IMPROVE- BETATMO EXT MILD MAXTRACTURE OF ALKALL FROM COMMON SALT
Year: 1853

page_text: LETTERS PATENT to William Gossage, of Widnes, in the County of
Lancaster, Manufacturing Chemist, for the Invention of "IMPROVE-
BETATMO EXT MILD MAXTRACTURE OF ALKALL FROM COMMON SALT."
Scaled the 15th July 185%, and dated the 18th May 1859.
PROVISIONAL SPECIFICATION left by the said William Gossage
at the Office of the Commissioners of Patents, with his Petition,
on the 18th May 1858.
T, WILLIAM GOSSAGE, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF ALKALI FROM
COMMON SALT" to be as follows:-
In manufacturing alkali from common salt by the processes or opera-
tions in ordinary use common salt is firstly decomposed by the action of
sulphuric acid, thus producing sulphate of soda, which product being
mixed with small coal and carbonate of lime, and fluxed in a re-
verberatory furnace, the product then obtained is known by manu-
facturers as rough soda. or black ash. This product being lixiviated
with water yields liquor containing alkali in solution; and for the
purpose of describing my Invention, I will call this liquor "black ash
A

page_text: liquor such liquor being evaporated to dryness, and the product
roasted in a reverberatory furnace, a dry salt is obtained, which is
known in commerce as "soda ash," or "alkali." For the purpose of
manufacturing crystals of soda it is customary to dissolve soda ash in
water, and to concentrate the solution to a suitable strength, when it is
set aside to cool and form crystals. All these operations are conducted
very extensively, and are well understood by alkali manufacturers.
"Black ash liquors" (as these are usually obtained) contain carbonate
of soda, caustic soda, sulphuret of sodiumi, sulphuret of iron (held in
solution by sulphuret of sodium), and ferro-cyanide of sodium. During
the ordinary processes of evaporating "black ash liquors" to dryness,
and roasting the product so obtained, sulphuret of iron and the iron of
the ferro-cyanide of sodium become converted into oxide of iron; and
this substance communicates an objectionable yellow colour to the "soda
ash" produced, rendering it unfit for certain applications. I will now
describe such of my improvements as apply to the separation of sulphuret
of iron from "black ash liquors." I have stated that sulphuret of iron in
such liquors is held in solution by sulphuret of sodium contained therein,
and I have found that if such sulphuret of sodium be converted by
oxydation into hyposulphite or sulphite or sulphate of soda, the sul-
phuret of iron becomes insoluble, and may be separated from the
"black ash liquors" by subsidence or filtration; I effect such oxyda-
tion of sulphuret of sodium contained in "black ash liquors" by
causing such liquors to absorb oxygen from atmospherical air. I
prefer to effect such absorption of oxygen by passing "black ash
liquors through a high tower (which I call an "oxydizing tower",) filled
with small pieces of coke or other suitable material, at the same time
that a current of atmospherical air is caused to pass through the
interstices existing between such picces of coke by connecting the lower
part of the "oxydlizing tower" with a chimney. By this arrangement
an immense number of surfaces moistened with "black ash liquors" is
presented to the current of atmospherical air descending through the
tower, and thereby the absorption of oxygen by such liquors is greatly
facilitated. I provide for the liquors after passing through the oxy-
dizing tower being collected in a pan, to which I apply heat, from

page_text: whence these liquors are pumped up, and caused to flow through such
tower repeatedly, until I find that all the sulphuret of sodium in such
liquors has become oxydized. The sulphuret of iron having, thus
become insoluble, I cause such sulphuret to be separated from the
"black ash liquors," either by subsidence or filtration, and I thus obtain
"black ash liquors" deprived of a considerable portion of the iron pre-
viously contained therein, and which liquors I call "purified black.ash
liquors."
When I propose to use such purified black ash liquors" for the
production of soda crystals I prefer to cause some carbonic acid gas
to pass into the "oxydizing tower" together with this atmospherical, air,
so as to convert caustic soda contained in the "black ash liquors" into
carbonate of soda, & I concentrate the purified black ash liquors
to a strength suitable for the formation of soda by crystalization. I
will herein-after describe the manner in which I prefer to use the
mother liquors" resulting from such crystallization.
When I propose to use such "purified black ash liquors" solely for
the production of "soda ash" I prefer to cause carbonic acid gas to
pass into the "oxydizing tower" together with the current of atmo-
spherical air, so as to convert caustic soda contained in the "black
ash liquors" into carbonate of soda, and I concentrate the " "purified
black ash liquors" (either by the ordinary mode of concentration or
by an improved mode herein-after described) so as to obtain salts
therefrom. I will herein-after describe the manner in which I prefer to
treat such salts previously to using the same for the production of
soda ash."
When I use such purified black ash liquors" for the production of
soda ash, also for obtaining caustic soda in solution, I concentrate the
"purified black ash liquors" (either by the ordinary mode of concen-
tration or by an improved mode herein-after described) so as to obtain
salts therefrom. I will herein-after describe the manner in which I
prefer to treat such salts previously to using the same for the produc
tion of soda ash; also the manner in which I prefer to treat the mother
iquors remaining after the separation of such salts from "purified black
ash-liquors," so as to obtain caustic soda in a marketable form.

page_text: I have herein-before stated that "black ash liquors" contain ferro-
cyanide of sodium, and that the iron of this ferro-cyanide becoming con-
verted into oxide of iron injures the quality of soda ash produced from
such liquors. One of the objects of my Invention is to separate this ferro-
cyanide of sodium from "black ash liquors," and thus to obtain salts
for the production of soda ash free (or nearly free) from such compound
of iron, at the same time that I obtain a valuable article of commerce.
I will now describe the means by which I prefer to effect this part
of my improvements. When I have used purified black ash liquors'
for the production of soda by crystallization, the mother liquors remain-
ing contain nearly all the ferro-cyanide of sodium previously existing in
the "black ash liquors" used. I concentrate such mother liquors, either
by the ordinary methods of concentration, or by my improved mode
hercin-after described, so as to obtain salts therefrom, and I continue
such concentration until nearly all the carbonate of soda previously
contained in the mother liquors used has become deposited as salts. I
withdraw from the concentrating apparatus the salts produced at
different stages of the operation. The first portions of salts deposited
are but little impregnated with ferro-cyanide of sodium, the second
portions of salts contain more of this compound, and the last portions
are strongly impregnated with ferro-cyanide, whilst the mother liquors
still remaining contain a large proportion of this compound in solution.
I separate ferro-cyanide of sodium from such salts by causing the salts
to be washed by water or solution of carbonate of soda filtering through
the same, and for this purpose I prefer to employ a series of four vats
arranged on the same system as the vats which are used by alkali
manufacturers for lixiviating "black ash" on the principle of continuous
lixiviation. I place the salts on perforated false bottoms in these vats
and I introduce water into the vat containing salts least impregnated
with ferro-cyanide, and the solution produced (containing carbonate of
soda and ferro-cyanide) flows from this vat into the adjacent vat
wherein it takes up a further portion of ferro-cyanide, and subsequently
through the two other vats, wherein it becomes still more strongly im-
pregnated with ferro-cyanide. I continue the introduction of water into
the first vat until I find that the salts contained therein have become

page_text: sufficiently deprived of ferro-cyanide to be suitable for the production of
white soda ash, when I discharge such washed salts from this first vat,
and refill it with salts containing much ferro-cyanide, and this vat then
becomes the last of the series. In this mode of washing, the salts
(contained in each vat) successively become those which are least
impregnated with ferro-cyanide, and are subjected to the first action of
water. I mix the solutions obtained by such washing with the mother
liquors remaining from the salting operation by concentration before
referred to and if I find by testing that such liquors contain more
thau ten parts of carbonate of soda for each part of ferro-cyanide of
sodium present therein, I concentrate such liquors so as to obtain a
further quantity of salts therefrom, and I continue such concentration
and separation of salts until I find by testing that the mother liquors
then produced contain less than ten parts of carbonate of soda for each
one part of ferro-cyanide present therein (preferring that the proportion
of carbonate of soda should not exceed five parts for one part of
ferro-cyanide). I prefer to introduce the salts obtained by the last con-
centration above mentioned into the concentrating apparatus in which
"black ash liquors" are being concentrated for the production of salts.
I collect the liquors above referred to as containing less than ten parts of
carbonate of soda for each one part of ferro-cyanide, and I mix these
with sufficient water and caustic lime to convert carbonate of soda
contained therein into caustic soda, and I concentrate the solution thus
obtained until the greater part of the ferro-cyanide becomes separated as
salt, or I. separate such ferro-cyanide by crystalization from the concen-
trated solution; or, in place of converting the carbonate of soda
contained in such liquors into caustic soda, I cause such carbonate of
soda to be converted into bi-carbonate of soda by impregnation with
carbonic acid, and I thus obtain a compound of soda of sparing solubility,
from which I obtain the greater part of the ferro-cyanide by filtration of
water through the same and drainage. I thus obtain a solution of
ferro-cyanide containing a small proportion of soda, and I convert this
carbonate of soda into caustic soda by means of lime. I separate ferro-
cyanide of sodium from such soda, either by salting or by crystaliza-
tion. I refine the ferro-cyanide of sodium (by solution with water and
repeated crystalization) until it is sufficiently pure to be suitable for use.

page_text: I transfer the liquors remaining after the separation of ferro-cyanide
from caustic soda, also the bi-carbonate of soda remaining after the
separation of ferro-cyanide therefrom (when this mode of separation is
adopted), to the concentrating apparatus in which "black ash liquors
are being concentrated for the production of salts.
I have herein-before referred to certain salts obtained from "purified
black ash liquors," when such liquors are used for the production of soda
ash without previously obtaining soda crystals therefrom. The salts so
obtained are impregnated in various degrees with ferro-cyanide of sodium,
according to the stage of concentration at which such salts have been
separated from the liquors. I subject these salts to the same processes
of washing in vats as. I have herein-before described for separating
ferro-cyanide of sodium from similar salts, and when I have thereby
obtained solutions containing a suitable proportion of ferro-cyanide I
subject. such solution to the same processes for separating ferro-cyanide
therefrom as I have herein-before described as suitable for such purpose.
By the means above described I also obtain salts sufficiently deprived
of ferro-cyanide to be suitable for producing white soda ash..
.
I will now describe such of any improvements as apply to obtain-
ing caustic soda in a marketable state, in addition to white soda
ash and ferro-cyanide of sodium, from purified black ash liquors."
When I use such liquors for this part of my Invention I firstly
convert any hyposulphite of soda contained therein into sulphite or
sulphate of soda by oxidation, which I prefer to effect by the
gradual addition of hypochlorite of lime (solution of bleaching powder).
I then concentrate such "black ash liquors" in apparatus of the
ordinary construction used for such purpose, or, by preference, by
my improved mode of concentration (herein-after described), so as
to obtain salts therefrom, and I thus obtain a quantity of salts
impregnated in various degrees with ferro-cyanide of sodium and
caustic soda, and a quantity of mother liquors containing some car-
bonate of soda, much caustic soda, and ferro-cyanide of sodium. I
subject the salts thus obtained to the operation of washing with water
by filtration, herein-before described, so as to obtain salts sufficiently
leprived of ferro-cyanide to be suitable for the production of white sora
ash, and I add the liquors, (containing ferro-cyanide and caustic soda)

page_text: obtained by such washing to the mother liquors which contain caustic
soda. concentrate such mixed liquors, either by means of ordinary
concentrating pans, or, by preference, by the use of my improved mode
of concentration suitable for obtaining caustic soda in a niarketable
state (herein-after described), until the whole or nearly the whole of the
carbonate of soda and ferro-cyanide of sodium previously existing in such
mixed liquors have become deposited as salts, and the solution or
mother liquor remaining contains scarcely any saline matter but caustic
soda. In this state it is suitable for many purposes to which caustic
soda is applicable, and is a marketable product. The salts obtained
by the concentration of such "mixed liquors" above referred to are
impregnated in various degrees with ferro-cyanide of sodium and
caustic soda, and I subject these salts to the operation of washing with
water by filtration herein-before described, so as to separate ferro-
cyanide and caustic soda therefrom; and I prefer to discontinue such
washing before the whole of the ferro-cyanide has been separated from
the salts, and to transfer the washed salts from the vats to a concen
trating apparatus, in which "black ash liquors" are being concentrated
for the production of salts. I examine the liquors obtained by such
washing, and if these liquors are found to contain more than ten parts
of carbonate of soda for each part of ferro-cyanide of sodium contained
therein, I subject such liquors to a further process of concentration, so
as to obtain salts therefrom; but if such liquors contain less than ten
parts of carbonate of soda for each part of ferro-cyanide of sodium
contained therein, I proceed to obtain ferro-cyanide of sodium there-
from by some of the means which I have herein-before described as
suitable for separating such ferro-cyanide from similar liquors.
I have herein-before referred to my improved mode of concen-
trating black ash liquors" (in the manufacture of alkali from common
salt) for the purpose of obtaining salts therefrom suitable for the manu-
facture of soda ash. I will now describe this part of my Invention.
I provide a long iron pan, heated by means of a special fire under-
neath the same, or by waste heat proceeding from alkali furnaces, and
1 provide a second long pan, which I place contiguous to the first-
named pan, but I do not apply any heat by fire to such second pan.

page_text: I provide a channel of communication between the said two pans at
the end most distant from the part where heat is first applied to the
first pan, and having introduced a suitable quantity of "black ash
liquors" into the said two pans, and heat being applied to the first pan
so as to produce concentration of such liquors, I cause a continued
circulation of the same through the said two pans to be effected by
pumping (or otherwise transferring) liquor from the second pan into the
first pan at the opposite end to that at which the channel of communi-
cation exists. By this arrangement the "black ash liquors" become so
concentrated in the first pan as to contain more salts when in a licated
state than they can retain in solution at a lower temperature; there-
fore as the liquors flow through the second pan (and their temperature
becomes reduced) salts are deposited in such second pan, and the
liquors circulate again through the first pan to undergo a further con-
centration. A proper supply of fresh "black ash liquors" is introduced
into the first pan to keep up a suitable quantity in the apparatus. By
means of this arrangement the concentration of black ash liquors, and
the deposition of salts therefrom, can be so effected that no salts, or
only a small quantity of salts, become deposited in the pan to which
heat is applied, such salts being all, or nearly all, collected in the
second or cooler pan, from which such salts can be conveniently
removed; and when the concentration has arrived at such a point that
the mother liquors contain such a proportion of ferro-cyanide of sodium
or of caustic soda, or of both these compounds, as to make it suitable
to separate one or both of these compounds therefrom. I transfer
such mother liquors from such apparatus to other apparatus to effect
such separation.
I have herein-before referred to my improved mode of concentrating
liquors, which I prefer to employ when I wish to obtain caustic soda
in a marketable state, as one of the results of the manufacture of alkali
from common salt. I will now describe this part of my Invention. I
provide an oblong vertical tower made of iron plates, and I adapt in
the inside of such tower a number of iron shelves, placed at such an
inclination that fluid will flow freely down the same. One of these
shelves is attached to one end and to both sides of such tower, but does

page_text: not extend to the other end thereof, leaving a space of about three
inches in width. The next shelf to this is attached to the opposite end
(a few inches below the end of the first-named shelf), and to the two
sides of such tower, but does not extend to the other end thereof,
leaving a space of about three inches in width. In this manner each
alternate shelf is attached to an opposite end of the tower. This
arrangement is such that a supply of fluid being introduced on the
upper part of the first inclined shelf it flows down the same, and is
delivered through the vacant space (before referred to) on to the upper
part of the second inclined shelf, and after flowing over the same it is
delivered to a third shelf, and flows consecutively over such a number
of shelves as have been adapted to such tower. By these means the
fluid employed may be exposed in thin sheets or films to the evapora-
tive action of heated air passing through such tower. I provide an
apparatus of any well-known construction suitable for the production of
a supply of highly heated atmospheric air, and I connect such appa-
ratus with the tower before mentioned at or near its lower part, so that
the supply of heated air may enter therein; and I connect the upper
part of such tower (this being first enclosed) with a strong chimney
draft, and thereby occasion a large quantity of heated air to pass
through such tower. I introduce the fluid (from which I wish to
obtain salts by this improved mode of concentration) into the said
tower in such manner that it becomes distributed nearly equally over
the uppermost shelf, from which it flows nearly equally over the suc-
ceeding shelves, and is exposed to the evaporative action of highly
heated air during such course, and becomes so heated and concen-
trated that it contains more salts than it can retain in solution when
such fluid becomes cooled. I provide a channel of communication
from the lower part of such tower through which the hot concentrated
fluid is conveyed therefrom to two iron pans, through which it flows
and becomes cooled so as to deposit salts, and I elevate the remaining
Huid by a pump or other means from the coolest part of such pans, and
cause it to flow again through such tower. I prefer to apply my
improved mode of concentrating alkaline liquors, for obtaining therefrom
caustic soda in a marketable state, to such liquors as have been

page_text: deprived of a considérable part of the carbonate of soda previously
contained in the "black ash liquors" used, and which liquors contain a
large proportion of caustic soda in solution. I continue the circulation
of the remaining liquors (which are being subjected to this improved
mode of concentration) through the said tower until I find, by testing,
that the remaining liquors are deprived, or nearly deprived, of car-
bonate of soda, when I separate such liquors from the deposited salts,
and I dispose of such liquors as caustic soda in solution, and I subject
such salts to the operations I have herein-before described as suitable for
separating ferro-cyanide of sodium and caustic soda from similar salts.
In place of using a tower provided with shelves, as herein-before
described, for effecting my improved mode of concentrating alkaline
liquors for the production of caustic soda, I can use a tower filled with
coke or other suitable material, through which I cause alkaline liquors
to flow at the same time that a current of heated air also flows through
the same, and by its evaporative action effects such concentration; but
I prefer to use the aforesaid tower provided with shelves, as, if the
evaporation in the tower filled with suitable materials be allowed to
progress too rapidly, a deposition of salts occurs in such tower which
obstructs the passage of heated air through the same, whilst, if such
deposition of salts occur in a tower provided with inclined shelves,
such salts either become washed down by the flow of liquor, and are
collected at the bottom, or, if an accumulation of salts should be
formed on the shelves, this may be removed through apertures pro-
vided in the sides of such tower.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Gossage in the Great Seal Patent Office,
on the 17th November 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
WILLIAM GOSSAGE, of Widnes, in the County of Lancaster, Manu-
facturing Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of May, in the
year of

page_text: our Lord One thousand cight hundred and fifty-three, in the sixteenth
year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said William Gossage, Her special licence that
1, the said William Gossage, my executors, administrators, and assigns,
or such others as I, the said William Gossage, my executors, admi-
nistrators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Chan-
nel Islands, and Isle of Mau, an Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF ALKALI FROM COMMON SALT," upon the condition,
amongst others, that I, the said William Gossage, by an instrument
in writing under my hand and scal, should particularly describe and as-
certain the nature of the said Invention, and in what manner the same
is 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 William Gossage, do hereby de-
clare the nature of my 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):
"
In manufacturing alkali from common salt by the processes or
operations in ordinary use common salt is firstly decomposed by the
action of sulphuric acid, thus producing sulphate of soda, which
product being mixed with small coal and carbonate of lime, and fluxed,
the product thus obtained is known by manufacturers as "rough soda
or black ash." This product being lixiviated with water yields
liquors containing alkali in solution and for the purpose of <lescribing
my Invention I will call these liquors "black ash liquors;" such
liquors being evaporated so as to produce salts, and the product roasted
in a furnace, a dry substance is obtained, which is known in commerce
as soda ash or alkali. For the purpose of manufacturing crystals of
soda it is customary to dissolve soda ash or alkali in water, and to
concentrate the solution to a suitable strength, when it is allowed to
cool and form crystals. All the before-mentioned operations are con-

page_text: ducted very extensively, and are well understood by manufacturers of
alkali.
"Black ash liquors" (as these are obtained in manufacturing alkali
from common salt) usually contain carbonate of soda, caustic soda,
sulphuret of sodium, sulphuret of iron (held in solution by sulphuret
of sodium), and ferro-cyanide of sodium. During the ordinary pro-
cesses of evaporating black ash liquors, and of roasting the salts so
obtained, sulphuret of iron and iron of the ferro-cyanide of sodium
become converted into oxide of iron, and this substance communicates
an objectionable yellow colour to the "soda ash" produced, and renders
it unsuitable for certain applications. One part of my improvements
consists in separating sulphuret of iron from "black ash liquors," and
thereby obtaining liquors capable of yielding "suda ash" or " alkali"
not contaminated with such iron as had previously existed in such
liquors in the state of sulphuret of iron. I will now describe the means
by which I prefer to effect this part of my Invention. I have stated
that sulphuret of iron is held in solution by such liquors by sulphuret of
sodium contained therein, and I have found that when such sulphuret
of sodium is converted by oxydation into hypo-sulphite or sulphite or
sulphate of soda, the sulphuret of iron is no longer soluble in such
liquors, and consequently it separates therefrom when allowed to
subside. I effect such oxydation of sulphuret of sodium contained in
black ash liquors" by causing such liquors to absorb oxygen from
atmospherical air. I prefer to effect such absorption of oxygen by
passing black ash liquors" as uniformly as may be conveniently prac-
ticable through a high tower (made of iron plates or other suitable
material, and which I call an "oxydizing tower,") filled with small
pieces of coke (or other suitable material), supported on a grating
near the bottom of such tower, at the same time that currents of
atmospherical air pass through the interstices existing between such
pieces of coke. When it may be convenient I prefer to close the lower
part of the tower (making provision for running off the liquors), and
to connect it with a powerful chimney draft, and thereby to occasion a
larger quantity of air to be passed through the tower in downward
currents. By means of this arrangement "black ash liquors" (spread

page_text: in thin films over an immense number of surfaces) are presented to
the currents of atmospherical air passing through such tower, and
I
the absorption of oxygen by such liquors is thereby effected.
prefer to cause the quantity of black ash liquors" supplied to the
said oxydizing tower to be so regulated that when the liquors flow
from the lower part of the tower all the sulphuret of sodium
previously contained in such liquors shall have become oxydised,
and consequently the sulphuret of iron previously dissolved in such
liquors shall have become insoluble, and I cause such sulphuret of iron
to be separated from the "black aslı liquors," cither by subsidence or
filtration, and I thus obtain liquors deprived of iron previously contained
therein, as sulphuret of iron, and which liquors I will herein-after desig-
nate as "purified black ash liquors." I find that a circular tower, six feet
diameter, and twenty feet high, filled with pieces of coke of the size of
walnuts, is equal to the purification of as much "black ash liquors" in a
week as will produce from thirty to fifty tons of soda ash. I prefer to apply
this part of my Invention to "black ash liquors," as these are obtained
from the lixiviation of "black ash;" but this part of my Invention
is also applicable to the oxydation of sulphuret of sodium, and separa-
tion of sulphuret of iron contained in black ash liquors," from which
a certain portion of salts have been previously separated by concen-
tration.
When I use such purified black ash liquors" for the production
of soda crystals I prefer to cause the greater part of the caustic soda
contained therein to be converted into carbonate of soda by absorption
of carbonic acid gas, and I concentrate the carbonated liquor to
a strength suitable for the formation of soda by crystallization. I will
herein-after describe the manner in which I prefer to use the "mother
liquors resulting from such crystallization.
When I use such "purified black ash liquors" solely for the pro-
duction of soda ash" I prefer to cause the greater part of the caustic
soda contained therein to be converted into carbonate of soda by
absorption of carbonic acid gas, and I concentrate the "purified black
ash liquors" so as to obtain salts therefrom. I will herein-after describe
the manner in which I prefer to treat such salts previously to using
the same for the production of " soda ash."

page_text: When I use such purified "black ash liquors" for the production of
soda ash," also for obtaining caustic soda in a marketable form, 1
concentrate the purified "black ash liquors" so as to obtain salts there-
from. I will herein-after describe the manner in which I prefer to
treat such salts previously to using the same for the production of "soda
ash," also the manner in which I prefer to treat the mother liquors re-
maining after the separation of such salts from purified "black ash
liquors," so as to obtain caustic soda therefrom iu a marketable form.
I have hicrein-before stated that "black ash liquors" usually contain
ferro-cyanide of sodium, and that the iron of this ferro-cyanide, when
converted into oxide of iron, injures the colour and quality of soda
ash produced from liquors containing such ferro-cyanide. One part
of my improvements consists in obtaining ferro-cyanide of sodium
separately from other salts of soda produced from "black ash liquors"
which have contained such ferro-cyanide, and thereby obtaining salts
for the production of soda ash free (or nearly free) from such compound
of iron, at the same time that I obtain a valuable ferro-cyanide. I will
now describe the means by which I prefer to effect this part of my
Invention. I prefer to use "black ash liquors" for this part of my
improvements which have been previously freed from sulphuret of iron,
but my improvements are also applicable to the separation of ferro-
cyanide of sodium from other "black ash liquors" which contain the
sanic. I have herein-before stated that I use purified black ash
liquors for the production of soda by crystallization. The mother liquors
of such crystallization contain nearly all the ferro-cyanide of sodium
previously existing in the "purified black ash liquors "used. I con-
centrate such mother liquors by evaporation so as to obtain salts there-
from, and I continue such concentration until nearly all the carbonate of
soda previously contained in the mother liquors used has become depo-
sited as salts. I prefer to withdraw from the concentrating apparatus
the salts produced at different stages of the operation. The first portions
of salts deposited contain but little ferro-cyanide of sodium, the second
portions of salts contain more of this compound, and the last portions
contain a considerable proportionate quantity of ferro-cyanide, and
the mother liquors still remaining contain a large proportion of
ferro-cyanide in solution. I separate the ferro-cyanide of sodium

page_text: from such salts by causing the salts to be washed by water, or by
solution of carbonate of soda filtering through the same, and for this
purpose I prefer to employ a series of four vats, arranged on the
same system as the vats which are used by alkali manufacturers for
lixiviating "black ash" on the principle of continuous lixiviation. I
place the salts on perforated false bottoms in these four vats, and I
introduce water or solution of carbonate of soda into the vat containing
salts least impregnated with ferro-cyanide, and the solution produced
(containing carbonate of soda and ferro-cyanide) flows from this vat into
an adjacent vat (wherein it takes up a further portion of ferro-cyanide),
and subsequently it flows into and through the two other vats containing
salts, wherein it becomes still more strongly impregnated with ferro-
cyanide. I continue the introduction of water or solution of carbonate
of soda into the first vat until I find that the salts contained therein.
have become sufficiently deprived of ferro-cyanide to be suitable for
the production of white soda ash of good quality. I then discharge
such washed salts from this first vat, and use the same for the manu-
facture of "soda ash" or "alkali." I refill the vat with salts containing
much ferro-cyanide, and I arrange for this vat then to become the last
of the series. By pursuing this mode of working, the salts (contained
in each vat) successively become those which are least impregnated
with ferro-cyanide, and are subjected to the first action of water or
solution of carbonate of soda. I mix the solutions obtained by such
washing with the mother liquors resulting from the concentrating
operation (before referred to), and if I find, by testing, that such liquors
contain more than ten parts of carbonate of soda for cach one part
of ferro-cyanide of sodium present therein, I concentrate such liquors
by evaporation so as to obtain a further quantity of salts therefrom;
and I continue such concentration and separation of salts until I find,
by testing, that the mother liquors then remaining contain less than
ten parts of carbonate of soda for each one part of ferro-cyanide of
sodium present therein (preferring that the proportion of carbonate of
soda should not exceed five parts for one part of ferro-cyanide). I
prefer to introduce the salts obtained by the concentration lastly herein-
before mentioned into a concentrating apparatus in which "black ash

page_text: liquors are being concentrated for the production of salts, or I wash
these salts in vats, as herein-before described, to separate ferro-cyanide
from them. I collect the liquors herein-before referred to as containing
less than ten parts of carbonate of soda for each one part of ferro-
cyanide, and I mix such liquors with sufficient water and caustic lime
to convert the carbonate of soda contained therein into caustic soda
(assisting such conversion by boiling the mixture). I concentrate the
clear solution thus obtained until the whole, or nearly the whole, of the
ferro-cyanide contained therein becomes separated as salt. Or I separate
such ferro-cyanide, by crystallization, from the concentrated solution of
caustic soda. Or, in place of converting the carbonate of soda (con-
tained in liquors from which I propose to separate ferro-cyanide) into
caustic soda, I.cause such carbonate of soda to be converted into
bi-carbonate or sesqui-carbonate of soda by impregnation with carbonic
acid gas, and I thus obtain a precipitated carbonate of soda of sparing
solubility, from which I obtain the greater part of the ferro-cyanide by
drainage and filtration of water through the bi-carbonate or sesqui-
carbonate. I thus obtain a solution of ferro-cyanide containing a small
proportion of carbonate of soda, and I convert this carbonate of soda
into caustic soda by the use of lime. I separate ferro-cyanide from
such solution containing caustic soda either by salting or by crystalliza-
tion. I refine ferro-cyanide of sodium obtained by either of the modes
of separation herein-before described (by solution with water and
repeated crystallization) until it is sufficiently pure to be suitable for
use in the arts. I transfer the liquors remaining after the separation
of ferro-cyanide from caustic soda, also the bi-carbonate or sesqui-
carbonate of soda remaining after the separation of ferro-cyanide there-
from (when this latter mode of separation has been adopted), to a
concentrating apparatus, in which "black ash liquors" are being con-
centrated for the production of salts.
I have herein-before mentioned certain salts obtained from "purified
black ash liquors," when such liquors are used for the production of
soda ash, without previously obtaining crystals therefrom. The salts
so obtained are impregnated in various degrees with ferro-cyanide of
sodium, according to the stage of concentration at which such salts

page_text: have been separated from the liquors. I subject such salts to the
same process of washing in vats as I have herein-before described
for separating ferro-cyanide of sodium from similar salts; and when I
have thereby obtained solutions containing a suitable proportion of
ferro-cyanide, I subject such solutions (also such suitable solutions as
are separated in the state of mother liquors in the process of salting)
to the same processes for separating ferro-cyanide therefrom as I have
herein-before described as suitable for such purpose, when operating
upon solutions containing carbonate of soda and ferro-cyanide of
sodium. By the means above described I also obtain salts produced
from "black ash liquors" sufficiently deprived of ferro-cyanide to be
suitable for producing white soda ash of good quality.
my
I also prefer
I have herein-before stated that "black ash liquors" usually contain
caustic soda. One part of my improvements consists in separating caustic
soda from the other compounds of soda contained in "black ash liquors,
so as to obtain such caustic soda in a useful form without this being pro-
duced by the action of lime on carbonate of soda. I will now describe
the means by which I prefer to effect this part of my Invention.
I prefer to use "black ash liquors" for this part of Invention
which have been previously freed from sulpliuret of iron.
to convert any hypo-sulphite of soda which may be present in such
purified "black ash liquors" into sulphite or sulphate of soda by
oxydation, which I effect by the gradual addition of hypochlorite of
lime (solution of bleaching powder). I then concentrate such "black
ash liquors" by evaporation, so as to obtain the greater part of the
carbonate of soda (previously contained therein) in the form of salts,
and I thus obtain a quantity of salts, impregnated in various degrees
with caustic soda, and ferro-cyanide of sodium (when the "black ash
liquors" employed have contained ferro-cyanide of sodium). I also
obtain a quantity of mother liquors containing much caustic soda,
some carbonate of soda, and ferro-cyanide of sodium (when this last-
named compound has been present in the liquors employed). I subject
the salts thus obtained to the operation of washing with water, or with
solution of carbonate of soda, by filtration (herein-before described), so
as to obtain salts sufficiently free from caustic soda and ferro-cyanide to
R

page_text: bé suitable for the production of white soda ash of good quality, and
I add the liquors (obtained by such washing) to the mother liquors
above mentioned. I concentrate such mixed liquors, either by incans
of ordinary concentrating pans, or, by preference, by the use of my
improved mode of concentration (berein-after described), until the
whole, or nearly the whole, of the carbonate of soda and ferro-cyanide
of sodium (previously existing in such mixed liquors) have become
deposited as salts, and the solution or mother liquor remaining (which
will then have acquired a specific gravity of about 1-450) contains
scarcely any saline matter in solution, except caustic soda. In the
state it is thus obtained caustic soda is particularly suitable for the
manufacture of soap, and for many other applications. By further
concentrating the solution of caustic soda in cast iron pans it can
be so far deprived of water as to become solid hydrate of soda, when
allowed to cool, and in this state it presents great facilities for trans-
portation. The salts obtained by the concentration of such "mixed
liquors," herein-before mentioned, are impregnated in various degrees
with ferro-cyanide of sodium and caustic sola, and I subject these salts
to the operation of washing with water, or with solution of carbonate
of soda, by filtration, herein-before described, so as to separate ferro-
cyanide of sodium and caustic soda therefrom; and I prefer to dis..
continue such washing before the whole of the ferro-cyanide has been
separated from the salts, and to transfer the washed salts from the vats
to a concentrating apparatus in which "black ash. liquors are being
concentrated for "the production of salts. I examine the liquors
obtained by such washing, and if these liquors are found to contain
more than five parts of carbonate of soda for each one part of ferro-
cyanide of sodium contained therein, I subject such liquors to a further
process of concentration, so as to obtain salts therefrom, also liquors
containing a larger proportionate quantity of ferro-cyanide; but if such
liquors contain less than five parts of carbonate of soda for each one
part of ferro-cyanide of sodium contained therein, I convert such
carbonate of soda into caustic soda by means of lime & water
(assisted by ebullition), and I concentrate the solution thus obtained
until the whole, or nearly the whole, of the ferro-cyanide previously

page_text: contained therein is deposited as salt. I purify this salt by solution and
crystallization. as herein-before mentioned for similar salt.
I have herein-before referred to my improved mode of concentrating
liquors, which I prefer to employ when I wish to obtain caustic soda in
a marketable state from "black ash liquors." I will now describe this
part of my Invention, which consists in arrangements by means of
which I
expose "black ash liquors" in films or sheets to the evaporative
action of heated air. I provide an oblong vertical tower (measuring
about six feet in length, four feet in width, and twenty feet in height)
made of iron plates, and I adapt in the inside of such tower a number
of iron shelves or partitions, placed at an inclination of about fifteen
degrees with the horizon, so that liquor will flow down the same. .One
of these shelves is attached to one end and to both sides of such tower,
but does not extend to the other end thereof, leaving an open space of
about six inches in width. The next shelf or partition below this.
is attached to the opposite end (about four inches below the lower.
end of the shelf or partition before mentioned) and to the two sides, of
such tower, and is placed at a similar inclination to the horizon,.but
does not extend to the other end thereof, leaving an open space of
about six inches in width. In this manner each alternate shelf
or partition is attached to an opposite end of the tower, and the-
number of shelves or partitions is as many as the tower will admit.
of being so placed therein. This arrangement is such that a supply of
liquor being introduced on the upper part of the first inclined shelf
or partition, it flows down the same, and is delivered (through the
vacant space before referred to) on to the upper part of the second
inclined shelf or partition, and, after flowing over the same, it is deli--
vered to a third shelf or partition, and flows consecutively over 'such
a number of shelves or partitions as have been adapted to such tower,.
and, finally, becomes collected at the bottom thereof. By means of this.
arrangement liquor may be exposed in thin sheets or films to the.
evaporative action of heated air passing through such tower. I provide.
an apparatus (of any well-known construction) suitable for the 'pro-
duction of a supply of highly heated air, and I connect such apparatus

page_text: with the tower before mentioned at or near its lower part, so that the
supply of heated air may enter therein, and I connect the upper part of
such tower (the top being covered) with a strong chimney draft, and
I thereby occasion a large quantity of heated air to ascend through
such tower. I introduce liquor (which I wish to subject to this im-
proved mode of concentration) into the said tower in such manner
that it becomes distributed nearly equally over the uppermost shelf or
partition, from which it flows nearly equally over the succeeding shelves
or partitions, and is exposed to the evaporative action of highly heated
air during such course, and becomes thereby so concentrated that it
contains more salts than it can retain in solution when such liquor
becomes cooled.
I provide a channel of communication from the lower part of such
tower, through which the hot concentrated liquor is conveyed therefrom
to one or more iron pans, through which it flows and becomes cooled
so as to deposit salts, and I elevate the remaining liquor by a pump, or
other suitable means, from the coolest part of such pan or pans, and
cause it to flow again through such tower. I prefer to apply my
improved mode of concentrating "black ash liquors" (for obtaining
therefrom caustic soda in a marketable state) to such liquors as have
been deprived of a considerable part of the carbonate of soda previously
contained therein, and which liquors contain a large proportion of
caustic soda in solution. I continue the circulation of the remaining
liquors (which are being subjected to this improved mode of concentra-
tion) through the said tower until I find, by testing, that the remaining
liquors are deprived, or nearly deprived, of carbonate of soda, when
I separate such liquors from the deposited salts, and I dispose of such
liquors as solution of caustic soda, and I subject such salts to the
operations I have herein-before described as suitable for separating
ferro-cyanide of sodium and caustic soda from similar salts.
་་
I have herein-before described and fully explained certain means by
which I prefer to carry into effect my "Invention of "Improvements
in the Manufacture of Alkali from Common Salt," but I do not confine
myself to the employment of the exact means herein described, as these

page_text: may be varied to some extent without deviating from the nature of my
Invention, which Invention consists,―
Firstly, in oxylizing "black ash liquors" by exposing such liquors in
a state of minute division to the action of atmospherical air.
Secondly, in separating "ferro-cyanide of sodium" from other com-
pounds of soda contained in "black ash liquors," and also thereby
obtaining salts of soda free, or nearly free, from such ferro-cyanide.
Thirdly, in obtaining "caustic soda" from "black ash liquors" by
concentration, and without the use of line.
Lastly, in an improved mode of effecting the concentration of
"black ash liquors" by presenting such liquors in thin sheets or films
to the evaporative action of heated air for the purpose of obtaining
caustic soda therefrom..
In witness whereof, I, the said William Gossage, have hereunto
set my hand and seal, this Sixteenth day of November, One
thousand eight hundred and fifty-three.
Witness, JOHN MOORE,
Accountant, Widnes.
WILLIAM GOSSAGE. (L.S.)