STUDDAYANENING IN THE MANUFACTURE OF PHOSPHATES OF SODA AND POTASH
Year: 1871

page_text: LETTERS PATENT to John Thomas Way, of No. 9, Russell Road,
Kensington, in the County of Middlesex, for the Invention of
"STUDDAYANENING IN THE MANUFACTURE OF PHOSPHATES OF SODA AND POTASH."
Sealed the 30th January 1872, and dated the 1st August 1871.
COMPLETE SPECIFICATION filed by the said John Thomas Way at
the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 1st August 1871, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
THOMAS WAY, of No. 9, Russell Road, Kensington, in the County of
Middlesex, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS
IN THE MANUFACTURE OF PHOSPHATES OF SODA AND POTASH," and have petitioned
Her most Excellent Majesty Queen Victoria to grant unto me, my
executors, administrators, and assigns, Her Royal Letters Patent for
the same, and have made solemn Declaration that I am the first and
true Inventor thereof.

page_text: NOW KNOW YE, that I, the said John Thomas Way, do hereby
declare the nature of the said Invention to be as follows:-
This Invention has for its object improvements in the manufacture
of phosphates of soda and potash.
The only alkaline phosphate which is at present extensively used is
the ordinary or rhomatic phosphate of soda; this salt is usually prepared
by neutralizing phosphoric acid or acid phosphate of lime by carbonate
of soda.
Now the first part of my Invention consists in decomposing acid
phosphate of lime by means of sulphate of soda in lieu of carbonate
of soda, by which considerable economy is effected; in this case the
product in solution is acid phosphate of soda, which can be readily
converted into the rhombic phosphate and triphosphate of soda as I
shall presently show. Or I obtain this acid phosphate of soda by
decomposing common salt by phosphoric acid by the aid of heat in
the same way as it is decomposed by sulphuric acid in the manufacture
of sulphate of soda, but taking care that the heat is not sufficient to
convert the acid phosphate of soda into the compound known to
chemists as metaphosphate of soda.
From the phosphate of soda produced by either of these methods I
make the ordinary rhombic phosphate of soda by the addition of another
equivalent of soda either as caustic or carbonate of soda. And I produce
the triphosphate of soda (for the use of which in the manufacture of
soap and the cleaning of wool of woollen goods I hold Letters Patent,
dated August 3rd, 1869, No. 2328) by adding to the rhombic phosphate
of soda in the liquid condition a quantity of caustic soda equal to an
additional equivalent of soda, or by mixing with rhombic phosphate of
soda an equivalent of carbonate of soda and subjecting the mixture to
a red heat, by which the carbonate of soda is decomposed and triphos-
phate of soda is produced.
When decomposing common salt by phosphoric acid I may by the
use of an excess of such common salt and at a higher temperature
decompose more than one equivalent of such salt. In this case pyro-
phosphate of soda or a mixture of pyrophosphate and metaphosphate
of soda is obtained; this product cannot be converted into rhombic
phosphate or triphosphate of soda by the liquid method but must be

page_text: mixed with carbonate of soda and exposed to a red heat for such con-
version.
The second part of my Invention consists in producing the different
alkaline phosphates by the action of carbonate of soda or caustic soda
on the diphosphate of lime, which is a compound of two equivalents
or combining proportions of lime with one equivalent of phosphoric
acid. The methods of making diphosphate of lime are fully described
in the Specification of my Patent (No. 2344, August 14th, 1867). By
digesting diphosphate of lime with solution of caustic soda I obtain
the rhombic phosphate or the triphosphate of soda according to the
proportion of caustic soda used; the salt is dissolved out and evaporated
or crystallized for use. The insoluble phosphate of lime which results
from this process is reconverted into diphosphate of lime by any of the
methods described in my Patent. I also obtain the rhombic phosphate
of soda by decomposing diphosphate of lime by carbonate of soda in
solution with the aid of heat. This rhombic phosphate I convert into
triphosphate of soda as before described, or by digesting diphosphate
of lime with solution of carbonate of soda in the cold I obtain the same
rhombic phosphate of soda without the production of any insoluble
phosphate of lime.
In lieu of triphosphate of soda I sometimes produce a compound
phosphate of soda and potash, substituting for the third equivalents of
soda an equivalent of potash; I effect this by adding to rhombic
phosphate of soda an equivalent of caustic potash and evaporating or
crystallizing for use, or by heating an equivalent of rhombic phosphate
of soda with an equivalent of carbonate of potash.
Having now stated generally the nature of my said Invention, I
proceed to describe more particularly the modes to which I resort in
carrying it out.
I take superphosphate of lime of good quality and having ascertained
by analysis the proportion of soluble or acid phosphate of lime contained
in it, I digest it with water and add sulphate of soda in the proportion
of one equivalent for each equivalent of phosphoric acid present in the
soluble state. For instance, supposing that the superphosphate contains
14.2 per cent. of phosphoric acid in the soluble condition, then 500 lbs.
of it will contain 71 lbs. or one equivalent in lbs. of phosphoric acid,
71 being the equivalent or combining proportion of phosphoric acid.

page_text: To this quantity of superphosphate of lime I shall require to add
71 lbs of anhydrous or 161 lbs. of crystallized sulphate of soda, those
weights representing one equivalent in lbs. of the salt, the quantity
necessary to decompose the acid phosphate of 500 lbs. of superphosphate
of lime of that quality. I digest the superphosphate of lime with a
small quantity of water until it is softened and brought to a uniform
consistence, and then add the sulphate of soda also dissolved in a
small quantity of water, and mix the materials by any suitable mecha-
nical agency. I sometimes prefer to agitate the mixture by blowing
steam into it, but although the heating of the materials hastens the
process and facilitates the subsequent filtration of the liquid it is not
of absolute necessity, as the chemical change takes place equally well
in the cold. If heat is employed a digestion of one hour is sufficient
to complete the action. I then add more water and throw the whole
on a strainer of calico or linen, by which the liquid containing the acid
phosphate of soda is separated from the solid matter, which latter prin-
cipally consists of sulphate of lime. In practice I prefer to employ a
series of vessels to contain the materials from which I wish to wash
out the acid phosphate of soda, and I cause the liquor from one to pass
through another, by which more of the said acid phosphate is dissolved
in the same way as is practised by alkali makers in lixiviating the
black ash.
The foregoing process may sometimes be varied with advantage, for
instance, instead of adding the sulphate of soda to the superphosphate
as a whole, the soluble part of the latter, that is to say, the acid phos-
phate of lime, may first be dissolved out and the solution may then be
treated with sulphate of soda in the same proportion as already
prescribed, the sulphate of lime which precipitates being separated by
filtration, or the sulphate of soda may be added during the process of
making the superphosphate of lime, in which case the acid phosphate
of soda has simply to be dissolved out by lixiviation as before described.
Diphosphate of lime is also well suited for the process. In this case I act
upon diphosphate of lime by one equivalent of sulphuric acid and one
equivalent of sulphate of soda. The resulting solution of acid phosphate
of soda is dealt with as before described, or I dissolve the diphosphate
of lime in hydrochloric acid, and add first one equivalent of sulphuric
acid and then one equivalent of sulphate of soda. I filter the liquor
and evaporate it to dryness, collecting and condensing the hydrochloric

page_text: acid vapours that are given off. I mix the dry product with two
equivalents of carbonate of soda and heat the mixture to gentle redness
in a furnace, obtaining anhydrous triphosphate of soda. The compound
of chloride of calcium and acid phosphate of lime which I call chloro-
phosphate of lime, and which is described in the Specification of my
Patent No. 1851, dated 14th July 1871, may also be employed. When
using chlorophosphate of lime as a source of phosphoric acid I proceed
the same way as when treating a solution diphosphate of lime in hydro-
chloric acid as above described.
I would observe that by superphosphate of lime I mean to indicate
the ordinary substance so called, and which is produced by the action
of sulphuric acid on burnt bones or mineral phosphate. By preference
the material so employed should be free from organic and coloring
matter; it should not contain any large proportion of free phosphoric
acid, nor should it contain much undecomposed or insoluble phosphate
of lime, which would be lost and wasted in the residual sulphate of lime.
The solution of acid phosphate of soda obtained by either of these
processes will contain a certain quantity of sulphate of lime which will
be greater in proportion to the dilution of the liquor; for this reason as
well as to save evaporation it is desirable to avoid unnecessary dilution.
The greater part of this sulphate of lime may be removed by evaporation
in jacketted vessels heated by steam; such evaporation may continue
until the liquid becomes syrupy, the sulphate of lime being then
separated by filtration through calico or linen.
To convert the phosphate of soda so produced into ordinary rhombic
phosphate of soda it is only necessary to add an equivalent of caustic
soda or carbonate of soda, the use of the latter being the more economical
of the two; the necessary quantity of either of these substances is easily
ascertained. If carbonate of soda be employed it will be sufficient to
add it so long as effervescence takes place. The quantity of caustic
soda must be determined by calculation. To a solution of acid phosphate
of soda obtained as before described and containing 71 lbs. or one
equivalent in pounds of phosphoric acid, a quantity of soda ash con-
taining 31 lbs. of real soda or of solution of caustic soda containing a
like amount of real soda will require to be added. The addition of
caustic soda or its carbonate will produce a precipitate due to the
presence of sulphate of lime and sometimes of oxide of iron; this
precipitate being removed by filtration. The clear liquid is a more or

page_text: less pure solution of rhombic phosphate of soda, which may be crystal-
lized out by well known treatment.
If it is desired to produce the triphosphate of soda a further addition
of one equivalent of caustic soda must be made to the solution of
rhombic phosphate of soda, and in this case the use of the caustic or
carbonate of soda is not optional, but it is necessary to use caustic soda,
as the carbonate will not combine with rhombic phosphate of soda in the
liquid way. It is obvious that in making triphosphate of soda the whole
of the alkali requisite may (if caustic soda be used) be added direct to
the acid phosphate of soda, or if one equivalent is to be used in the
shape of carbonate of soda this must be added, and when the effer-
vescence has ceased the caustic soda may be put in. I have before
explained that rhombic phosphate of soda may be converted into
triphosphate of soda by heating it to redness with carbonate of soda.
When wishing to employ this method of obtaining triphosphate of soda
from acid phosphate of soda prepared as described I add to the acid
phosphate of soda two equivalents or combining proportions of carbonate
of soda or a quantity of soda ash or other form of carbonate of soda,
containing 62 lbs. of real soda for every 71 lbs. of phosphoric acid in the
acid phosphate, and after separating the precipitate produced I evaporate
the liquor to dryness in a reverberatory furnace and heat to gentle
redness; it is sometimes necessary for complete conversion to break up
the product so obtained by passing it through stones or rollers and to
furnace it a second time.
In order to make a compound triphosphate of soda and potash Is
substitute in the foregoing processes one equivalent or combining pro-
portion of potash for the third equivalent of soda. If the triphosphate
of soda and potash is to be made in the wet or liquid way the potash
must be employed in the caustic state, but the salt may be produced
from carbonate of potash or pearl ashes by furnacing the rhombic
phosphate of soda with this substance in the same way as has already
been described for the production of triphosphate of soda.
I would observe that this compound phosphate of soda and potash
is very useful for cleansing and washing purposes, but as the third
equivalent of alkali in an alkaline triphosphate is alone available as a
detergent, it is essential that in producing the salt the potash should
only be added when two equivalents of soda are already in combination
with phosphoric acid.

page_text: In dealing with that part of my Invention which has reference to
the decomposition of common salt in phosphoric acid I proceed as
follows:-
I treat superphosphate of lime with an extra proportion of sulphuric
acid, or what is the same I act upon mineral or other phosphate of
lime with sufficient sulphuric acid to unite with the whole of the lime
and set free the phosphoric acid; this phosphoric acid I dissolve out
with water by lixiviation. I evaporate the solution and filter in order
to separate sulphate of lime which has dissolved, by which means I
obtain a concentrated solution of phosphoric acid; when desiring to
make acid phosphate of soda I add to this solution common salt in the
proportion 58 parts of common salt for every 71 parts of phosphoric
acid. I heat the mixture gently condensing, if need be, the vapours
of hydrochloric acid which escape. The product is acid phosphate of
soda which I convert into rhombic phosphate or triphosphate of soda
as before described. If the object is to make triphosphate of soda a
further portion of the alkaline base may be obtained from common
salt by heating the phosphoric acid with an excess of the salt to
redness. In this case to a solution containing 71 parts of phosphoric
acid I add 116 parts of common salt or even more, and after evapo-
ration by heat as before I subject the mixture to a red heat in a
reverberatory furnace, preferring to project it by degrees on to the
heated bed of such furnace. I examine the products to ascertain
the proportion of soda which has thus become united with phos-
phoric acid, and I add so much soda ash or carbonate of soda as
will be sufficient to make it into triphosphate of soda, and again
subject the mixture to heat in the furnace. The product is anhydrous
triphosphate of soda mixed with common salt; to purify it I dissolve
in water, and crystallize out the triphosphate of soda.
In producing rhombic phosphate of soda or triphosphate of soda or
from diphosphate of lime I proceed as follows:-I take any convenient
quantity of solution of caustic soda of a strength of from 5 to 10 per
cent. of the caustic alkali of specific gravity 1.07 to 1-15, and having
heated it I add by degrees diphosphate of lime until the liquor when
tested by solution of nitrate of silver ceases to give a black or brown
precipitate, and the precipitate is of a pure yellow colour. I separate
the solution and wash the insoluble portion. The liquid so obtained is
a solution of triphosphate of soda, which may be crystallized or other-
wise dealt with. By continuing the addition of diphosphate of lime

page_text: after the liquor has ceased to be rendered black by addition of nitrate
of silver I obtain the rhombic phosphate of soda. The quantities
required for these processes are approximately as follows:-To produce
triphosphate for every 93 parts or (3 equivalents) of real caustic soda
and 462 parts or (3 equivalents) of diphosphate of lime will be required,
for rhombic phosphate of soda 62 parts or (2 equivalents) of caustic
soda will be required to the same quantity (462 parts) of diphosphate
of lime. I should observe that only ths of the phosphoric acid of the
diphosphate of lime is thus made to combine with soda. The insoluble
portion is phosphate of lime containing a smaller proportion of phos-
phoric acid, it can be reconverted into diphosphate of lime by one or
other processes described in my Patent (No. 2344, Aug. 14th, 1867).
Carbonate of soda may be employed to produce rhombic phosphate of
soda instead of caustic soda in the same manner and in the same pro-
portions as now described, but I prefer the use of caustic soda. Diphos-
phate of lime is also decomposed by carbonate of soda in the cold, but
the chemical change is of another character from that last described.
To 154 parts or (one equivalent) of diphosphates of lime I add 212
parts or 4 equivalents of carbonate of soda, or a quantity of soda ash
equal to the above. I mix the materials intimately and add water
from time to time so long as the mixture thickens; after a delay which
should not be less than 48 hours I dissolve out of water. The solution
contains rhombic phosphate of soda. The insoluble part is a compound
of carbonate of lime and carbonate of soda in single equivalents. I
recover the carbonate of soda by boiling this compound with water, by
which it is decomposed into carbonate of lime and carbonate of soda.
I have described the manufacture by my new processes of phosphates
of soda, but the same description applies to the production of the
corresponding salts of potash, substituting the word potash for that of
soda in the directions now given.
Having thus described the nature of my said Invention, and the
manner of performing the same, I would have it understood that I
claim,―
First. The manufacture of acid phosphate of soda by the decomposition
of acid phosphate of lime by means of sulphate of soda, and the con-
version of the acid phosphate of soda into rhombic phosphate and
triphosphate by the addition of soda cither in the caustic state or as
carbonate, substantially as described.

page_text: Second. The manufacture of acid phosphate of soda by the decom-
position of chloride of sodium by means of phosphoric acid, and the
conversion of the said acid phosphate of soda into rhombic phosphate
or triphosphate by the addition of soda either in the caustic state or as
carbonate, substantially as described.
Third. The manufacture of triphosphate of soda by heating together
chloride of sodium and phosphoric acid, by which means for each
equivalent of phosphoric acid more than an equivalent of chloride of
sodium is decomposed, and afterwards heating the product with soda,
the soda being used by preference in the state of carbonate and heat
being applied, substantially as described.
Fourth. The manufacture of triphosphate of soda by mixing the
rhombic phosphates of soda with carbonate of soda, and heating the
mixture in a reverberatory furnace, substantially as described.
Fifth. The manufacture of rhombic phosphate of soda and triphos-
phate of soda by the decomposition of diphosphate of lime by means
of soda, either in the caustic state or as carbonate, substantially as
described.
Sixth. The manufacture of phosphates of potash by processes similar
to those above claimed in respect to phosphates of soda.
Seventh. The manufacture of phosphates containing both soda and
potash by processes similar to those above claimed in respect to phos-
phate of soda, and especially of a triphosphate in which two of the
equivalents of base are soda, and the third is potash.
In witness whereof, I, the said John Thomas Way, have hereunto
set my hand and seal, this First day of August, in the year of
our Lord One thousand eight hundred and seventy-one.