IMPROVEMENTS IN PULVERULENT PREPARATIONS OF PHOSPHORIC ACID FOR USE IN THE MANU- FACTURE OF BAKING POWDERS, AND FOR OTHER PURPOSES, AND IN THE MEANS OF PRODUCING SUCH PREPARATIONS
Year: 1880

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, for an Invention of "IMPROVEMENTS IN
PULVERULENT PREPARATIONS OF PHOSPHORIC ACID FOR USE IN THE MANU-
FACTURE OF BAKING POWDERS, AND FOR OTHER PURPOSES, AND IN THE
MEANS OF PRODUCING SUCH PREPARATIONS." A communication from abroad
by Eben Norton Horsford, of Cambridge, Massachusetts, United States of
America.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 12th July 1880.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN PULVERULENT PREPARATIONS OF PHOSPHORIC
ACID FOR USE IN THE MANUFACTURE OF BAKING POWDERS, AND FOR OTHER
PURPOSES, AND IN THE MEANS OF PRODUCING SUCH PREPARATIONS." A com-
munication from abroad by Eben Norton Horsford, of Cambridge, Massachusetts,
United States of America.
In the Specification to Letters Patent granted to Alfred Vincent Newton on
behalf of the said Eben Norton Horsford, dated the 16 September 1856, No. 2161,
there was described a pulverulent preparation of phosphoric acid having the charac-
teristics and capable of the uses therein specified.
The phosphoric acid of the former preparations was however invariably combined
with limo in such proportions as to form phosphates possessing more or less acid
reaction, whether wholly united to the base, so as to constitute therewith a strictly
chemical salt, or only partially so.
By as much therefore as this combination with a base neutralized the acidity of
the phosphoric acid, by so much was its strength and efficiency diminished for the
purposes of employment with alkaline carbonates in bread-making, or in other

page_text: processes requiring the liberation of carbonic acid gas. It has been discovered how-
ever by my foreign correspondent that phosphoric acid uncombined with a base or
dissociated from acid phosphates forned therewith can be reduced to a pulverulent
condition by admixture with a neutral substance like starch, and kept inert to be
utilized after the manner of the former preparations. This discovery and the
Invention by which it has been made practically available enables the full strength
of the phosphoric acid to be preserved for the purposes of reaction upon alkaline
carbonates without the waste and expense attending its partial neutralization by
a base.
The present Invention may be efficiently carried out in the following manner :-
I-take-acid phosphate liquor, substantially such as is prepared by the process
described in the Specification to the said former Letters Patent, and-standing,-for-
example, at fifteen degrees Beaumé, or the same may be otherwise produced by
adding with constant agitation of the liquid 1600 lbs. of pulverized bone black to a
dilute solution of 1100 lbs. of oil of vitriol (one of oil vitriol to three of water), and
when the decomposition is complete, which requires some 18 hours of continuous
agitation, the emulsion will be thrown upon a cloth filter and leached. The first
portions of the liquor being above 15° Beaumé and the last portions below, it is
easy to make a liquor of precisely the strength required, and after concentrating
the liquor in porcelain-lined vessels to about one third of its volume I add thereto,
based on analysis, an equivalent of sulphuric acid for the lime present in
combination with phosphoric acid, thereby producing gypsum and setting free
phosphoric acid. The emulsion is allowed to cool, and the gypsum is separated by
filtration. The filtrate is then further concentrated in porcelain to about one fourth
of the original volume. To this after cooling I add in successive portions, with
stirring for thorough incorporation, a weight of starch inversely proportioned to the
intended acid strength of the product. Thus, if I desire that twenty parts of the
pulverulent acid shall neutralize nine parts of bicarbonate of soda, I add for every
1000 cubic centimetres of the original liquid of 15 degrees Beaumé 360 grammes of
starch. I incorporate these constituents intimately, spread the mass out to dry in :
a warm room, and when dry pulverize it.
In reducing the acid phosphate liquor described in the said former Specification
to a pulverulent condition, as therein set forth, the quantity of starch required was
in the proportion of about 100 grammes to every 1000 cubic centimetres of the
liquor, taken at 15 degrees Beaumé. It will therefore be seen that in order to
accomplish the results obtained by the present Invention a very much greater
relative proportion of the neutral substance is needed.
The pulverulent phosphoric acid so produced has been found by quantitative test
to have the same strength that the liquid alone possessed after separation of the
gypsum. It may be thoroughly mixed with dry bicarbonato of soda to form a baking
or effervescing powder, which will keep in bottles or cans without reaction, and will
when mixed with water yield carbonic acid gas for the purposes desired.
The gypsum formed by the introduction of the sulphuric acid into the acid
phosphate liquor does not impair the acid strength of the product if permitted
without being filtered off to remain as a part of it, but its elimination is preferable,
especially for pharmaceutical purposes.
As a modification of the process herein before described I may proceed as
follows:-
I tako of the leached liquor standing at 15° Beaumé, obtained by thoroughly
digesting 1600 lbs. of pulverized bone black with 1100 lbs. of oil of vitriol diluted
with three times its weight of water, and leaching the emulsion, and I concentrate
the liquor in porcelain lined vessels until it becomes a thin emulsion of crystals,
allow it to cool, and then thoroughly incorporate with constant stirring a quantity
of starch inversely proportioned to the said strength which it is desired the product
shall have; after which the mass is spread out to dry in a warm atmosphere, and
when dried it is pulverized.

page_text: If it is desired that the acid powder shall have a strength such that twenty parts of
it by weight shall neutralize nine parts by weight of bicarbonate of soda, I take for
each 1000 cubic ecntimetres of acid liquor standing at 15° Beaumé 300 grammes
of starch.
The product thus obtained is a fine dry white powder capable of being mixed
with alkaline carbonates, and kept in bottles or cans without decomposition.
In this modification of the improved process the lime remains. in the solution in
the condition of monobasic and phosphate of lime mingled with the great bulk of
free phosphoric acid, as in the original leached liquor. The product may be
applied substantially in the mannor herein before described with reference to the
1st modification..

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Henry Johnson in the Great Seal Patent Office on the 10th
January 1881.
.
.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN PULVERULENT PREPARATIONS OF PHOSPHORIC
ACID FOR USE IN THE MANUFACTURE OF BAKING POWDERS, AND FOR OTHER
PURPOSES, AND IN THE MEANS OF PRODUCING SUCH PREPARATIONS." A com-
munication-from-abroad_by_Eben Norton Horsford, of Cambridge, Massachusetts,
United States America.
The said Invention relates to improvements in pulverulent preparations of
phosphoric acid, for use more particularly in the manufacture of baking or offer-
vescing powders, and in the means of producing such preparations.
A pulveruient preparation of phosphoric acid capable of the uses above mentioned
is already known. The phosphoric acid of the former preparation was however
combined with line in such proportions as to form phosphates possessing more or
less acid reaction, whether wholly united to the base so as to constitute therewith
a strictly chemical salt, or only partially so. By as much therefore as this com-
bination with a base neutralized the acidity of the phosphoric acid, by so much was
its strength and efficiency diminished for the purposes of employment with alkaline
carbonates in bread making, or in other processes-requiring the liberation of
carbonic acid gas. It has been discovered however by any foreign correspondont
that phosphoric acid uncombined with a base or dissociated from acid phosphates
formed therewith can be reduced to a pulverulent condition by admixture with a
neutral substance like starch, and kept inert to be utilized after the manner of the
former preparations. This discovery and the Invention by which it has been made
practically available enables the full strength of the phosphoric acid to be preserved
for the purposes of reaction upon alkaline carbonates without the waste and expense
attending its partial neutralization by a base.
The present Invention may be efficiently carried out in the following manner:-
I take acid phosphate liquor as prepared by known processes for use in the said
foriner preparations, and standing, for example, at fifteen degrees Baumné, or the
same may be otherwise produced by adding with a constant agitation of the liquid
one thousand six hundred pounds of pulverized bone black to a dilute solution of
one thousand one hundred pounds of oil of vitriol (one of oil vitriol to three of
water), and when the decomposition (which requires some eighteen hours of con-
tinuous agitation) is complete, the emulsion will be thrown upon a cloth filter and
leached. The first portions of the liquor being above 15° Baumé and the last
portions below, it is easy to make a liquor of precisely the strength required, and
after concentrating the liquor in porcelain-linod vessels to about one third of its
volume, I add thereto, based on analysis, an equivalent of sulphuric acid for the
lime present in combination with phosphoric acid, thereby producing gypsum and
setting free phosphoric acid. The emulsion is allowed to cool, and the gypsum is
separated by filtration. The filtrate is then further concentrated in porcelain to
about one fourth of the original volume. To this after cooling I add in successive
portions, with stirring for thorough incorporation, a weight of starch inversely pro-
portioned to the intended acid strength of the product. Thus, if I desire that twenty
parts of the pulverulent acid shall neutralize nine parts of bicarbonate of soda, I
add for every one thousand cubic centimetres of the original liquid of fifteen
degrees Baumé three hundred and sixty grammes of starch. I incorporate these
constituents intimately, spread the mass out to dry in a warm room, and when dry
pulverize it.
•

page_text: In reducing the acid phosphate liquor to a pulverulent condition in the prepara-
tions formerly used, the quantity of starch required was in the proportion to about
one hundred grammes to every one thousand cubic centimetres of the liquor, taken
at fifteen degrees Baumé. It will therefore be seen that in order to accomplish the
results attained by the present Invention a very much greater relative proportion
of the neutral substance is needed.
The pulverulent phosphoric acid so produced has been found by quantitative test
to have the same strength that the liquid alone possessed after separation of the
gypsum. It may be thoroughly mixed with dry bycarbonate of soda to form a
baking or effervescing powder, which will keep in bottles or cans without reaction,
and will when mixed with water yield carbonic acid gas for the purposes desired.
Tho gypsum formed by the introduction of the sulphuric acid into the acid
hosphate liquor doos not impair the acid strength of the product if permitted
without being filtered off to remain as a part of it, but its elimination is proferable,
especially for pharmaceutical purposes.
As a modification of the process hereinbefore described I may proceed as
follows: I take of the leached liquor standing at 15° Baumé, obtained by
thoroughly digesting one thousand six hundred pounds of pulverized bone black
with one thousand one hundred pounds of oil of vitriol diluted with threo times its
weight of water, and leaching the emulsion, and I concentrate the liquor in porcelain
lined vessels until it becomes a thin emulsion of crystals, allow it to cool, and then
thoroughly incorporato with a constant stirring a quantity of starch inversely pro-
portioned to the acid strength which it is desired the product shall have, after
which the mass is spread out to dry in a warm atmosphere, and when dried it is
pulverized. If it is desired that the acid powder shall have a strength such that
twenty parts of it by weight shall neutralizo nine parts by weight of bicarbonato
of soda, I take for each one thousand cubic centimetres of acid liquor standing at
15° Baumé three hundred grammes of starch.
The product thus obtained is a fine dry white powder capable of being mixed
with alkaline carbonates, and kept in bottles or cans without decomposition.
In this modification of the improved process the lime remains in the solution in
the condition of monobasic and phosphate of lime mingled with the great bulk of
free phosphoric acid, as in the original leached liquor. The product may be applied
substantially in the manner herein before described with reference to the product
obtained by the first mode of carrying out the said Invention.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is,-
1st. The process of producing pulverulent phosphoric acid by treating the acid
liquid described herein so as to bring it to the condition of free phosphoric acid, and
combining the same with starch in about the proportions stated, drying and pul-
verizing, substantially as hereinbefore described.
2nd. A pulverulent preparation of phosphoric acid substantially free from com-
bination or association with any base, and kept in the state of dry powder by
admixture only with a neutral substance like starch, substantially as hereinbefore
described.
3rd. The process which consists in taking the liquor, as described herein, directly
froin the leach, boiling it down to suitable consistency, adding starch as described,
drying, and pulverizing.
4th. The preparation of free phosphoric acid and acid phosphate reduced to
pulverulent condition from the liquid, substantially such as herein described with
reference to the modified process, by concentration and admixture with a neutral
substance like starch, substantially as herein before described.

page_text: 5th. A baking or effervescing powder consisting of a mixture of pulverulent
phosphoric acid, prepared substantially as herein described, with a dry alkaline
carbonate.
In witness whereof, I, the said John Henry Johnson, have to this my
Specification set my hand and scal, this Seventh day of January, One
thousand eight hundred and eighty one.
J. HENRY JOHNSON. (L.S.)