IMPROVEMENTS IN THE MANU- FACTURE OF SULPHURIC ACID
Year: 1854

page_text: 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 SULPHURIC ACID" to be as follows, viz.:-
These improvements consist in extracting sulphuric acid from plaster of Paris,
or sulphate of lime and other natural sulphates, by means of phosphoric acid;
this extraction is founded upon the fact of sulphate of potash, soda, magneisa,
barytes, and, latterly, also sulphate of lime, being decomposed by being
calcined together with phosphoric acid.
The manner in which I proceed for sulphate of lime is as follows:-I

page_text: take phosphate of lead, which is easily produced by boiling phosphate of
lime with chloride of lead; this phosphate of lead is then decomposed by
chlorhydric acid, thus producing chloride of lead and setting the phosphoric
acid at liberty. The phosphoric acid thus obtained is mixed, evaporated, and
calcined with a determinate quantity of sulphate of lime, and sulphuric acid
is thus obtained by distillation, besides phosphate of lime remaining as a fixed
residue. This latter is boiled with chloride of lead. obtained before, thus
producing phosphate of lead and chloride of calcium; the phosphate of lead,
which is the basis of the operation, is being reproduced indefinitely, but the
chlorhydric acid is converted with chloride of calcium. The whole operation
may be represented by the following equations:-
Ph. O, 2 Pb. O + 2 H. Cl., aqua = 2 Pb. Cl. + Ph. O³, aqua;
Ph. O, aqua +2 Ca. OSO = Ph. O'; 2 Ca. O + 2 SO³, aqua;
Ph. O, 2 Ca. O + 2 Pb. Cl. = 2 Ca. Cl. + Ph. O', 2 Pb. O.
Since in the manufacture of soda, by decomposing common salt by means of
sulphuric acid, an equivalent quantity of chlorhydric acid is obtained, this
acid may be usefully employed in the above-described way for generating the
sulphuric acid used in said manufacture.
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 exe-
cutors, 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

page_text: the United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for "IMPROVEMENTS IN THE MANUFACTURE OF
SULPHURIC ACID," 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 Frederic Margueritte, do
hereby declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement:-
These improvements consist in extracting sulphuric acid from plaster of
Paris, or sulphate of lime and other natural sulphates, by means of phosphoric
acid. In a Patent which I have taken out for "Improvements in the
Manufacture of Caustic and Carbonated Potash and Soda," bearing the same
date as the present Letters Patent, and numbered 2701, I have shewn that
the sulphates of soda and of magnesia are decomposed by being calcined with
phosphoric acid, thus producing sulphuric acid by distillation. The present
novel mode of extracting sulphuric acid is founded upon the same kind of
process which applies equally to sulphate of lime, of barytes, &c., and com-
prizes also a means of extracting sulphuric acid by means of chlorhydric acid.
The manner in which I proceed for sulphate of lime is as follows:-I take
phosphate of lead, which is easily procured by boiling phosphate of lime with
chloride of lead; this phosphate of lead is then decomposed by means of
chlorhydric acid, thus producing chloride of lead and setting the phosphoric
acid at liberty. The phosphoric acid thus obtained having been separated
from the precipitate, is mixed, evaporated, and calcined with a determinate
quantity of plaster of Paris or sulphate of lime, and sulphuric acid is thus
obtained by distillation, besides phosphate of lime remaining as a fixed residue.
This latter is boiled with chloride of lead previously obtained, thus producing
phosphate of lead and chloride of calcium; the phosphate of lead, which forms
the base of the operation, is being reproduced indefinitely, but the chlorhydric
acid is lost in the shape of chloride of calcium, this loss constituting the whole
expenditure involved in the process, which in fact consists in exchanging
chlorhydric acid for sulphuric acid; and it will be observed, that this exchange
may be made use of by soda makers for recovering the sulphuric acid employed
in the ordinary mode of manufacture; in other words, since by decomposing

page_text: common salt by sulphuric acid a chemically equivalent quantity of chlorhydric
acid is obtained, it will be easy to regenerate by the process just described
almost the entire quantity of sulphuric acid that is required. The whole
of the operations above described may be represented by the following
equations:-
Ph. 0, 2 Pb. O + 2 H. Cl., aqua = 2 Pb. Cl. + Ph. '05, aqua;
Ph. O, aqua +2 Ca. OSO³ Ph. O, 2 Ca. O + 2 SO³, aqua;
Ph. O, 2 Ca. O +2 Pb. Cl. = 2 Ca. Cl. + Ph. O³, 2 Pb. O;
and by this process about 72 lbs. of monohydrated sulphuric acid may
be obtained from 100 lbs. burnt or anhydrous plaster, and 56,7 lbs. mono-
hydrated or commercial acid from 100 lbs. hydrated plaster or gypsum. The
sulphuric acid may also be obtained by the same process from other natural
sulphates, such as sulphates of soda, magnesia, barytes, and other bases. The
extraction of sulphuric acid from plaster need not necessarily depend of, or
be carried on in connexion with, the manufacture of soda, which yields the
chlorhydric acid used for the reaction, since large quantities of chlorhydric
acid may be obtained from the calcination of the chloride of magnesia, as left
by the evaporation of salt waters. I would also observe here, that by mixing
chloride of magnesia with clay or argil it may be almost completely decom-
posed by calcination, and made to yield the greater portion of the chlorhydric
acid contained in it, the argil acting in this case by supplying water at a
high temperature, thus materially aiding the decomposition of the chloride of
magnesia.
Sulphuric acid may also be directly extracted from sulphate of soda, potash,
and lead by means of chlorhydric acid, and for this purpose the following
modus operandi may be adopted :-A current of chlorhydric acid gas is made
to pass as long as it will be received into a saturated solution of sulphate of
potash or of soda which contains crystals of those salts; by these means
chloride of potassium or of sodium is obtained, and free sulphuric acid is left
in the solution; this latter being distilled gives first chlorhydric acid, which
is collected in a solution of sulphate of potash or of soda, and next sulphuric
acid, which is easily purified by distillation.
With sulphate of lead sulphuric acid is obtained in the following manner :-
Sulphate of lead is boiled with chlorhydric acid, the sulphate thus being con-
verted into chloride of lead, and leaving its sulphuric acid in the solution, from
which it is obtained by distillation, as before.
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

page_text: understood that I do not limit myself to the precise details given above; but
what I claim as the novel principles involved in this Invention is,-
First, applying the action of phosphoric acid upon sulphate of lime, barytes,
magnesia, and similar bases to the manufacture of sulphuric acid.
Second, applying the action of chlorhydric acid upon sulphate of soda,
potash, or lead to the manufacture of sulphuric acid, substantially as above
described.
In witness whereof, I, the said Louis Joseph Frédéric Margueritte, have
hereunto set my hand and seal, this Eighteenth day of June, One
thousand eight hundred and fifty-five.
FRÉDÉRIC MARGUERITTE. (L.S.)