IMPROVEMENTS IN THE MANUFACTURE OF SODA AND IN THE PROCESSES EMPLOYED THEREFOR.
Year: 1877

page_text: LETTERS PATENT to Henry Bollmann Condy, of Battersea, in the County of
Surrey, Chemist, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF SODA AND IN THE PROCESSES EMPLOYED THEREFOR.'
1011
"
"
PROVISIONAL SPECIFICATION left by the said Henry Bollmann Condy at
the Office of the Commissioners of Patents on the 19th April 1877.
HENRY BOLLMANN CONDY, of Battersea, in the County of Surrey, Chemist.
"IMPROVEMENTS IN THE MANUFACTURE OF SODA AND IN THE PROCESSES EMPLOYED
THEREFOR."
This Invention is for an improved process for the manufacture of carbonate of
soda and bicarbonate of soda, and has for its object the increase of the product and
the utilization or recovery of some of the materials used in the manufacture. This
process may be shortly described; it consists,-
First. In the reduction of sulphate of soda, mixed with carbon, to the state of
sulphide of sodium.
Second. In the decomposition and conversion of sulphide of sodium into super-
carbonated, or, as I should prefer, bicarbonate of soda, by means of carbonic acid.
Third. The recovery of the sulphur evolved as sulphuretted hydrogen in this
process in a useful form, either alone or in combination with iron, or its use in the
manufacture of sulphuric acid.
And, Fourth. The utilization of the carbonic acid contained in the super-
carbonated or bicarbonate of soda obtained in this process.
The mode in which I proceed is as follows:-I take 300 parts of sulphate of soda
and 100 parts of small coal, coke, or other suitable form of carbon, both of which
I prefer to grind and thoroughly mix; after which I introduce the mixture into an
iron or other suitable cylinder or retort, chamber, or vessel from which atmospheric
air is excluded and which should be set in a furnace, so as to be heated to about a
red heat by coal or other fuel, and I keep the mixture confined to this retort or
chamber and occasionally moved by an agitator or other contrivance, or the retort
itself may be revolved until I find by testing samples taken from the mixture that
it is free, or nearly free, from sulphate of soda.
"

page_text: The material when removed from the cylinder, or retort, or chamber, consists of
sulphide of sodium, with a little excess of sulphur, carbonized coal, and small
per-centage of chemical impurities originally present in the sulphate of soda and
coal.
I take the sulphide of sodium produced, as described, and operate on it in one
of three methods, that is to say :-
First. I deal with the crude mass as taken from the cylinder, to which I add
water in the proportion of 3 lbs. of water to 2 lbs. of the crude sulphide. The
mixture becomes warm and liquefies, and is then to be put aside until it solidifies;
the effect being that the water enters into combination with the sulphide of sodium,
and there is formed a roughly made crystallized sulphide.
Or, Second. I dissolve the sulphide out of its insoluble impurities and evaporate
the solution to its crystallizing point, when I leave it to cool and crystallize, after
which I draw off the mother liquor which I subsequently evaporate again to the
crystallizing point to obtain a fresh crop of crystals.
Or, Third. I dissolve the sulphide out of its insoluble impurities and evaporate
the solution, boiling away all the rest of the water till that point is reached, when
the contents of the evaporator consist of about 60 to 67 per cent. of water, the rest
being sulphide of sodium. The contents of the evaporator are then removed and
allowed to solidify; the water combining with the sulphide forms a roughly
crystallized mass of sulphide of sodium.
These various operations of evaporating and crystallizing I prefer to conduct in
vessels from which atmospheric air is as much as possible excluded, my object being
to prevent the oxidation of the sulphide of sodium. Of these methods I prefer
either the 2nd or the 3rd, as they furnish a purer carbonate of soda.
I consider an important improvement in my process to consist in the use of
crystallized sulphide of sodium, which contains about 67 per cent. of water; or of
dried sulphide of sodium treated or wetted, so that it shall contain the same or
nearly the same proportion of water; or of sulphide of sodium obtained by evapo-
rating a solution to such a point that it shall contain about 60 to 67 per cent. of
water, so as to enable it to form a mass of rough crystals on cooling. I place the
sulphide of sodium, whether regularly crystallized or obtained, in the roughly
crystallized amorphous mass before described on a perforated false bottom in a
chamber into which I introduce (by preference under the false bottom) a stream of
carbonic acid. The false bottom should be placed about four inches from the actual
bottom of this chamber. This chamber should be closed to atmospheric air, and
it will be convenient to construct it in the following manner, that is:-Having only
four openings, one immediately under the false bottom for the entry of carbonic
acid, one at the upper part for the exit of sulphuretted hydrogen; a third at the
bottom for withdrawing the excess of water, which trickles down in the operation,
saturated with soda salts; and a fourth near the top through which to obtain
samples, so as to check the operation and ascertain its progress. I continue to
supply this chamber with carbonic acid until I find by testing by methods well
known to all chemists that specimens taken from the top when tested show the
absence of sulphide of sodium, which is a proof of the completion of the conversion
into carbonate of soda with excess of carbonic acid.
In practice I find great advantage result from employing several chambers con-
nected with each other in such a way that the carbonic acid which may escape
uncombined with soda from one chamber may pass from the upper part of the first
to the lower part of the second chamber, and from the upper part of the second
chamber to the lower part of a third, and so on. For this purpose I prefer to
employ at least five such chambers, and with the object of rendering most effective
the carbonic acid I prefer, between each chamber, to reduce to sulphur the sul-
phuretted hydrogen which accompanies it by the plan hereafter described. The
result will be the conversion of sulphide of sodium into super-carbonated or bicar-
bonate of soda.
Having succeeded in decomposing the sulphide of sodium by saturating it with

page_text: carbonic acid, I remove the mass from the chamber; if thoroughly saturated, I find
it to consist of bicarbonate of soda combined with a small amount of impurity. If
I wish to produce simple carbonate of soda, I heat this mass in a suitable closed
vessel to expel the excess of carbonic acid, which I utilize (after cooling it) in the
decomposition of sulphide of sodium in a subsequent operation by the method
already described, and I find the material after being thus heated to consist of
nearly pure carbonate of soda if made from sulphide of sodium treated by the 2nd
or 3rd plans, but if made by the 1st it contains impurities from which it must be
freed by dissolving it in water. This part of the process may be varied in this way,
that is to say, the supercarbonated soda may be dissolved out and the excess of
carbonic acid may be expelled by boiling down the solution, and collected for use
after cooling and condensing in a refrigerator the vapour of water which accom-
panies it. This plan is not the preferable one on account of its extra cost (as
bicarbonate of soda is not very soluble in water), except in those cases in which the
crude undissolved sulphide has been used, and then only if it be required that
mere traces of sulphur should be absent in the soda ash. The carbonato of soda
thus obtained is called in commerce soda ash, but made from sulphide of sodium
treated by the 2nd and 3rd methods, being nearly pure, it has a higher per-centage
of soda than is contained in ordinary soda ash. For the production of crystallized
carbonate it is only necessary to dissolve it in water, and set it aside to cool and
crystallize in the usual manner known to soda makers and chemists.
The next part of my process consists in the recovery of sulphur from the
sulphuretted hydrogen evolved in the process already described, which I effect in
one of two conditions, that is to say, either, 1st, as sulphur, or 2nd, in combination
with iron as a sulphide of iron. 1st, in the former case, I pass the sulphuretted
hydrogen, whether mixed or unmixed with carbonic acid, into a vessel containing a
salt of peroxide of iron, which I prefer to use in the state of solution; I find the
effect to be that the hydrogen of sulphuretted hydrogen is oxidized at the expence
of the peroxide of iron, the solution of persalt of iron is reduced to protoxide, and
sulphur is precipitated in such a condition that after being well washed with water
it can be used for any purpose wherein sulphur is required, or it can be converted
into commercial sulphur by being melted and cooled. 2nd, in the second case, that
is, the recovery of the sulphur as sulphide, I pass the sulphuretted hydrogen into a
chamber containing sesquioxide of iron until the latter is saturated with sulphur,
I then remove the sulphide of iron thus formed, expose the product to the air, so
that the sulphide of iron may be re-oxidized, and thus reproduce the sesquioxide of
iron, which can be again employed for fixing a further quantity of sulphuretted
bydrogen, and the exposure of the sulphide of iron again repeated, and the sesqui-
oxide of iron again employed several successive times, or until its activity is
sensibly diminished by being clogged with too much sulphur. When this latter
condition has been attained, I burn the sulphur iron mixture in a suitable furnace
for the production of sulphurous acid to be used in the manufacture of sulphuric
acid by the method well known to all sulphuric acid makers; or I dry the mixture
and dissolve out the free sulphur in bisulphide of carbou, distil the bisulphide of
carbon, and obtain sulphur as a residue in the still; or I dissolve out the iron and
have sulphur recovered.
Another mode of utilizing the sulphuretted hydrogen is to burn it in contact
with atmospheric air for the production of sulphurous acid, which can be converted
by the well known method into sulphuric acid, or be used for any purpose for
which sulphurous acid itself inay be required or used.
I am aware it was proposed by one person to treat sulphide of sodium in the
solid state by carbonic acid, and to produce simple carbonate of soda; but this
ethod is not in practice, and after careful trial I have found it unsuccessful.
I am also aware that sulphuretted hydrogen is removed from illuminating gas
by means of peroxide of iron, and that it was proposed by the same person to
recover the sulphur from the sulphuretted hydrogen evolved in his process above
referred to, and which does not succeed, by nieans of peroxide of iron; and this is

page_text: not a new application of peroxide of iron, except so far as my process is concerned,
and I am not aware that it has ever been put into practice, the reason being I
believe that the former part of the process is impracticable. I am thus enabled to
manufacture soda without requiring other materials than salt and fuel, together
with a small quantity of sulphur and carbon to compensate for unavoidable
losses.
The persalts of iron, which I consider to be the most suitable for the recovery of
pure sulphur, are the persulphate or perchloride, which, after utilizing for this
purpose, which reduces them to the state of protosulphate and protochloride
respectively, I proceed to recover in their active condition ns persalts for sub-
sequent re-employment in the reduction of a further quantity of sulphuretted
hydrogen. I repeat the process of recovering the persalts and re-employment for
this purpose as often as may be required.
The methods I employ for obtaining persulphate or perchloride of iron are
founded on the necessity of recovery in a useful form the materials employed,
whichever of these salts may be used in a fit state for subsequent re-employment
or for sale. I would first describe my method of making and dealing with the per-
chloride of iron, and next with the persulphate. In the first place I dissolve any
cheap or waste peroxide of iron (such as that resulting from the combustion of iron
pyrites or native iron ore rich in peroxide) in hydrochloric acid, and I employ the
solution thus formed in my first operation for the recovery of sulphur. After its
decomposition by sulphuretted hydrogen, sulphur is precipitated in the liquid,
which latter is, reduced te protochloride of iron.
The solution of protochloride of iron being filtered out is treated with a sufficient
quantity of caustic magnesia to precipitate the iron as protoxide, the chloride of
magnesium which forms the supernatant liquid is decanted, and the precipitate of
protoxide of iron is again peroxidized, either by driving atmospheric air through
it, suspended in water, or by draining and exposing it to the action of atmospheric
air, and turning it over frequently in a dry or nearly dry state, so as to expose fresh
surfaces to the action of the atmosphere until it is completely peroxidized. The
solution of chloride of magnesium is evaporated to dryness, and steam is driven
through the dry mass. The hydrochloric acid is liberated in the form of vapour
and condensed in the usual manner; the residue, after expelling the hydrochloric
acid, consists principally of caustic magnesia. By these means the various
substances required for the reduction of sulphuretted hydrogen are recovered in the
condition required for their re-employment for the same purpose, namely, per-
chloride of iron, by means of dissolving the peroxide recovered as first described, is
the hydrochloric acid recovered in the decomposition of chloride of magnesium, and
the magnesia which is required for the precipitation of the protochloride of iron
which results from the decomposition of the per-chloride by means of sulphuretted
hydrogen.
In making and dealing with persulphate of iron when that salt is employed I
proceed as follows:-I dissolve any native or waste peroxide of iron in sulphuric
acid, and dilute it with three or four times its volume of water. After passing the
sulphuretted hydrogen through it, it is reduced to protosulphate with excess of
acid. This solution of protosulphate of iron filtered or separated from the precipi-
tated sulphur I treat with caustic magnesia, by which means I precipitate protoxide
of iron and obtain a solution of sulphate of magnesia. I filter the latter from the
former and evaporate to the crystallizing point, when I set it aside to crystallize
and obtain sulphate of magnesia, commonly known as Epsom salts. The protoxide
of iron from which it is filtered is to be recovered as peroxide by either of the plans
before described.
To obtain the supply of caustic magnesia originally required in this process
prefer to use that substance obtained by the ignition of native carbonate of
magnesium. If it should be preferred to save the trouble of recovering peroxide
of iron and to sell the precipitated protoxide, then in such case I make use in all
cases (for the production of perchloride or persulphate of iron) of any form of cheap

page_text: or waste peroxide of iron, such as that resulting from burning pyrites or of native
iron ore rich in peroxide of iron. And to obtain a supply of carbonic acid for the
decomposition of sulphide of sodium it is only needful to point to the well-known
plans of generating this gas by the action of hydrochloric acid on chalk or carbonate
of lime, of obtaining it by the combustion of coke or charcoal, freeing the carbonic
acid from atmospheric air, or of expelling it from chalk or marble by heating them
in a closed cylinder or vessel.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Bollmann Condy in the Great Seal Patent Office on the 18th
October 1877.
HENRY BOLLMANN CONDY, of Battersea, in the County of Surrey. " IMPROVE-
MENTS IN THE MANUFACTURE OF SODA AND IN THE PROCESS EMPLOYED THEREFOR."
This Invention is for an improved process for the manufacture of carbonate of
soda and bicarbonate of soda, and has for its object the increase of the product, and
the utilization or recovery of some of the materials used in the manufacture. This
process may be described as follows: It consists,—
First. In the reduction of sulphate of soda mixed with carbon to the state of
sulphide of sodium.
Second. In the decomposition and conversion of sulphide of sodium into super-
carbonated, or, as I should prefer, bicarbonate of soda, by means of carbonic acid.
Third. The recovery of the sulphur evolved as sulphuretted hydrogen in this
process in a useful form, either alone or in combination with iron or its use in the
manufacture of sulphuric acid.
And, Fourth. The utilization of the carbonic acid contained in the supercarbonated
or bicarbonate of soda obtained in this process.
The mode in which I proceed is as follows:-I take 300 parts of sulphate of
soda and 100 parts of small coal, coke, or other suitable form of carbon, both of
which I prefer to grind and thoroughly mix, after which I introduce the mixture
into a suitable cylinder, or retort chamber, or vessel, from which atmospheric air is
excluded, aud which should be set on a furnace, so as to be heated to about a red
heat by coal or other fuel, and I keep the mixture confined to this retort or chamber
and occasionaly moved by an agitator or other contrivance, or the retort itself may
be revolved, until I find by testing samples taken from the mixture that it is free or
nearly free from sulphate of soda.
The material when removed from the cylinder, or retort, or chamber, consists of
sulphide of sodium, with a little excess of sulphur, carbonized coal, and a small
per-centage of chemical impurities originally present in the sulphate of soda and coal.
I take the sulphide of sodium produced as described and operate on it in one of
three methods, that is to say :-
First. I deal with the crude mass as taken from the cylinder, to which I add water
in the proportion of 3 lbs. (pounds) of water to 2 lbs. (pounds) of the crude sulphide.
The mixture becomes warm and liquifies, and is then to be put aside until it solidifies,
the effect being that the water enters into combination with the sulphide of sodium
and there is formed a roughly made crystallized sulphide.
Or, Second. I dessolve the sulphide out of its insoluble impurities, and evaporate
the solution to its crystallizing point, when I leave it to cool and crystallize, after
which I draw off the mother liquor, which I subsequently evaporate again to the
crystallized point, to obtain a fresh crop of crystals.
Or, Third. I dissolve the sulphide out of its insoluble impurities and evaporate
the solution, boiling away all the rest of the water till that point is reached when
the contents of the evaporator consist of about 60 to 67 per cent. of water, the rest
being sulphide of sodium. The contents of the evaporator are then removed and
allowed to solidify; the water combining with the sulphide forms a roughly
crystallized mass of sulphide of sodium.
These various operations of evaporating and crystallizing I prefer to conduct in

page_text: vessels from which atmospheric air is as much as possible excluded, my object being
to prevent the oxidation of the sulphide of sodium.
I consider an important improvement in my process to consist in the use of
crystallized sulphide of sodium, which contains about 67 per cent. of water, or of
dried sulphide of sodium treated or wetted so that it shall contain the same or
nearly the same proportions of water of crystallization, or of sulphide of sodium
obtained by evaporating a solution to such a point that it shall contain about 60 to
67 per cent. of water, so as to enable it to form a mass of rough crystals on cooling.
I place the sulphide of sodium, whether regularly crystallized or obtained in the
roughly crystallized amorphous mass, as before described, on a perforated false
bottom in a chamber, into which I introduce (by preference, under this false bottom)
a stream of carbonic acid. The false bottom should be placed about four inches
from the actual bottom of this chamber; this chamber should be closed to atmos-
pheric air, and it will be convenient to construct it in the following manner, that is,
having only four openings, one immediately under the false bottom for the entry of
carbonic acid, one at the upper part for the exit of sulphuretted hydrogen, a third
at the bottom for withdrawing the excess of water which trickles down in the
operation, saturated with soda salts, and a fourth near the top through which to
obtain samples so as to check the operation and ascertain its progress. I continue to
supply this chamber with carbonic acid, until I find by testing, by methods well
known to all chemists, that specimens taken from the top, when tested, show the
absence of sulphide of sodium, or only traces thereof, which is a proof of the
completion of the conversion into carbonate of soda with excess of carbonic acid.
In practice I find great advantage result from employing several chambers con-
nected with each other in such a way that the carbonic acid which may escape
uncombined with soda from one chamber may pass from the upper part of the first
to the lower part of a second chamber, and from the upper part of the second
chamber to the lower part of a third, and so on. For this purpose I prefer to
employ at least five such chambers, and with the object of rendering most effective
the carbonic acid, I prefer between each chamber to reduce to sulphur the
sulphuretted hydrogen which accompanies it by the plan herein-after described.
The result will be the conversion of sulphide of sodium into supercarbonated or
bicarbonate of soda.
Having succeeded in decomposing the sulphide of sodium by saturating it with
carbonic acid I remove the mass from the chamber; if thoroughly saturated I find it
to consist of bicarbonate of soda combined with a certain amount of impurity. If
I wish to produce simple carbonate of soda, I heat this mass in a suitable closed
vessel to expel the excess of carbonic acid, which I utilize (after cooling it) in the
decomposition of sulphide of sodium in a subsequent operation by the method
already described, and I find the metarial after being thus heated to consist of
nearly pure carbonate of soda, if made from sulphide of sodium treated by the
second and third plans; but if made by the first, it contains impurities from which
it must be freed by dissolving it in water. This part of the process may be varied
in this way, that is to say, the supercarbonated soda may be dissolved out, and the
excess of carbonic acid may be expelled by boiling down the solution, and collected
for use after cooling and condensing in a refrigerator the vapour of water which
accompanies it. This plan is not the preferable one, on account of its extra cost (as
bicarbonate of soda is not very soluble in water) except in those cases in which the
crude undissolved sulphide has been used, and then only if it be required that mere
traces of sulphur should be absent in the soda ash. The carbonate of soda thus
obtained is called in commerce soda ash; but made from sulphide of sodium treated
by the second and third methods, being nearly pure, it has a higher per-centage of
soda than is contained in ordinary soda ash. For the production of crystallized
carbonate it is only necessary to dissolve it in water and set it aside to cool and
crystallize in the usual manner known to soda makers and chemists.
The next part of my process consists in the recovery of sulphur from the
sulphuretted hydrogen evolved in the process already described, which I effect in

page_text: one of two conditions, that is to say, either first as sulphur, or second in combination
with iron as a sulphide of iron. First, in the former case I pass the sulphuretted
hydrogen into a vessel containing a salt of peroxide of iron, which I prefer to use in
the state of solution; I find the effect to be that the hydrogen of sulphuretted
hydrogen is oxidised at the expence of the peroxide of iron, the solution of persalt
of iron is reduced to protoxide, and sulphur is precipitated in such a condition, that
after being well washed with water it can be used for any purpose wherein sulphur
is required, or it can be converted into commercial sulphur by being melted and
cooled; second, in the second case, that is, the recovery of sulphur by means of the
oxide of iron, I pass the sulphuretted hydrogen into a chamber containing sesque-
oxide of iron, by preference in the hydrated condition, until the latter is saturated
with sulphur, I then remove the sulphide of iron thus formed, expose the product to
the air, so that the sulphide of iron may be re-oxidized, and thus reproduce the
sesqueoxide of iron, which can again be employed for fixing a further quantity of
sulphuretted hydrogen, and the exposure of the sulphide of iron again repeated and
the sesqueoxide of iron again employed several successive times, or until its activity
is sensible diminished by being clogged with too much sulphur. When this latter
condition has been attained, I burn the sulphur-iron mixture in a suitable furnace
for the production of sulphurous acid, to be used in the manufacture of sulphuric
acid by the method known well to sulphuric acid makers, or I dry the mixture and
dissolve out the free sulphur in bisulphide of carbon, distil the bisulphide of carbon,
and obtain sulphur as a residue in the still; or I dissolve out the iron by an acid and
leave sulphur recovered.
Another mode of utilizing the sulphuretted hydrogen is to burn it in contact with
atmospheric air for the production of sulphurous acid, which can be converted by
the well-known method into sulphuric acid, or be used for any purpose for which
sulphurous acid itself may be required or used.
I am aware it has been proposed to decompose sulphide of sodium by means of
carbonic acid, but not in the condition or in the manner described.
I am also aware that sulphuretted hydrogen is removed from illuminating gas by
means of peroxide of iron, and that it has been proposed to recover the sulphur from
sulphuretted hydrogen derived from other sources by the same means, and I do not
claim the discovery of this chemical reaction.
The persalts of iron which I consider to be the most suitable for the recovery of
pure sulphur are the persulphate or perchloride, which after utilizing for this purpose
which reduces them to the state of protosulphate and protochloride respectively, I
proceed to recover in their active condition as persalts for subsequent re-employment
in the reduction of a further quantity of sulphuretted hydrogen; I repeat the
process of recovering the persalts and re-employment for this purpose as often as
may be required.
The method I employ for obtaining persulphate or perchloride of iron is founded
on the necessity of recovering in a useful form the materials employed, whichever of
theso salts may be used, in a fit state for subsequent re-employment or for sale. I
would first describe my method of making and dealing with the perchloride of iron
and next with the persulphate. In the first place I dissolve any cheap or waste
peroxide of iron (such as that resulting from the combustion of iron pyrites or
native iron ore rich in peroxide) in hydrochloric acid, and I employ the solution thus
formed in my first operation for the recovery of sulphur. After its decomposition
by sulphuretted hydrogen, sulphur is precipitated in the liquid, which latter is
reduced to protochloride of iron.
The solution of protochloride of iron being filtered out, is treated with
a sufficient quantity of caustic magnesia to precipitate the iron as protoxide,
the chloride of magnesium which forms the supernatant liquid is decanted,
and the precipitate of protoxide of iron is again peroxidized either by driving
atmospheric air through it, suspended in water or by draining, and exposing
it to the action of atmospheric air, and turning it over frequently in a dry or nearly
dry state, so as to expose fresh surfaces to the action of the atmosphere until it is

page_text: completely peroxidized. The solution of chloride of magnisium is evaporated to
dryness and steam is driven through the dry mass. The hydrocloric acid is
liberated in the form of vapour and condensed in the usual manner, the residue after
expelling the hydrocloric acid consists principally of caustic magnasia. By these
means the various substances required for the reduction of sulphuretted hydrogen
are recovered in the condition required for their re-employment for the same pur-
pose, viz., perchloride of iron, by means of dissolving the peroxide recovered, as
hercin-before described in the hydrochloric acid recovered in the decomposition of
chloride of magnesium and the magnesia which is required for the precipitation of
the protochloride of iron which results from the decomposition of the perchloride by
means of sulphuretted hydrogen.
In making and dealing with persulphate of iron when that salt is employed I
proceed as follows:-I dissolve any native or waste peroxide of iron in sulphuric
acid, and dilute it with three or four times its volume of water; after passing the
sulphuretted hydrogen through it, it is reduced to protosulphate with excess of acid.
This solution of protosulphate of iron filtered or separated from the precipitated
sulphur I treat with caustic magnesia, by which means I precipitate protoxide of
iron and obtain a solution of sulphate of magnesia; I filter the latter from the
former and evaporate to the crystallizing point, when I set it aside to crystallize
and obtain sulphate of magnesia commonly known as Epsom salts. The protoxide
of iron from which it is filtered is to be recovered as peroxide by either of the plans
before described.
To obtain the supply of caustic magnesia originally required in this process, I
prefer to use that substance obtained by the ignition of native carbonate of mag-
nesium. If it should be preferred to save the trouble of recovering.peroxide of iron
and to sell the precipitated protoxide, then in such case I make use in all cases (for
the production of perchloride or persulphate of iron) of any form of cheap or waste
peroxide of iron, such as that resulting from burning pyrites or of native iron ore
rich in peroxide of iron. And to obtain a supply of carbonic acid for the decom-
position of sulphide of sodium, it is only needful to point to the well-known means
of generating this gas by the action of hydrochloric acid on chalk or carbonate of
lime, of obtaining it by the combustion of coke or charcoal, freeing the carbonic acid
from atmospheric air, or of expelling it from chalk or marble by heating them in a
closed cylinder or vessel.
My object in all these various operations is to carry out the manufacture of soda
without requiring other materials than salt, fuel, and carbonic acid, whether obtained
from chalk or carbon, together with a small quantity of the following substances to
compensate for waste, viz. :-Sulphur, iron, or oxide of iron, and for dissolving the
iron and magnesia.
Having now described the nature of my said Invention, together with the manner
of performing the same, I would have it distinctly understood in conclusion that
what I claim as new and as of my Invention is, a process for manufacturing
carbonate of soda or bicarbonate of soda by the use of crystallized sulphide of
sodium decomposed by carbonic acid, employed in excess of the quantity required
to make the simple carbonate of soda, the whole to be used in the manner and for
the purpose as herein substantially described and set forth.
In witness whereof, I, the said Henry Bollmann Condy, have hereunto set
my hand and seal, this Twelfth day of October, in the year of our Lord One
thousand eight hundred and seventy-seven
Witness,
THOMAS WRIGLEY,
75, Chancery Lane, W.C.
HENRY BOLLMANN CONDY. (L.S.)