IMPROVEMENTS IN THE MANUFACTURE OF CAUSTIC AND CARBONATED POTASH AND SODA
Year: 1854

page_text: LETTERS PATENT to Louis Joseph Frédéric Margueritte, Chemist, of
Paris, in the Empire of France, and of 16, Castle Street, Holborn (City),
London, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
CAUSTIC AND CARBONATED POTASH AND SODA."
Sealed the 18th May 1855, and dated the 22nd December 1854.
PROVISIONAL SPECIFICATION left by the said Louis Joseph Frédéric
Margueritte at the Office of the Commissioners of Patents, with his
Petition, on the 22nd December 1854.
I, LOUIS JOSEPH FRÉDÉRIC MARGUERITTE, Chemist, of Paris, in the Empire
of France, and of 16, Castle Street, Holborn (City), London, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN THE MANU-
FACTURE OF CAUSTIC AND CARBONATED POTASH AND SODA" to be as follows:-
These improvements consist in using phosphoric or pyrophosphoric acid in
the manufacture of potash and of soda in the following manner :-I treat, with
a suitable quantity of sulphuric acid, phosphate of lime, which may be obtained
by calcination of bones, by precipitation of urinous matter, or in any other
suitable way. Thus, a precipitate of sulphate of lime and of free phosphoric
acid is obtained, which holds a certain quantity of lime in solution. The
phosphoric acid liquor, having been separated from the precipitate, is mixed
with a determinate quantity of common salt, or chloride of sodium, or else
chloride of potassium, if potash is to be obtained. This mixture is then
evaporated and calcined in analogous apparatus to those that are used in

page_text: making sulphate of soda. The chlorhydric acid resulting from this operation is
collected, and the calcined residue, which consists of phosphate or rather
pyrophosphate of soda, is treated with water. To this solution is added lime-
water until precipitation ceases, that is to say, until all the phosphoric acid be
eliminated in the shape of phosphate of lime, having the following composi-
tion: Ph. 0, 2 Ca. O, taking care, however, to avoid any excess, lest further
decomposition of the lime should cause any waste of sulphuric acid, on account
of the operation reproducing itself continuously by the regeneration of the
phosphate of lime. The liquor which rises to the surface of the precipitate is
a solution of caustic soda, which may directly be used for soap making and
other manufactures. To render this soda caustic, it has to be evaporated by
the usual means until it is solidified.
The carbonate of soda may be obtained in different ways; first, by forming a
pasty mixture of the pyrophosphate of soda with quick lime, which mixture is
exposed and stirred on the bottom of a furnace which is in communication
with the hearth; by these means, the soda being set free and divided by the
pyrophosphate that has been formed, is saturated with carbonic acid, arising
from the combustion of the coal.
Second, by passing into the solution of caustic soda, that results from the
action of lime water upon the pyrophosphate, a current of carbonic acid,
which is derived from the ordinary furnace of the works, or else from a furnace
used expressly for that purpose. By using small gasometers it will be easy to
draw in and expel the products arising from the combustion of coal in such
manner as to establish a regular current through the caustic solution, which is
worked in any suitable apparatus, or minutely divided, by being agitated by
means of paddle wheels or agitators. The whole of the foregoing operations
(for soda) may be expressed by the following equations:-
Ph. 0, 2 Ca. O + 2 S0³, aqua = 2 Ca. O, SO3 + Ph. Os, aqua.
Ph. 0, 2 HO+ 2 Na. Cl. Ph. O', 2 Na. O + 2 H Cl.
Ph. O, 2 Na. O + 2 Ca. O = Ph. 0, 2 Ca. O + 2 Na. O.
2 Na. O2 CO2 = 2 Na. O, C 02.
To avoid obtaining, as in the above process, as a residue sulphate of lime,
which is without any value, I have devised the following means of dispensing
entirely with the use and waste of sulphuric acid in making potash and soda.
For this purpose I put together phosphate of lead aud chlorhydric acid,
producing chloride of lead and phosphoric acid. This phosphoric acid, having
been separated from the precipitate, is mixed, evaporated, and calcined with a
suitable quantity of common salt, which yields by distillation chlorhydric acid,

page_text: and a fixed residue, which is pyrophosphate of soda. This pyrophosphate of
soda is dissolved, and then treated with caustic lime until precipitation ceases;
in this way a precipitate of pyrosulphate of lime is formed, besides the solution,
containing caustic soda, which may be carbonated as above set forth. The
phosphate of lime is next boiled with chloride of lead, thus giving chloride of
lime or calcium, and reproducing phosphate of lead, from which the operation
originated. By this process the loss of sulphuric acid is entirely done away
with, and the phosphate of lime, as well as the chlorhydric acid, which are
employed in the process, are being continuously reproduced. The latter process,
in which sulphuric acid is dispensed with, may most advantageously be applied
to extracting potash of soda from the sediments resulting from the evaporation
of salt water at salt works, in marine boilers, &, which sediments are well
known to consist chiefly of chlorides or sulphates of potash, soda, & magnesia.
For this purpose I decompose phosphate of lead as above by means of
chlorhydric acid. This phosphoric acid, being incorporated and calcined with
the waste residue of sea water, gives by distillation a mixture of chlorhydric
and sulphuric acids, leaving as a fixed residue a mixture of phosphates of
potash, of soda, and of magnesia. In fact, either chlorides of sodium, potassium,
and magnesium, or sulphates of soda, potash, and magnesia, when calcined with
phosphoric acid, give, as the case may be, either chlorhydric or sulphuric acids,
and phosphates of potash, soda, and of magnesia. These two acids are purified
by distillation, the latter being much more volatile than the former. To this
fixed residue is added a determinate quantity of caustic alkali, so as to form a
homogeneous paste, which is exposed on the sole of a furnace in communication
with the fire. The mass is stirred with rakes, so as to facilitate the action of
the carbonic acid, and thus the alkali is gradually carbonated, and the mixture
dried and pulverized, so that it may be exposed to carbonic acid from a furnace
in the same manner as lime in gas purifiers; the alkali having been com-
pletely carbonated, the mass, which is a mixture of pyrosulphate of lime and of
magnesia, and of carbonate of potash and soda, which are crystallized one
after the other in due succession. As to the precipitate of phosphate of lime
and of magnesia, it is boiled with chloride of lead, which, by producing
chlorides of calcium and of magnesium, regenerates the phosphate of lead
for the following operations.
By the process above described it will be seen that potash and soda can be
extracted from sea water.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Louis Joseph Frédéric Margueritte in the Great Seal Patent
Office on the 22nd June 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, LOUIS
JOSEPH FRÉDÉRIC MARGUERITTE, Chemist, of Paris, in the Empire of France,
and of 16, Castle Street, Holborn (City), London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of December, in the year of our
Lord One thousand eight hundred and fifty-four, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Louis Joseph Frédéric Margueritte, Her special licence that I, the said
Louis Joseph Frédéric Margueritte, my executors, administrators, and assigns,
or such others as I, the said Louis Joseph Frédéric Margueritte, my execu-
tors, administrators, 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 Channel Islands, and Isle of
Man, an Invention for "IMPROVEMENTS IN THE MANUFACTURE OF CAUSTIC AND
CARBONATED POTASH AND SODA," upon the condition (amongst others) that I, the
said Louis Joseph Frédéric Margueritte, by an instrument in writing under
my hand and seal, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Louis Joseph Frédéric Margueritte, do
hereby declare 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 :-
This Invention consists of an improved means of preparing sulphate of
potash and of soda, and in using phosphoric or pyrophosphoric acid for
manufacturing potash and soda.
As to the first of these processes, viz., for preparing the sulphate of soda or
potash, it will be remembered that the sulphate of soda, for instance, which is
for making glass, and other purposes, is prepared by means of sulphuric acid
and common salt, and this novel process is intended to produce said sulphate
without using lead chambers, and thus avoid the expense attendant upon the
manufacture of sulphuric acid by those means. When common salt is

page_text: calcined with a sulphate, the base of which is capable of forming a volatile
chloride, this chloride may be collected by distillation, and sulphate of soda is
obtained as a fixed residue. Thus, a mixture of sulphate of zinc and chloride
of sodium divides by calcination into sulphate of soda and chloride of zinc,
which is volatilized; also several other sulphates may be used to produce the
same reaction. These results, however, have not been practically applied, as
the manufacture of sulphate of soda by these means necessarily implies the
sulphate used in the calcination to be cheap & abundant, whilst the salts of
that class are generally artificial products or manufacturing waste, and cannot
be applied on account of their high price. On the other hand, sulphuric acid
exists, already formed, in compounds, which are met with in exhaustible
quantities in nature, such as the sulphates of lime and of magnesia, which are
to be found in the dissolved state in sea water, and different springs, plaster of
Paris, sulphates of iron, alumina, &c. The question to resolve then amounts
to rapidly & cheaply producing, by the use of these different sources of
sulphuric acid, some sulphate together with a volatile chloride to be used for
regenerating the sulphate from which it has been obtained, and from the
following description it will be seen that the sulphate and the chloride of lead
fully answer the purposes of these improvements.
To carry out this application of sulphate of lead, I mix chemically equivalent
quantities of said sulphate, which is prepared by roasting galena, or sulphuret
of lead, and of common salt (or of chloride of potassium, if sulphate of
potash is to be obtained), and I subject the mixture to calcination at a strong
and continuous red heat, by which it fuses and becomes quite clear and
transparent. At the surface of the bath thick vapours of chloride of lead
are seen to rise, which evolution will cease as soon as the reaction between
the chloride of sodium and the sulphate of lead is terminated, viz., when the
common salt has been converted into sulphate of soda, and the sulphate of
lead into volatile chloride of lead, which is evolved by calcination. At this
stage of progress the melted mass is run out, and being treated by means of
water, yields crystallized sulphate of soda, and leaves an insoluble residue of
sulphate of lead, which varies in quantity, according to the time during which
the mass has been calcined. This sulphate of lead which has not acted is to
be used in the following operation:-The chloride of lead which has been
condensed is pulverized and held in suspension in a solution of sulphate of
magnesia, or agitated in presence of water with plaster of Paris, or with
sulphate of lime which settles in sea water before salt is made from the same.
In any case the precipitate of chloride of lead is converted into sulphate, giving

page_text: the succeeding operation. These reactions may be expressed by the following
equations:-
Na. Cl.
Pb. Cl.
Pb. OSO³ = Na. OSO³ + Pb. Cl.
MOSO³ = Pb. O SO³ + M Cl.;
in which M O represents the base of any soluble sulphate; since for regene-
rating the sulphate of lead, the chloride of lead may also be made to act
upon sulphate of iron, or of alumina, obtained by the oxydation of aluminous
schists, or upon any soluble sulphate whatever. When the chloride of lead is
digested in water with sulphate of lime, of magnesia, iron, alumina, &c., the
whole of the sulphate is recovered or the regeneration is complete, with the
exception of a very small quantity, that is wasted on account of a small portion
of lead remaining in the liquor that is removed by washing; the smallness of
the quantity of lead remaining is proved by said liquor taking only a slight
brown tinge upon some hydrosulphate of ammonia being added.. In the
digesting process rather dilute solutions have to be used, for if sulphate of lead
be put into contact with a concentrated solution of chloride of potassium,
sodium, magnesium, or of calcium, the solution being filtered and treated with
an alkaline sulphuret, yields an abundant precipitate of sulphuret of lead;
whence it follows that the sulphate of lead, by way of double decomposition, is
converted by either of said chlorides into a soluble chloride of lead, which,
however, only takes place when the solution is concentrated. Hence, if the
transformation of the chloride of lead into sulphate were operated in concen-
trated liquors by means of sulphate of lime, a solution of chloride of calcium
would be produced, that would retain & waste a considerable quantity of
chloride of lead. For this reason sea water cannot be employed in its natural
state for that purpose, since the considerable quantity of chloride of sodium and
of magnesium which it contains dissolves a proportionate quantity of lead,
and this is avoided by diluting the sea water suitably, and adding sulphate
of lime.
The regeneration of the sulphate of lead forms the principal feature of this
process, constituting the base and economy, as it were, of the same. The
arrangement of the apparatus to be used for said process may be devised in
various ways, keeping in view, however, the two following requirements:-
First, the furnace bottom upon which the calcination of the mixture is carried
on should have as large a surface and as little depth as possible, for the
purpose of facilitating the volatilization of the chloride of lead; second, the

page_text: vault of the furnace should be rather low, so that the current of air carrying
off the vapours of chloride of lead from the surface may be rapid & strong,
and not have much volume, so as to cool the melted mass.
The furnace may,
for instance, resemble a low gas retort open at both ends, the lower sole of
which is hollowed out some inches deep so as to contain the fused mass. At
one end there is an open door, through which the air is made to enter in any
suitable proportion, and at the other end there is a condensing apparatus that
is in communication with a draught chimney, the object of these contrivances
being to create a continuous current of air in the retort for conveying the
vapours of chloride of lead into the condensing apparatus, where they are
stopped. Instead of air, a current of steam may sometimes be used to
advantage, as the mixture will thus be protected against the action of the air,
and the steam carries off the chloride vapours, and condenses along with them
very satisfactorily. The condenser is constructed like those already known,
and therefore need not be described in particular; but it should have a very
great number of surfaces, that may be used in the dry state, or can be
moistened by a jet of water or of steam, and these surfaces should be so
constructed as to facilitate collecting the condensed chloride of lead. By
employing retorts, the furnace would have to be similar to those used in the
manufacture of gas, and might contain five or more retorts. The mixture of
sulphate of lead and of chloride of sodium is introduced into the retorts by
means of a shovel or of a scoop, and the liquid mass being contained upon an
incline, is discharged through an opening at the entrance of the retort, which
is kept closed with loam or clay to the end of the operation. Both on account
of their solidity and when great quantities have to be treated at once, regular
furnaces may be preferable to retorts; but whatever may be the kind of
apparatus used for calcining and condensing, their construction will be so
simple as to render any further description of them useless. In conclusion,
the process for preparing sulphates of soda and potash which I have herein-
before set forth consists in calcining sulphate of lead with chloride of sodium
or of potassium, and bringing the chloride of lead so produced into contact
with sulphate of lime, or any other soluble sulphate capable of regenerating
the sulphate of lead. This continuous method of producing sulphates of soda
and of potash without free sulphuric acid, and hence without lead chambers,
appears to offer considerable advantages over the modes hitherto practised, and
is a decided improvement upon Leblanc's process of manufacturing soda &
potash. These improvements also relate, as stated at the outset, to two pro-
cesses for using phosphoric or pyrophosphoric acid in the manufacture of

page_text: soda and potash, either by preparing pyrophosphate of soda and of potash, or
by employing in the free state phosphoric acid that has been obtained by the
wet process.
The preparation of pyrophosphate of soda or potash, which constitutes the
second improved process, is in every respect analogous to that of sulphate of
soda or potash, previously described, and is effected by calcining, in apparatus
similar to those above described, pyrophosphate of lead (2 Pb. O), Ph. O, or of
zinc, 2 (ZnO) Ph. O³, with a determinate quantity of chloride of sodium or
potassium. Vapours of chloride of lead or of zinc will thus be seen to rise
abundantly, and may be carried off by a current of air or steam, and collected
by condensation. The melted mass is treated with water, which dissolves the
alkaline pyrophosphate, and leaves as an insoluble residue metallic pyrophos-
phate, which is used in the succeeding operation. The solution of alkaline
pyrophosphate is treated with quick lime, which gives a precipitate of pyro-
phosphate of lime, and the soda or potash is removed in the caustic state. The
liquor thus obtained may at once be used by soap boilers, or be converted into
carbonate by a current of carbonic acid gas, as may be desired. The preci-
pitate of pyrophosphate of lime is diluted with water, and mixed hot or cold
with sublimate of chloride of lead or zinc, whereby I obtain pyrophosphate of
lead or of zinc and chloride of calcium, which may be got rid of by washing.
The pyrophosphate of lead or zinc, which forms the base of the operation, is
thus regenerated. In calcining pyrophosphate of lead or of zinc with chloride
of sodium, the insoluble residue is larger than in the same operation with
sulphate of lead, which may be explained by the pyrophosphate of soda being
less fusible than the sulphate, and consequently the mass being more viscous
and less apt to mix on being stirred, and thus facilitate evaporation. This pre-
paration of pyrophosphate of soda evidently amounts to a calcining process,
and yields the caustic alkali directly by the mere addition of lime, and, like the
preceding process herein-before described, it does away with the use of sul-
phuric acid, and also with the calcination, which in Leblanc's process is
practised upon sulphate of soda, chalk, and coal, for obtaining raw carbonated
soda. It may also be observed here, that instead of pyrophosphate of lead or
of zinc, metaphosphate of the same bases may be used, thus producing meta-
phosphate of alkali & caustic alkali by the process described above for the
The chemical equivalent of zinc being much lighter than that of
lead, phosphates of zinc will be found more economical to use than phosphates
of lead.
like case.
As to the third process, which consists in using phosphoric acid in the

page_text: free state, I prepare in the following manner phosphate of soda, from which
caustic soda is immediately obtained, as has been shewn above:-I treat, with
a suitable quantity of sulphuric acid, phosphate of lime, which may be obtained
by calcination of bones, by precipitating urinous matters or gelatinous water
by lime, or in any other suitable way, and I thus obtain a precipitate of
sulphate of lime and of free phosphoric acid, and a certain quantity of lime is
held in solution. The phosphoric acid liquor having been separated from the
precipitate, is mixed with a determinate quantity of common salt, or else chlo-
ride of potassium, if potash is to be obtained. This mixture is then evaporated
and calcined in apparatus that are analogous to those commonly used in
making sulphate of soda. The chlorhydric acid resulting from this operation
is collected, and the calcined residue, which consists of phosphate, or rather
pyrophosphate of soda, is treated with water. To this solution is added lime
water until precipitation ceases, that is to say, until all the phosphoric acid be
eliminated in the shape of phosphate of lime, whose composition is Ph. O³,
2 Ca. O, taking thus care to avoid any excess of lime, lest its further decompo-
sition of the phosphate should involve a useless expenditure of sulphuric acid,
since the phosphate of lime, which forms the base of the operation, is to be
reproduced indefinitely. The liquor which supernatates above the precipitate
is a solution of caustic soda, which without any further preparation may
directly be used for soap making. For preparing this caustic soda for sale, it
must evaporated in the usual vessels & with the usual precautions until it
is solidified. As it may, however, be desirable to obtain the soda in the car-
bonated state, in which it is consumed in large quantities, it may be useful to
set forth different ways in which it may be obtained; viz., first, by forming a
pasty mixture of the pyrophosphate of soda with quick lime, which mixture
exposed and stirred on the bottom of a furnace which is in communication
with the fire-place; by these means, the caustic soda being set free, and
divided by the pyrophosphate that has been formed, is saturated with carbonic
acid, arising from the combustion of the coal. Second, by passing into the
solution of caustic soda, that is obtained by the action of lime water upon
the pyrophosphate, a current of carbonic acid, which is derived from the
ordinary furnace of the works, or else from a furnace built expressly for that
purpose. By using a set of small gasometers it will be easy to draw in and
expel the products arising from the combustion of coal, in such manner as to
establish a regular current through the caustic solution, which may be placed
in a Woolf's apparatus, or minutely divided, by being constantly agitated by
means of paddle wheels. By either of these two modes the alkali is completely

page_text: saturated with carbonic acid, since mere exposure to atmospheric air would
produce the same result. Practice alone will shew which of the two modes is
to be adopted in preference.
The whole of the foregoing operations may be expressed for soda by the
following equations:-
Ph. 0%, 2 Ca. O +2 S0³, aqua = 2 Ca. OSO³ + Ph. O³, aqua.
Ph. O, 2 HO+ 2 Na. Cl. = Ph. O', 2 Na. O +2 H. Cl.
Ph. O, 2 Na. O + 2 Ca. O = Ph. 0%, 2 Ca. O + 2 Na. O.
2 Na. O2 CO2 Na. OCO².
For
soap making, the use of phosphoric acid in the manufacture of soda
has the advantage of producing at once the alkaline liquor required, thus
avoiding the imperfection and waste attending upon the use of commercial
soda, manufactured in the usual way.
To avoid getting as a residue in the above process sulphate of lime, which
is without any value, I have devised the following means of dispensing entirely
with the use and waste of sulphuric acid in making potash & soda. For
this purpose, I put together phosphate of lead and chlorhydric acid, thus pro-
ducing chloride of lead and phosphoric acid. The latter, having been separated
from the precipitate, is mixed, evaporated, and calcined with a considerable
quantity of common salt, which yields by distillation chlorhydric acid, and a
fixed residue, viz., pyrophosphate of soda. This pyrophosphate of soda is dis-
solved, and then treated with caustic lime, until precipitation ceases. In this
way a precipitate of pyrophosphate of lime is formed, besides the solution
containing caustic soda, which may be carbonated with carbonic acid. The
phosphate of lime is next boiled with chloride of lead, thus giving chloride of
calcium, and reproducing the phosphate of lead, from which the operation
originated. These different reactions are represented by the following equa-
tions:-
.
Ph. O, 2 Pb. O + 2 II Cl., aqua
Ph. O, 2 HO+ 2 Na. Cl. =
Ph. O, 2 Na. O + 2 Ca. O =
2 Pb. Cl + Ph. O', aqua.
Ph. O, 2 Na. O + 2 II Cl.
Ph. O, 2 Ca. O + 2 Na. O.
Ph. O, 2 Ca. O + 2 Pb. Cl. = 2 Ca. Cl. + Ph. 0, 2 Pb. O.
By this process, as will be seen, the expenditure of sulphuric acid is entirely
dispensed with, and the phosphate of lead, as well as the chlorhydric acid,
which form the instruments, as it were, of the operation, are being continuously
reproduced.
The process last described may most advantageously be applied to extracting
soda and potash from the sediments resulting from the evaporation of salt

page_text: water at salt works, ponds, or lakes, in marine boilers, &c., which sediments
are well known to consist chiefly of salts of potash, soda, or magnesia that
are in the state of chlorides or sulphates. For this purpose I decompose
phosphate of lead, as above set forth, by means of chlorhydric acid. The
phosphoric acid being evaporated and calcined with the waste residue of sea
water, gives by distillation a mixture of chlorhydric and sulphuric acid, leaving
as a fixed residue a mixture of phosphates of potash, soda, & magnesia.
In fact, either chlorides of sodium, potassium, and magnesium, or sulphates
of soda, potash, and magnesia, when calcined with phosphoric acid, give, as
the case may be, either chlorhydric or sulphuric acid, and phosphate of soda,
potash, and of magnesia. These two acids are purified by distillation, the
chlorhydric acid being much more volatile than the other. To the fixed
residue, which consists of phosphate of soda, potash, and magnesia, I add a
determinate quantity of caustic lime, so as to form a homogeneous paste,
which is exposed upon the soles or bottoms of furnaces which are in com-
munication with the fire. The mass is stirred with iron rakes, so as to
facilitate the action of the carbonic acid, by frequently changing the surface
acted upon, and thus the alkali is gradually carbonated, and the mixture dried
and pulverized, so that it might, if required, be exposed to carbonic acid from
furnaces, in the same manner as lime in gas purifiers, through which a current
of carbonic acid gas taken at the fire-place might be sent by means of a suit-
able contrivance of gasometers. The mixture of pyrophosphate of soda and
diluted lime may be dried and brought to the pulverulent state without
depriving the soda of its state of liberty. The alkali, having been completely
carbonated, is extracted by lixiviating the mass, which is a mixture of pyro-
phosphate of lime, of magnesia, and of carbonate of potash and of soda, which
are crystallized one after the other in due succession. As to the precipitate
of phosphate of lime and of magnesia, it is boiled with chloride of lead, which,
by producing chlorides of calcium & of magnesium, regenerates the phos-
phate of lead for the succeeding operation. By this process, then, the soda
and potash contained in sea water may be extracted.
The operations relating thereto are expressed by the following equations:-
Ph. O, 2 Pb. O + 2 H Cl. aqua = 2 Pb. Cl. + Ph. 0³, aqua.
Ph. 0, 2 HOM. Cl. + Mg. 0³
SO³, aqua.
-
Ph. O, MO. Mg. O + 2 H Cl. +
Ph. O', MO. Mg. O + Ca. O. = Ph. Os, Ca. O. Mg. O + MO. (caustic.)
Ph 0 C 0 M o O, OP₁ CL — Ph 05 9 Pb 0 + Co Cl MC

page_text: Having thus fully described the nature of my Invention, and the manner in
which the same is or may be carried into effect, I wish it to be distinctly
understood, that without confining myself to the precise details above stated,
what I claim as novel, & therefore being secured to me by the herein-before
recited Letters Patent, is,-
First, the method of preparing sulphate of potash & of soda in a con-
tinuous manner, and without free sulphuric acid, by calcining sulphate of lead
with chlorides of potassium & of sodium, & by regenerating the sulphate
of lead.
Second, the method of preparing in a continuous manner pyrophosphates
& metaphosphates of potash & of soda, either by calcining pyrophosphate
and metaphosphate of lead and of zinc with the chlorides of potassium and
of sodium, or by decomposing phosphate of lime by sulphuric acid, and also
phosphate of lead by chlorhydric acid; and also the method of regenerating
pyrophosphate & metaphosphate of lead and of zinc by means of pyro-
phosphate & metaphosphate of lime and chloride of lead and of zinc.
Third, preparing caustic potash and soda, by merely adding lime to the
pyrophosphate of potash or of soda.
In witness whereof, I, the said Louis Joseph Frédéric Margueritte,
have hereunto set my hand & seal, this Eighteenth day of June, One
thousand eight hundred and fifty-five.
FREDERIC MARGUERITIE. (L.S.)