IMPROVEMENTS IN THE MANUFACTURE OF SUPERPHOSPHATE OF LIME SO AS TO CONTROL ITS SOLUBLE CONDITION
Year: 1871

page_text: J
LETTERS PATENT to Benjamin Tanner, of New Brighton, in the
County of Chester, Manufacturing Chemist, for the Invention of
r IMPROVEMENTS IN THE MANUFACTURE OF SUPERPHOSPHATE OF LIME SO AS TO
CONTROL ITS SOLUBLE CONDITION."
Sealed the 29th December 1871, and dated the 7th July 1871.
PROVISIONAL SPECIFICATION left by the said Benjamin Tanner at the
Office of the Commissioners of Patents, with his Petition, on the
7th July 1871.
I, BENJAMIN TANNER, of New Brighton, in the County of Chester,
Manufacturing Chemist, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN THE MANUFACTURE OF SUPERPHOSPHATE OF LIME SO
AS TO CONTROL ITS SOLUBLE CONDITION," to be as follows:-
In the first instance it may be observed that the term "superphosphate
of lime" is usually applied to those phosphates of lime which have been
manufactured in such a manner that the proportion of phosphoric
acid in combination with the lime has been increased over and above
the proportion existing in the unmanufactured phosphate of lime

page_text: and from these circumstances the term "superphosphate" has been
aderived.
The general practice (which is well known to persons conversant
with chemical manufactures) is to convert the tri-calcic phosphate into
mona-calcic (or soluble) phosphate of lime and thereby to change an 5
insoluble material so as to impart to it a very soluble condition. The
soluble phosphate thus formed is by reason of its great solubility
unsuited for certain soils and climates. It has therefore become desirable
to produce superphosphates of lime having an intermediate character,
so that, whilst sufficiently soluble to be steadily available for the purposes 1
of vegetation they shall not be easily washed out of the soil to which
they are applied.
It is in some cases advantageous to modify the condition of the slowly
soluble superphosphate of lime by an increase of its solubility so as to
suit the varying requirements of soil or climate. These results are 1
economically and advantageously obtained by the processes herein-after
described.
For the convenience of description and reference the following para-
graphs, in which the processes embraced by this Invention are described,
and in which the same principles are involved, are numbered conse-
cutively.
1. Phosphate of soda or phosphate of potash or mixture thereof are
mixed with sulphate of lime with or without water and exposed to
heat, whereby a process of decomposition takes place which produces
slowly soluble superposphate of lime and sulphate of soda or sulphate
of potash or mixtures thereof. It is preferred in practice to mix these
materials in the proportion of two equivalents of sulphate of lime for
each equivalent of phosphoric acid in the phosphate of soda or phosphate
of potash or mixtures thereof employed. The superphosphate of lime
thus formed is freed from any sulphate of soda or sulphate of potash or
mixtures thereof by means of water either by filtration, decantation, or
otherwise, and when desirable it is dried on brick floors heated by means
of flues or by some other convenient drying arrangement (which,
however, forms no part of the present Invention). Any sulphate of
soda or sulphate of potash or mixtures thereof in the solution is or are
obtained by evaporation.
2. Any of the forms of phosphate of soda or of phosphate of potash
or mixtures thereof is or are treated with lime or sulphate of lime,

page_text: or any of the forms of carbonate of lime or of phosphate of lime, or
chloride of calcium, or mixtures thereof, either with or without being
in solution, but preferably in solution, and either with or without the
assistance of heat, but preferably with such assistance in the form of
steam, superheated steam, hot air, or otherwise. The proportions in
which these are by preference mixed are regulated so that for each
equivalent of phosphoric acid present or added there shall be not less.
than two equivalents of lime or calcium also present. The product will
be slowly soluble superphosphate of lime, which is
and dried as herein-before described in paragraph 1.
purified by water
3. Phosphoric acid or phosphoric acid and water are mixed with
sulphate of lime and chloride of 'sodium or chloride of potassium or
mixtures thereof and exposed to heat, whereby a process of decomposition
takes place which results in the formation of slowly soluble super-
phosphate of lime and sulphate of soda or sulphate of potash or mixtures.
thereof which are separated as already described. It is preferred to mix
these materials in the proportion of one equivalent of phosphoric acid
with not less than two equivalents of sulphate of lime and two equi-
valents of chloride of sodium or two equivalents of chloride of potassium
or proportional mixtures thereof. If too much heat is employed in any
of the before-mentioned processes pyrophosphate of lime is formed,
which (with or without the separation of the salts mixed with it) is
treated with hydrochloric acid and water or nitric acid and water, or
mixtures thereof, and obtained in the form of slowly soluble super-
phosphate of lime by careful evaporation preferably at a temperature
not exceeding 212° Fahrenheit.
4. Solutions of the crystals formed by the action of strong hydro-
chloric acid or phosphoric acid or mixtures thereof upon phosphate of
lime are treated with lime or any of the forms of carbonate of lime,
or mixtures thereof, by which means the phosphoric acid present is
precipitated in the form of slowly soluble superphosphate of lime from
which any chloride of calcium is run off in solution and the super-
phosphate of lime is washed on filter beds or other suitable arrangements
as is well understood, and may then be dried as described in the paragraph
hereof numbered 1.
5. Crystals formed by the action of strong hydrochloric acid on
phosphate of lime either with or without solution in water are treated
with phosphoric acid, or sulphuric acid, or oxalic acid, or mixtures

page_text: thereof, by preference in such proportion' that after such admixture
there shall be for each equivalent of phosphoric acid present two equi-
valents of lime or calcium remaining available for or in combination
with the phosphoric acid. The mixture may be exposed to gentle heat
to facilitate the decomposition, by which treatment slowly soluble super-
phosphate of lime will be formed, which may be washed and dried as
before described.
6. When the slowly soluble superphosphate of lime is required in any
more rapid condition of solubility, this object can be attained by propor-
tionately decreasing the per-centage of the lime it contains, this object
being effected by mixing with it as much phosphoric acid or sulphuric
acid, or oxalic acid, or mixtures thereof, as shall be required for the
reduction to be made in the proportion of lime, and if necessary by
warming the mixture on a hot floor or otherwise in order to perfect
the action and to obtain the product in the required condition. When
the superphosphate of lime is required in a very high condition of
solubility or in great purity the soluble phosphate is dissolved out by
the use of water and evaporated.
.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Benjamin Tanner in the Great Seal Patent Office
on the 6th January 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BENJAMIN
TANNER, of New Brighton, in the County of Chester, Manufacturing
Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventh day of July, in the year of
our Lord One thousand eight hundred and seventy-one, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Benjamin Tanner, Her, special licence
that I, the said Benjamin Tanner, my executors, administrators, and
assigns, or such others as I, the said Benjamin Tanner, 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

page_text: Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN THE MANU-
FACTURE OF SUPERPHOSPHATE OF LIME SO AS TO CONTROL ITS SOLUBLE CONDITION,"
upon the condition (amongst others) that I, the said Benjamin Tanner,
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 imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Benjamin Tanner, 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, that is to say :-
In the first instance it may be observed that the term " super-
phosphate of lime" is usually applied to those phosphates of lime which
have been manufactured in such a manner that the proportion of phos-
phoric acid in combination with the lime has been increased over and
above the proportion existing in the unmanufactured phosphate of lime,
and from these circumstances the term "superphosphate " has been
derived. The general practice (which is well known to persons con-
versant with chemical manufactures) is to convert the tri-calcic into
mono-calcic phosphate (soluble phosphate of lime), and thereby to change
an insoluble material so as to impart to it a very soluble condition. The
soluble phosphate thus formed is by reason of its great solubility
unsuited for certain soils and climates: It has therefore become desirable
to produce superphosphates of lime having an intermediate character so
that whilst sufficiently soluble to be steadily available for the purposes
of vegetation they shall not be easily washed out of the soil to which
they are applied. It is in some cases advantageous to modify the con-
dition of the slowly soluble superphosphate of lime by an increase of
its solubility so as to suit the varying requirements of soil or climate
These results are economically and advantageously obtained by the
processes herein-after described.
For the convenience of description and reference the following
paragraphs, in which the processes embraced by my said Inventions are
described, are numbered consecutively.
1. Phosphate of soda or phosphate of potash or mixtures thereof are
mixed with sulphate of lime with or without water and exposed to

page_text: .
heat, whereby a process of decomposition takes place which produces
one
slowly soluble superphosphate of lime and sulphate of soda or sulphate
of potash, or mixtures thereof. It is preferred in practice to mix these
materials in the proportions of two equivalents of sulphate of lime
for each equivalent of phosphoric acid in the phosphate of soda or
phosphate of potash or mixtures thereof employed, that is to say,
hundred and thirty-six hundredweights of anhydrous sulphate of lime (or
its equivalent in any other form or condition) are added for every seventy-
one hundredweights of phosphoric acid in the phosphate of soda or phos-
phate, of potash or mixtures thereof used. Taking for example the
action of phosphate of soda with sulphate of lime, in practice one ton of
commercial sulphate of lime containing eighty per cent. of anhydrous
sulphate of lime would be intermixed with about forty-two hundred-
weights of ordinary phosphate of soda containing nearly twenty per
cent. of phosphoric acid, the proportions being varied and regulated
according to the strength and purity of the material used. These
materials being intermixed are exposed in shallow evaporating pans or
some arrangement similar to that employed in the manufacture of salt
cake or of soda ash or any suitable arrangement in which the temperature
of the mixture can be raised (by preference not beyond 280° Fahrenheit,
by means of heat being applied in the usual manner to the bottom of
the vessel), so as to fuse the phosphate or phosphates in the presence
of sulphate of lime, and in some cases such heat may be advantageously
employed in conjunction with the passage of steam or superheated
steam or mixtures of steam and hot air into, over, or through the
mixture, the temperature so supplied ranging from 212° to 450° Fahren-
heit according to which of the sources of heat has been employed as
herein-after more fully explained, at the same time such combination is
not necessary, as either of the methods of applying heat can be employed
separately and decomposition takes place. yielding a slowly soluble
superphosphate of lime and sulphate of soda. It is also desirable in
some cases to add water to compensate for loss by evaporation and to
stir the mixture from time to time until the decomposition is completed.
The same results can be obtained by adding water to the mixed materials
placed in a vessel fitted with rotating arms or any other suitable
arrangement (as will be well understood), by which the whole is kept
in motion, or by dissolving the phosphate in water and then stirring in
the sulphate of lime as above described, the temperature in either case
being raised by either of the methods of applying heat above-named

page_text: or by any other suitable means, in either case the superphosphate of
lime formed is freed from sulphate of soda by means of water either
by filtration, decantation; or otherwise, and when desirable it is dried
on brick floors heated by means of flues or by some other convenient
drying arrangement (which however forms no part of my said Inven-
tion), and the sulphate of soda in the solution is obtained by evaporation
either as crystals or in any other form that may be desired.
2. Any of the forms of phosphate of soda, or phosphate of potash,
or mixtures thereof, is or are treated with lime or sulphate of lime, or
any of the forms of carbonate of lime or of phosphate of lime or chloride
of calcium, or mixtures thereof, either with or without being in solution
and either with or without the assistance of heat, but preferably with
such assistance in the form of steam, superheated steam, hot air, or
otherwise. The proportions in which these are by preference mixed
are regulated so that after such admixture for each equivalent of
phosphoric acid present there shall be not less than two equivalents
of lime or calcium also present, that is to say, for every seventy-one
hundredweights of phosphoric acid present or added there shall be not
less than fifty-six hundredweights of lime or forty hundredweights of
calcium also present. The general line of procedure may be illustrated
by describing the treatment of phosphate of soda with lime. To about
three hundred and fifty-five hundredweights of ordinary phosphate of
soda containing nearly twenty per cent. of phosphoric acid dissolved in
water in some convenient vessel (the latter being fitted with a rotating
agitator and a steam pipe for the purpose of raising the température
by means of steam or hot air, or by any other means) about fifty-six
hundredweights of caustic lime (which would be contained in one
hundred and twelve hundredweights of commercial lime containing
fifty per cent. lime) is added, having by preference been previously.
obtained in the condition of milk of lime by intermixture with water
in a convenient vessel and raised to about 120° Fahrenheit by the aid
of steam or hot air, and the mixture kept in a state of agitation until
the decomposition is completed, or water may be added to the above-
mentioned mixture and the whole treated in a similar manner, or the
above-named mixture may be placed in any convenient vessel and the
whole evaporated to a pasty condition and fused together by cither of
the methods detailed in paragraph hereof numbered I, till the decom-
position is completed, regulating the temperature so that it does not
rise by preference much above 212° Fahrenheit, although the product

page_text: is not injured by a dry heat of a temperature below 280° Fahrenheit
or by superheated steam of a temperature of from 400° to 450° Fahren-
heit.
On the same principle any of the above-named lime or calcium
compounds or mixtures thereof may be employed, regulating the quantity
according to their equivalent or combining proportion (which will be
well understood by persons conversant with chemical operations) and
the purity and strength of the materials employed, subsequently treating
the mixture as before described. When any phosphate of soda or
phosphate of potash or mixtures thereof (having less than two equi-
valents of soda or potash or mixtures thereof combined with one
equivalent of phosphoric acid) is or are employed, mixtures of the
before-named lime or calcium compounds may be advantageously used,
so that after such admixture for every equivalent of phosphoric acid
present there shall be not less than two equivalents of lime or calcium
also present. Take, for example, the action of mono-sodic phosphate
(acid phosphate of soda) and a mixture of sulphate of lime and lime
(say one equivalent or combining proportion of each). That quantity
of mono-sodic phosphate containing seventy-one hundredweights of
phosphoric acid is taken and to it is added a mixture sixty-eight
hundredweights of sulphate of lime, and twenty-eight hundredweights
of caustic lime, which would be respectively contained in eighty-five
hundredweights of commercial sulphate of lime containing eighty per
cent. anhydrous sulphate of lime, and fifty-six hundredweights of com-
mercial lime containing fifty per cent. caustic lime, and the mixture
then treated by any of the processes herein described. On the same
principle any mixture of the above-named lime or calcium compounds
may be employed, varying the proportion according to the strength and
purity of the materials employed. In either case the product will be
slowly soluble superphosphate of lime, which is purified by water from
any caustic alkali or alkaline salt or mixtures thereof present and dried
as herein-before described in the paragraph hereof numbered 1, the
latter being obtained by evaporation in the desired condition.
3. Phosphoric acid or phosphoric acid and water are mixed with
sulphate of lime and chloride of sodium or chloride of potassium, or
mixtures thereof, and exposed to heat, whereby a process of decomposition
takes place which results in the formation of slowly soluble super-
phosphate of lime and sulphate of soda or sulphate of potash, or mixtures
thercof. It is preferred to mix these materials in the proportion of one
equivalent of phosphoric acid with not less than two equivalents of

page_text: sulphate of lime and two equivalents of chloride of sodium, or two
equivalents of chloride of potassium, or proportional mixtures thereof,
that is to say, for every seventy-one hundredweights of phosphoric acid
are added not less than one hundred and thirty-six hundredweights of
anhydrous sulphate of lime (or its equivalent in any other form or con-
dition), and one hundred and seventeen hundredweights of chloride of
sodium, or one hundred and forty-nine hundredweights of chloride of
potassium, or proportional mixtures thereof. With a view to the practical
attainment of this object about three hundred and fifty-five hundred-
weights of commercial phosphoric acid (containing twenty per cent. of
phosphoric acid) mixed with one hundred and seventy hundredweights of
commercial sulphate of lime (containing eiglity per cent. of anhydrous
sulphate of lime) and one hundred and thirty hundredweights of chloride
of sodium (containing ninety per cent. of pure chloride of sodium) or one
hundred and sixty-five and a half hundredweights of chloride of potassium
(containing ninety per cent. of pure chloride of potassium) or proportional
mixtures of chloride of sodium and chloride of potassium (varying the
proportions according to the strength and purity of the materials used)
may be placed in an evaporating pan moistened by the addition of water
to the condition of a thin paste or limpid mass and then heated carefully
by fire or by hot air at a temperature by preference not exceeding
280° Fahrenheit either with or without the conjoined action of super-
heated steam not exceeding 400° or 450° Fahrenheit (but preferably
with such assistance) until the decomposition is completed, the mass
being stirred and water added from time to time as may be required.
Any of the processes detailed in paragraph hereof numbered 1 may be
employed, continuing the application of heat in either of the modes
described as therein set forth. By these means the mixture is more or
less freed from chlorine, which may be condensed or utilized in the
ordinary manner. The residue is converted into slowly soluble super-
phosphate of lime and sulphate of soda or sulphate of potash, or
mixtures thereof. The superphosphate of lime thus formed is purified
by means of water from soluble matter present, and both treated as
herein-before described in the paragraph numbered 1.
When commercial phosphoric acid contains sulphuric acid as an
impurity the quantity thereof should be estimated and an equivalent
quantity of chloride of sodium or chloride of potassium, or mixtures
thereof, used in addition to the quantities above named, that is to say,

page_text: for every forty hundredweights of anhydrous sulphuric acid so present
5S-5 hundredweights of pure chloride of sodium or 745 hundred-
weights of pure chloride of potassium or proportional mixtures thereof
should be added in addition to that above named, and the processes
carried on as already described. It is obvious that slowly soluble super-
phosphate of lime may also be made by a combination of the pro-
cesses described in paragraphs hereof numbered 2 and 3 respectively,
that is to say, by regulating the proportion of chloride of sodium. or
chloride of potassium, or mixtures thereof, so as to form mono-sodic or
mono-potassic phosphate or tri-sodic or tri-potassic phosphate, or any
mixture of any of the phosphates of soda or of potash, and treating them
in conjunction with any of the lime or calcium compounds, or mixtures
thereof, mentioned in paragraph hereof numbered 2 in the manner
above-mentioned, as the same principle and processes apply equally
in such cases. If too much heat is employed in any of the before
mentioned processes pyrophosphate of lime is formed, which (with or
without the separation of the salts mixed with it) is treated with hydro-
chloric acid and water or with nitric acid and water, or mixtures thereof,
and obtained in the form of slowly soluble superphosphate of lime by
careful evaporation of the solution and subsequent decomposition of
the solid matter preferably at a temperature neither exceeding 280°
Fahrenheit when dry heat is used, nor exceeding 450° Fahrenheit when
superheated steam is employed. When any mixture of steam and hot
air is employed in any of the processes herein-named the temperature
is regulated according to the proportion in which they are mixed, that
is to say, the temperature of the mixture is decreased as the proportion
of hot air to steam is increased.
4. Solutions of the crystals formed by the action of strong hydro-
chloric acid or phosphoric acid or mixtures thereof upon phosphate of
lime as described in the Specification of an Invention for "Improvements
in the Manufacture of Superphosphate of Lime" for which Letters
Patent have been granted to me bearing date the Twenty-eighth day
of April One thousand eight hundred and seventy-one, No. 1147, are
treated with lime or any of the forms of carbonate of lime, or mixtures
thereof, by which means the phosphoric acid present is precipitated in
the form of a slowly soluble superphosphate of lime.
In carrying out this process it is found convenient to reduce the
materials to be added to the solution into a fine powder either by

page_text: the aid of water or by a crushing arrangement, and to intermix it
with sufficient water so that it shall be in a soft and limpid condition
before being added to the said solution of phosphate of lime.
It is also desirable in some cases to warm the mixture of the said lime
compounds after the addition of water by the aid of steam or hot air
prior to its intermixture with the said solution of phosphate. This
mixture of the said lime compounds with water is conveniently effected
by agitation in a wooden vat fitted with a central shaft and stirring
arms. From the vat so employed the mixture may be run into a
second vat fitted with similar agitating arrangements containing the
solution of phosphate. Such addition may be made gradually under
the control of a tap or other means for regulating the supply, and should
be continued until upon an examination of the solution by ordinary
chemical tests being made it is shown to be free from phosphoric acid
and the liquor has a neutral or alkaline reaction. The agitation of the
liquid should be maintained so as to prevent any subsidence of solid
matter, and the temperature may be advantageously kept up to about
120° Fahrenheit until the precipitation is completed. The mixture may
then be run into a draining tank fitted with a false bottom covered
with a draining cloth, which whilst allowing the clear liquor to run
through will hold back the precipitated phosphate. By passing water
through the bed of slowly soluble superphosphate thus formed it is
casily freed from chloride of calcium, and when so washed it can be
dried upon brick floors heated by flues or by some other drying
arrangement, as is well understood.
5. Crystals formed by the action of strong hydrochloric acid on
phosphate of lime, either, with or without solution in water, are treated
with phosphoric acid, or sulphuric acid, or oxalic acid, or mixtures
thereof, by preference in such proportion that after such admixture
there shall be for every seventy-one hundredweights of phosphoric acid
present fifty-six hundredweights of lime or forty hundredweiglits of
calcium remaining available for or in combination with the phosphoric
acid.
When the crystals are dissolved in water the amount of phosphoric
acid and lime or calcium present in such solution is determined by
chemical analysis. Thus supposing, for example, thirty-six tons of sucli
solution contained seventy-one hundredweights of phosphoric acid, and
eighty-four hundredweights of lime, or sixty hundredweights of calcium,

page_text: it would require either 1775 hundredweights of commercial phosphoric
acid containing twenty per cent. of phosphoric acid, or 66.7 hundred-
weights of commercial sulphuric acid containing sixty per cent. of
anhydrous sulphuric acid, or 61.5 hundredweights of crystallised oxalic
acid, or any proportional mixture thereof, to bring the phosphoric acid
and lime or calcium into the desired proportions. The acid being
more or less diluted with water the admixture may be conveniently
accomplished in a wooden vessel fitted with a rotating agitator, by
which the whole is kept in motion until thoroughly intermixed, and
when the chemical action is completed the mixture is evaporated and
gentle heat. (by which term I mean that form of heat which has been
softened down and rendered less liable at a given temperature. to
abstract basic water from the phosphate by the intermixture of steam)
in the form of steam or superheated steam, or mixtures of steam and
hot air is applied, whereby the decomposition is facilitated and effected
more rapidly and with greater certainty. This application of heat is
usually continued until acid fumes cease to come off, and the product
thus formed is slowly soluble superphosphate of lime in a more or less
•

page_text: by the same means as above described, which results in the formation
of a slowly soluble superphosphate of lime.
The hydrochloric acid given off by any of the foregoing processes is
either condensed or utilized by any of the arrangements usually adopted
for such purposes, and which are well known to persons conversant with
manufacturing chemistry.
6. When the slowly soluble superphosphate of lime is required in
any more rapid condition of solubility, this object can be attained by
proportionally decreasing the per-centage of the lime it contains, this
object being effected by mixing it with as much phosphoric acid or
sulphuric acid, or oxalic acid, or mixtures thereof, as shall be required
for the reduction to be made in the proportion of lime, and if necessary,
by warming the mixture on a hot floor or other convenient arrangement,
in order to perfect the action and to obtain the product in the required
condition. When the superphosphate of lime is required in a very
high condition of solubility or in great purity the soluble phosphate is
dissolved out by the use of water and evaporated.
It should be observed that the proportions of the substances employed
for the purposes of my said Invention are not in all cases precisely
such as are herein-before mentioned, as such proportions may (as
will be well understood by persons conversant with the manufacture
of analogous chemical products) in some instances according to the
state of the materials used in regard to the admixture of impurities
or foreign matters be varied without departing from the principle of my
said Invention.
-
Having thus declared and ascertained the nature of my Invention,
and in what manner the same is to be performed, I would observe in
conclusion that I do not claim as forming my Invention the production
of a compound of acid or mono-phosphate of lime with chloride of
calcium in the proportion of one equivalent of cach; but what I con-
sider novel and original, and therefore claim as the Invention secured
to me by the said herein-before in part recited Letters Patent are,―
First. The production of superphosphate of lime in the manner and
for the purposes substantially as herein-before described and set forth.
And, secondly. The production of soda or potash in a caustic con-
dition, or in combination with an acid or any mixtures thereof, as bye-
products arising in the manufacture of slowly soluble superphosphate of

page_text: described and set forth.
In witness whereof, I, the said Benjamin Tanner, have hereunto
- set my hand and seal, this Third day of January, in the year
of our Lord One thousand eight hundred and seventy-two.
BENJAMIN TANNER. (L.S.)