AN IMPROVED MODE OF OBTAINING PYROPHOSPHATE OF LIME
Year: 1869

page_text: LETTERS PATENT to Michael Henry, of 68, Fleet Street, in the City
of London, Patent Agent, for the Invention of "AN IMPROVED MODE
OF OBTAINING PYROPHOSPHATE OF LIME."-A communication from
abroad by Ernest Deligny, of 17, Boulevard Saint Martin, Paris,
France.
Sealed the 9th October 1869, and dated the 21st April 1869.
PROVISIONAL SPECIFICATION left by the said Michael Henry at the
Office of the Commissioners of Patents, with his Petition, on the
21st April 1869.
I, MICHAEL HENRY, of 68, Fleet Street, in the City of London,
Patent Agent, do hereby declare the nature of the said Invention for
"AN IMPROVED MODE OF OBTAINING PYROPHOSPHATE OF LIME," (communicated
to me from abroad by Ernest Deligny, of 17, Boulevard Saint Martin,
Paris, France,) to be as follows:-
When hydrochloric or chlorohydric acid acts on phosphate of lime
more or less mixed with carbonates, fluorides, or other matters a solution
is obtained containing acid phosphate of lime and chloride of calcium.

page_text: Hitherto to utilize this compound after decanting and separating the
insoluble gangues the acid phosphate has been precipitated by lime and
washed, and tribasic phosphate obtained. This phosphate is rendered
assimilable by sulphuric action, which converts it into a compound of
acid phosphate and sulphate of lime. Thus the chloride of calcium has
been eliminated.
Phosphoric acid when displaced or replaced in a cold state by certain
acids in solution will itself displace or replace these same acids when the
solution has attained a temperature of 90° to 100° centigrade. When
dessicated under heat the operation becomes more complete.
Now according to this Invention this reaction is applied to a solution
containing chloride of calcium and acid phosphate of lime. The solution
is evaporated to dryness, and a dry product is obtained, which taken after
washing yields a nearly insoluble phosphate of lime and chloride of
calcium. The hydrochloric acid liberated by the operation is collected
and concentrated to serve again. Thus a bibasic phosphate or pyro-
phosphate of lime is obtained (Ph O³ 2 CaO) without equivalent of
water. The importance of the process specially consists in the employ-
ment of hydrochloric acid.
The process may be described as consisting in applying the reaction,
whereby at a suitable temperature phosphoric acid combined with
lime in a state of acid phosphate decomposes chloride of calcium,
setting free hydrochloric acid and absorbing the equivalent of lime
disengaged.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Michael Henry in the Great Seal Patent Office on
the 21st October 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MICHAEL
HENRY, of 68, Fleet Street, in the City of London, Patent Agent, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-first day of April, in the year of
our Lord One thousand eight hundred and sixty-nine, in the thirty-second
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Michael Henry, Her special licence that I, the

page_text: said Michael Henry, my executors, administrators, and assigns, or such
others as I, the said Michael Henry, 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 "AN IMPROVED MODE OF OBTAINING
PYROPHOSPHATE OF LIME," communicated to me from abroad by Ernest
Deligny, of 17, Boulevard Saint Martin, Paris, France, upon the
condition (amongst others) that I, the said Michael Henry, 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 Michael Henry, 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 thereof, as communicated to me, that is to say :-
When hydrochloric or chlorohydric acid acts on phosphate of lime
more or less mixed with carbonates, fluorides, or other matters a solution.
is obtained containing acid phosphate of lime and chloride of calcium.
Hitherto to utilize this compound after decanting and separating the
insoluble gangues the acid phosphate has been precipitated by lime and
washed and tribasic phosphate obtained. This phosphate is rendered
assimilable by sulphuric action, which converts it into a compound of
acid phosphate and sulphate of lime. Thus the chloride of calcium has
been climinated.
Phosphoric acid when displaced or replaced in a cold state by certain
acids in solution will itself displace or replace these same acids when the
solution has attained a temperatute of 90° to 100° centigrade (say 194°
to 212° Fahrenheit). When desiccated under heat the operation
becomes more complete.
Now according to this Invention this reaction is applied to a solution
containing chloride of calcium and acid phosphate of lime. The solution
is evaporated to dryness and a dry product is obtained, which, when
taken after washing, yields a nearly insoluble phosphate of lime and

page_text: chloride of calcium. The hydrochloric acid liberated by the operation
is collected and concentrated to serve again. Thus a bibasic phosphate
or pyrophosphate of lime is obtained, Ph O³ 2 Ca O, without equivalent of
water. The importance of the process especially consists in the above-
described employment of hydrochloric acid.
The process may be described as consisting in applying the reaction
whereby at a suitable temperature phosphoric acid combined with lime in
a state of acid phosphate decomposes chloride of calcium, setting free
hydrochloric acid and absorbing the equivalent of lime disengaged.
I now proceed more particularly to describe the nature of the Invention
and the mode in which it is carried into practical effect.
The Inventor states that when seeking means of rendering natural
phosphates of lime assimilable he discovered a reaction hitherto unknown,
which may be applied for obtaining and treating marketable products.
The reaction may be thus explained:-When a phosphate of lime,
whether of animal or mineral origin, and whether more or less mixed
with carbonates, fluorides, or other extraneous matters is subjected to
the action of hydrochloric or chlorohydric acid a solution is obtained
containing acid phosphate of lime, Ph Os Ca O, and chloride of calcium.
Hitherto when it has been thought desirable to utilize this compound,
then after decanting and separating the insoluble gangues the acid
phosphate has been precipitated by lime and washed, whereupon tribasic
phosphate will be again obtained in a more or less pure condition. This
phosphate is rendered assimilable by means of sulphuric action, which
converts into a mixture of acid phosphate and sulphate of lime. By
these means chloride of calcium will have been eliminated. The chloride
of calcium when in excess is prejudicial to vegetation, and its deliquesence
is detrimental to the preservation of dry powdered manure.
When experimenting upon phosphates or phosphoric acid the
Inventor observed that phosphoric acid when displaced or replaced in a
cold condition by certain acids in a state of solution will itself displace
those acids when the solution shall have reached a temperature of from
When desiccated or
90° to 100° centigrade, say 194° to 212° Fahrenheit.
thoroughly dried by means of heat the operation becomes more
completely effected.
Now according to this Invention this reaction which has not hitherto
been known or utilized is applied to the solution containing chloride of

page_text: calcium and acid phosphate of lime. This solution is evaporated to
dryness in a drying chamber or oven such as is used when drying
sulphate of soda. By these means a dry product is obtained, which after
washing yields on the one hand a nearly insoluble phosphate of lime, and
on the other hand it yields chloride of calcium. The hydrochloric acid
which is liberated by the operation may be collected and treated in an
ordinary concentrating tower or concentrating apparatus, so that it may
serve again. The phosphate of lime obtained is not a tribasic phos-
phate (Ph O 3 Ca O), as was produced by ordinary precipitation by lime,
but a bibasic phosphate (Ph O'2 Ca O) without any equivalent of water,
that is to say, a pyrophosphate. This product contains, say, 55 per cent.
of phosphoric acid, and it may be obtained easily and regularly, and
without any difficulty of manipulation.
The essential feature of the process may thus be described as consisting
in the employment of a chemical agent, that is to say, hydrochloric acid,
for the production of an important marketable product in the manner
described and for the purpose stated.
This utilization of hydrochloric acid is especially advantageous in
manufactories of soda, as it affords means of utilizing a hitherto trouble-
some product.
The operation may be conducted in ordinary decomposition furnaces or
apparatus used in the manufacture of soda. A muriatic solution at a
density of 30° or 35° Baumé is poured into the decomposing vat and
evaporated until it acquires a pasty condition, when it is subjected to the
ordinary drying apparatus and process used in the manufacture of
sulphate of soda. The hydrochloric acid which is disengaged is collected
in ordinary apparatus used in connection with the decomposing furnace
in manufacturing sulphate of soda.
When bones have to be treated the muriatic solution is prepared with
the ordinary steps or precautions adopted for collecting the gelatine and
fatty products, and it is concentrated if necessary before being conveyed
into the furnace, but mineral phosphates are broken into large lumps
and placed in wood casks open at top, and set in an upright position,
and the acid at 15° or 18° Baumé is poured upon the phosphate, and
5 when the acid saturation is effected the liquid product is drawn off.
The solution carries the gangue away with it, and this gangue is
separated by deposit or subsidence; more phosphate is then added so as

page_text: to complete the quantity of the first charge, and fresh acid is supplied,
and so on.
It must however be understood that I do not consider the employ-
ment of any special apparatus for carrying the Invention into effect
as any part of the Invention; but the distinctive or novel character
of the Invention essentially consists in the application of the novel
reaction herein-before described and not heretofore used, by which
reaction and at a suitable temperature phosphoric acid combined with
dime in a state of acid phosphate of lime decomposes chloride of calcium,
and liberates or disengages hydrochloric acid, and absorbs the equivalent
of lime liberated or disengaged.
Having now described the nature of the said Invention, and in what
manner the same may be performed, I declare that I claim, the improved
mode of obtaining pyrophosphate of lime herein-before described.
In witness whereof, I, the said Michael Henry, have hereunto set
my hand and seal, this Twenty-first day of October, in the year
One thousand eight hundred and sixty-nine.
Witness,
E. DE PASS,
68, Fleet Street,
London.
M. HENRY. (L.S.)