IMPROVEMENTS IN THE MANUFACTURE OF SUPERPHOSPHATE OF LIME
Year: 1869

page_text: LETTERS PATENT to Alexander Melville Clark, of .53, Chancery
Lane, in the County of Middlesex, Patent Agent, for the Invention
of IMPROVEMENTS IN THE MANUFACTURE OF SUPERPHOSPHATE OF LIME."-A
communication from abroad by Lucien Henri Blanchard, Merchant
of 13, Boulevart St. Martin, Paris.
Sealed the 3rd June 1870. and dated the 16th December 1869.
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 16th December 1869.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF SUPER-
PHOSPHATE OP LIME," to be as follows:--
In the manufacture of superphosphate, as ordinarily practised, the
tribasic phosphates of lime obtained from bones, coprolites, and apatites
are first reduced to powder and then treated with a certain quantity of
sulphuric acid, the resulting product being in powder. If, however, this

page_text: action be complete, that is to say, if the amount of sulphuric acid be
such as is theoretically requisite to absorb the whole of the lime in order
to render the phosphoric acid soluble, the product obtained, viz., the
superphosphate, would consist of a fatty body unsuitable for the purpose
desired, and requiring to be mixed (in order to render it available) with
other matters, which lessen its concentration to a proportionate extent.
Ordinarily a small quantity of sulphuric acid is employed, sufficient only
to obtain a product in the form of powder. As a consequence of this a
part only of the tribasic phosphate of lime is acted on, and hence but
a part only of the phosphoric acid is rendered soluble.
Thus super-
phosphates as now produced always contain a proportion of soluble
phosphates and a considerable proportion of insoluble phosphate.
The above mode of manufacture is thus imperfect, inasmuch as a large
proportion of the richness of the phosphate remains unproductive in the
form of insoluble phosphate, owing to the small degree of concentration
of the superphosphate.
The improvements of this Invention have for their object,-
Jst. To render soluble the whole of the phosphoric acid.
2ndly. To obtain fram said phosphoric acid products consisting of
superphosphates in a pulverized condition and highly concentrated, even
although the phosphates treated be of but medium quality. For this
purpose I treat the phosphates of lime in powder in a large container
lined with lead, adding from three to four parts of water. I then add
the amount of sulphuric acid proportionate to the richness of the
phosphate under treatment, and mix the whole sufficiently to render
the action of the acid as perfect as possible. In this manner I obtain
liquors, which I first concentrate to about 25 degrees Beaumé, and then
by adding one-tenth of the sulphuric acid previously employed I pre-
cipitate the lime and consequently obtain liquid phosphoric acid, which
I then proceed to concentrate to about 50 degrees Beaumé. This being
done I take the residue of the above operation after having dried it as
perfectly as possible, while preserving its quality as a sulphate of lime,
and mix it with as much as possible of the phosphoric acid at 50 degrees
Beaumé previously obtained, the supply being cut off when the product
ceases to form a powder or is sufficiently dried. In the above manner
I am enabled to obtain superphosphates of an exceptionally rich nature
and of uniform quality; for example, I obtain a product containing from

page_text: 18 to 19 per cent. of soluble phosphoric acid, which exceeds by 50 per
cent. the degree of concentration of ordinary superphosphates.
The improved mode of manufacture of this Invention instead of being
comprised in a single operation, viz., by the action of sulphuric acid on
the phosphates, consists of two operations, viz.,-
1st. The treatment of the phosphate and the subsequent separation of
the phosphoric acid obtained in a free state.
2ndly. The mixing of the concentrated phosphoric acid with the
sulphated residues of lime resulting from the primary operation.
The results I obtain are as follows:-There is not any portion of the
phosphates remaining unproductive; I obtain a very high degree of
concentration with a mathematical exactness; and, lastly, for the above
purposes I may use phosphates of either rich or medium quality alike.
I reserve the right of mixing the phosphoric acid with the residues of
sulphate of lime in any form I may find most suitable.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark in the Great Seal Patent
Office on the 11th June 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixteenth day of December, in the
year of our Lord One thousand eight hundred and sixty-nine, in the
thirty-third year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Alexander Melville Clark,
Her special licence that I, the said Alexander Melville Clark, my
executors, administrators, and assigns, or such others as I, the said
Alexander Melville Clark, my executors, 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 SUPER-
.

page_text: PHOSPHATE OF LIME," a communication to me from abroad by Lucien Henri
Blanchard, Merchant, of 13, Boulevart St. Martin, Paris, upon the
condition (amongst others) that I, the said Alexander Melville Clark,
my executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, 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 Alexander Melville Clark, 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, that is to say:-
The manufacture of superphosphate as ordinarily practised consists
in treating the tribasic phosphates of lime from bones, coprolites, and
apatites, which are first reduced to powder, with a certain quantity of
sulphuric acid, the resulting product being in powder. If, however, this
action be complete, that is to say, if the amount of sulphuric acid be
such as is theoretically requisite to abstract the whole of the lime in
order to yield soluble phosphoric acid, the product obtained, viz., the
superphosphate, would consist of a fatty body unsuitable for the purpose
desired, and requiring to be mixed (in order to render it available) with
other matters, which lessen its concentration to a proportionate extent.
Ordinarily such a small quantity of sulphuric acid is employed as will
leave the product in the form of powder, in consequence of which a
part only of the tribasic phosphate of lime is acted on, and hence but
a part only of the phosphoric acid is rendered soluble. Thus super-
phosphates as now produced always contain a proportion of soluble
phosphates and a considerable proportion of insoluble phosphates.
The above mode of manufacture is thus imperfect, inasmuch as a
large proportion of the richness of the phosphate treated remains
unproductive in the form of insoluble phosphate, and also from the
low degree of concentration of the superphosphate.
The improvements of this Invention have for their object,―
1st. To render soluble the whole of the phosphoric acid.
2ndly. To obtain from said phosphoric acid products consisting of
superphosphate in a pulverized and highly concentrated condition,

page_text: even although the phosphates treated be of but medium quality. For
this purpose I treat the phosphates of lime in powder in a large con-
tainer lined with lead, adding from three to four parts of water. I then
add the amount of sulphuric acid proportionate to the richness of the
phosphate under treatment, and mix the whole sufficiently to render
the action of the acid as perfect as possible. In this manner after
filtering and washing I obtain liquors which I first concentrate to about
25 degrees Beaumé, and then by adding one-tenth of the quantity of sul-
phuric acid previously employed I precipitate the lime, and consequently
obtain liquid phosphoric acid, which I then proceed to concentrate to
about 50 degrees Beaumé. This being done I take the residue of the
above operation after having dried it as perfectly as possible while
preserving its quality as a sulphate of lime, and mix it with as much
as possible of the phosphoric acid at 50 degrees Beaumé previously
obtained, the supply of the latter being, however, determined when the
product would no longer form a powder or be sufficiently dry. In the
above manner I am enabled to obtain superphosphates of an excep-
tionally rich nature and of uniform quality; for example, I obtain a
product containing from 18 to 19 per cent. of soluble phosphoric acid,
which exceeds by 50 per cent. the average degree of concentration of
ordinary superphosphates. I may also after having obtained the phos-
phoric acid by elimination, partly in the form of acid phosphate of
lime and partly in the form of phosphoric acid, transform the whole into
acid phosphate of lime by adding a solution of lime thereto. I then
evaporate this acid phosphate of lime until it contains the consistency of
treacle, and dry it completely by the addition of a quantity of quick-
lime, varying from one-fifth to one-tenth by weight of the acid phosphate
under treatment. In the above manner I obtain a highly concentrated
product containing as much as from 55 to 56 per cent. of anhydrous
phosphoric acid in a pulverulent condition and constituting a super-
phosphate of considerable richness.
The improved mode of manufacture of this Invention instead of being
comprised. in a single operation, viz., by the action of sulphuric acid
on the phosphates, consists of two operatious, viz.,-
1st. The treatment of the phosphate and the subsequent separation
in a free' state of the phosphoric acid obtained.
2ndly. The mixing of the concentrated phosphoric acid with the
sulphate of lime resulting from the primary operation.

page_text: The results I obtain by the first operation are as follows :-I do not
leave improductive any portion of the phosphates treated; I obtain a
very high degree of concentration, which may moreover be effected
with mathematical regularity; and, lastly, I may use phosphates of
either rich or medium quality with equal effect.
By the second operation I also obtain a more highly concentrated
product, but still of a uniform quality, while I may use alike either
rich or inferior phosphates. I may also after extracting a portion of
the phosphoric acid from the magma convert the residues into blocks
or cakes containing a considerable proportion of soluble phosphoric
acid. These moulded blocks may be readily stored under shelter, but
open to the action of the air for the purpose of drying the same, and in
this form they may be readily transported from place to place. When
required for use the blocks may be ground or reduced to a state of
powder, and soluble phosphoric acid then added by sprinkling or
otherwise for the purpose of more highly concentrating the products.
Having described the nature of the Invention, and the manner of
performing the same, I declare that what I claim as the Invention to
be protected by the herein-before in part recited Letters Patent is, the
manufacture of superphosphate of lime by two operations in the manner
herein-before described while reserving the right to mix the phosphoric
acid with the residuary sulphates of lime in any convenient condition.
In witness whereof, I, the said Alexander Melville Clark, have here-
unto set my hand and seal, this Eleventh day of June, in the
year of our Lord One thousand eight hundred and seventy.
Witness,
W. G. A. SWINNOCK,
53, Chancery Lane,
London.
A. M. CLARK.
(L.S.)