IMPROVEMENTS IN THE MANUFACTURE OF BISULPHITE OF Soda
Year: 1882

page_text: LETTERS PATENT to Eustace Carey and Ferdinand Hurter Ph: D. both of
Widnes in the County of Lancaster Alkali Manufacturers for an Invention
of "IMPROVEMENTS IN THE MANUFACTURE OF BISULPHITE OF Soda,"
PROVISIONAL SPECIFICATION left by the said Eustace Carey and Ferdinand
Hurter at the Office of the Commissioners of Patents on the 13th November
1882.
EUSTACE CAREY and FERDINAND HURTER Ph: D. both of Widnes in the County
of Lancaster, Alkali Manufacturers, "IMPROVEMENTS IN THE MANUFACTURE OF
BISULPHITE OF SODA"
Our Invention relates to the manufacture of bisulphite of soda and the employ-
ment of Monohydrated Carbonate of Soda in such manufacture.
In carrying out our Invention we cause gaseous sulphurous acid to be brought
into contact with dry or nearly dry monohydrated Carbonate of Soda contained in
a suitable vessel preferably one in which the material may be agitated-The
Sulphurous acid upon coming into contact with the monohydrated carbonate of
Soda is rapidly absorbed and bisulphite of Soda is produced and Carbonic acid is
evolved which Carbonic acid may be utilized in the manufacture of bicarbonate of
Soda or for any other purpose for which Carbonic Acid is required.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Eustace Carey & Ferdinand Hurter in the Great Seal Patent
Office on the 10th May 1883.
EUSTACE CAREY and FERDINAND HURTER Ph: D. both of Widnes in the County
of Lancaster Alkali Manufacturers "IMPROVEMENTS IN THE MANUFACTURE OF
BISULPHITE OF SODA"
Our Invention relates to the manufacture of bisulphite of soda and the employ-
ment of monohydrated carbonate of Soda in such manufacture.
In carrying our Invention into effect we cause gaseous sulphurous acid to be
-brought-into-contact_with_dry_or_nearly dry monohydrated carbonate of Boda
contained in a suitable vessel preferably one in which the material-may-be
agitated.
:
The sulphurous acid upon coming into contact with the monohydrated carbonate
of soda is rapidly-absorbed and bisulphite of soda is produced and carbonic acid is
evolved which carbonic acid may be utilised in-the-manufacture of bicarbonate of
Boda or for any other purpose-for-which-carbonic.acid is required.
We find that when sulphurous acid is caused to act upon dry monohydrated
carbonate of soda dry bisulphite of soda carbonic acid and heat are-produced.;.
thos, Na, CO, + H₂O + 2 SO, = 2 Na HSO, + CO,. Should the monohydrated
carbonate of soda be slightly damp the amount of heat evolved during the
absorption of sulphurous acid will be sufficient to convert the moisture into vapour
which is carried off by the carbonic acid gas. The bisulphite of soda thus produced
is dry of a degree of purity corresponding to the purity of the monohydrate of
soda employed. When the bisulphite of soda is required pure we employ mono-
hydrated Carbonate of Soda hereinafter termed "Salts" obtained by evaporating by
heat soda solutions previously purified by means of processes described in the
Specifications of Letters Patent granted to us and to Holbrook Gaskell and Henry
Wade Deacon and numbered as follows namely:-N° 2939 in the year of our Lord
One thousand eight hundred and seventy nine; N° 608 in the year of our Lord
One thousand eight hundred and eighty; N° 1161 in the year of our Lord One
thousand eight hundred and eighty one; and N° 5312 in the year of our Lord One
thousand eight hundred and eighty one.
°
The employment of the said salts permits of the manufacture of bisulphite of
soda containing from 58 to 60% of sulphurous acid and of a high degree of purity.
Many kinds of apparatus may be used for the conversion of these salts into
bisulphite of soda In carrying out our Invention, we find it advantageous to
employ an apparatus permitting agitation such as is illustrated in side elevation
end view and plan respectively in figures 1, 2, 3 of the accompanying Drawings.
The iron cylinder A lined inside with lead and of convenient size is capable of
being rotated upon a horizontal axis. The cylinder is lined with lead in order to
avoid the contamination of the salts with iron which would cause them afterwards
to become of an intense yellow colour. The cylinder A is provided with hollow
trunnions or axes supported by and capable of turning in bearings a carried by a
Buitable framework a The hollow trunnion at one end of the cylinder A is used
for admitting sulphurous acid gas and that at the other end is used for permitting
The said hollow
the exit of any superfluous moisture and of the carbonic acid.
trunnions are continued by pipes entering into the interior of the cylinder and

page_text: there deflected upwards as shewn at b for the purpose of avoiding the lodgment
therein of solid material and the consequent stoppage of the free passage of the gas
into or from the cylinder A. We find it advisable to have apertures 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 b of the exit pipe C
which is inside the cylinder Ä may be cleaned easily and freed from dust which is
sometimes deposited there. Having described one form of apparatus we now
proceed to describe the method of working which we find advantageous.
The charge of "salts" is introduced into the Cylinder A which is then closed
and made to revolve slowly by any suitable means such as through the intervention
of a pulley F and spur gearing G driven by any suitable motor. We find from
two to six revolutions per minute are sufficient. Sulphurous acid gases being
turned on or admitted into the interior of the cylinder A by the pipe y the
temperature of the carbonate of soda rises and the sulphurous acid is rapidly
absorbed by the charge. Little carbonic acid is evolved at first but gradually all
the carbonic acid of the carbonate of soda is driven out by the sulphurous acid and
passes away together with any superfluous moisture through the exit pipe C as
indicated by the arrows in Figure 1. The progress of the operation may be ascer-
tained by withdrawing and testing a sample from time to time. When absorption
decreases the temperature falls and the resulting bisulphite will be completely
finished and be found nearly pure containing from 58 to 60 per cent of sulphurous
acid.
Sulphurous acid from any source may be used but we prefer sulphurous acid
prepared from sulphuric acid by acting thereon with coke or charcoal at high
temperatures as is well understood.
Such sulphurous acid is free from atmospheric nitrogen and oxygen but contains
carbonic acid which may be afterwards utilized together with that evolved from
the salts. The absence of oxygen is desirable in order that none of the bisulphite
may become oxidised. The sulphurous acid must be washed and dried. For this
purpose we cause it to pass successively through two small towers U and V made
of or lined with lead and filled with coke. The gas passes in an upward direction
through the tower U meeting there a small stream of water and then passes into the
tower V where it meets a stream of strong sulphuric acid which absorbs the
moisture. The construction of such towers is well understood. The dry sulphurous
acid passes then from the tower V into the Cylinder A. Should at any time the
charge become too dry the moist gas may be caused to pass directly into the
cylinder A from the tower U by means of the pipe W by opening the stopcock X
and closing the stopcock X'.
When using strong sulphurous acid gas as obtained from sulphuric acid and
coke the absorption in the cylinder is so complete that only towards the end of
the operation some sulphurous acid escapes together with the carbonic acid. If it
be desired to utilize the carbonic acid we pass the mixture of the two gases into a
second cylinder similar to the one described and which is charged with fresh salts.
In this cylinder the last traces of sulphurous acid are removed and the carbonic
acid issuing therefrom is sufficiently pure and may be employed for the manufacture
of bicarbonate of soda or for other purposes.
When sulphurous acid is employed which is diluted with atmospheric nitrogen
and oxygen such as sulphurous acid which is obtained by burning brimstone or
pyrites or sulphuretted hydrogen in atmospheric air we employ several cylinders
such as described and so arranged that the gas passes from one to the other in
succession and that any one of the series of cylinders may be isolated or disconnected
from the series for the purpose of charging or discharging its contents as is well
understood.
Having now described and particularly ascertained the nature of our said
Invention and the manner in which the same is or may be used or carried into
effect we would observe in conolusion that what we consider to be novel and original

page_text: and therefore claim as the Invention secured to us by the hereinbefore in part
recited Letters Patent is;-m
The manufacture of bisulphite of soda by the employment and treatment of
monohydrated carbonate of soda by subjecting the same to the action of sulphurous
acid gas substantially as herein before described.
In witness whereof we the said Eustaco Carey and Ferdinand Hurter have
to this our Specification set our hands and seals. this ninth day of May One
thousand eight hundred and eighty three
EUSTACE CAREY
(L.S.)
FERDINAND HURTER (L.S.)