so arranged
that the inert gas or gases may be permitted to escape without undue loss of
carbonic acid. We effect this by having a series of two or more cylinders and
thus pass the oxit gas from one cylinder into the next and so on to the last the
inert gas or gases being allowed to escape freely from the last cylinder of the
Bories. Between each of the cylinders may be provided a gas drying (ie circulating
pipe) and a gas moistening apparatus (ie coke tower) or their equivalents so that
the exit gas or gases from the one cylinder is or are dried or moistened as required
on their way to the next cylinder. The gas pipes can be so arranged as is well
understood that any one cylinder of the series can be isolated for filling or
emptying or for other similar purpose as required.
Figure 5 represents in plan an arrangement of such apparatus as and for the
purposes last mentioned. According to this arrangement three cylinders A', A³, A³,
are employed which are essentially of the same construction as represented by
Figures 1, 2 and 3. Each of them is capable of revolving independently of the
others, suitable gearing G being provided for such purpose. The plan shews one
method of connecting a series of three cylinders so that any one of them may be
isolated and this method can easily be similarly adapted to any number of such
cylinders. The carbonic acid gas from any source enters the distributing
apparatus H by the central pipe y. This distributing apparatus consists of a
cylindrical vessel through the bottom of which pass watertight the central inlet
pipe y, and three pairs of pipes arranged in a circle round this inlet pipe, each pair
being connected with the inlet and outlet of one of the cylinders A', A², A³,
respectively. The cylindrical vessel H contains a sufficient depth of water to
resist any pressure or suction of the gas. The open ends of the pipes reach above
the level of the water a distance at least equal to the depth of the water in the
vessel. Moveable bent pipes are provided to slip over and connect any one of
these pipes with any other. The Drawing represents the whole of the three
cylinders A', A3, A3, connected in the following manner. The central inlet pipe y
is connected to y' by a moveable arm c', so that the carbonic acid may pass to the
moistening apparatus D' and enter into the cylinder A'. The gas passing out by
the pipe c', which is of sufficient length to cool the gas_and_condense excess of
moisture and returns to the distributing apparatus H where the pipe c' is
connected to pipe y³ by a moveable arm c. The gas is thus caused to pass to the
moistening apparatus D2, from this to cylinder A² and returns by pipe of to the
distributor where the said pipe is connected by another moveable arm c' to the
pipe y³. The gas finally passes through the moistening apparatus D³ and cylinder A³,
and returns again to the distributor H by the pipe and thence it may be
allowed to escape by the ring pipes and outlet 2³.
If any water should condense in any of the pipes, it is allowed to escape
through a lute similar to that previously mentioned and represented in Figure 4
of the Drawings. If any of the moistening apparatus is not required for moistening
purposes the steam is not turned on thereto. Figure 6 shews a section of the
distributing apparatus, the Drawing shewing the pipe c³, connected by a moveable
arm to the pipe z forming a ring round the distributing apparatus H, the ring
shaped pipe having four branches ¹¹ and . Three of these branches &¹ are
placed opposite the termini of the pipes c¹ c³ ³, respectively and serve to connect.

page_text: by means of an arm of any of these pipes to the said ring s. The fourth branch &³
of this rings is connected either to a chimney or to an exhauster which removes
the inert gases. All these branches of the pipe s not in actual use are covered by
a lid as at All connections are luted with water as is well understood.
When working in this manner with carbonio acid mixed with inert gases the
amount of steam to be added depends upon the amount of carbonic acid
contained in the gas and must be varied accordingly.
Having now described the nature of our Invention and the means whereby we
carry it into effect we wish it to be observed that we do not confine ourselves to
the particular arrangement form or dimensions of apparatus herein before
described but what we consider to be novel and original and therefore claim
as the Invention secured to us by the hereinbefore in part recited Letters
Patent is:
The production or manufacture of bicarbonate of soda by subjecting anhydrous
carbonate of soda to the action of water or aqueous vapour, and of carbonic acid
gas, substantially as herein before described.
In witness whereof we the said Holbrook Gaskell the younger and
Ferdinand Hurter have to this our Specification set our hands and seals
the fourteenth day of December One thousand eight hundred and eighty
two
HOLBROOK GASKELL, JR. (LS)
FERDINAND HURTER
(L.B.)