Improvements in the Manufacture of Soluble Metallic Phosphate Compounds.
Year: 1894

page_text: Date of Application, 7th July, 1894
Complete Specification Left, 2nd Apr.. 1895-Accepted, 4th May, 1895
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Soluble Metallic Phosphate
Compounds.
I, CARL RASPE of 21 Sofienstrasse, Berlin in the Empire of Germany,
Manufacturer, do hereby declare the nature of this invention to be as follows:-
This invention relates to the manufacture of soluble phosphate compounds of
alkali metals on the one hand, and of the metals tin, copper, zinc, bismuth and
antimony, on the other hand by a melting process. These compounds have either
slightly acid or alkaline reactions and more particularly the double salts of tin,
antimony and bismuth are characterised by the great stability of their solutions in
water, as these salts are only decomposed by water either extremely slowly or not
at all. By the production of such soluble double compounds the solutions of
which in water are as stable as possible, an important technical application is
secured for the above named metals more particularly in dyeing, electro-metallurgy
and medicine.
Experiments made for this object have shown that, by melting together the
metallic oxides in question with alkali and phosphoric acid, very soluble compounds
may be obtained, if the proportions be so chosen that the resulting substance
contains not less than 1 atom of phosphorus to two atoms (monovalent) of metal
plus alkali metals. If more metallic oxide be employed, a corresponding quantity
of tri-metallic phosphate or excess metallic oxide would result. If so much
metallic oxide be employed that the metal of the same and the alkali metal of the
alkaline substance are sufficient to convert all the phosphoric acid present into
tri-metallic phosphate, only such insoluble trimetallic phosphate is produced and no
soluble metallic phosphate. If, therefore, more particularly soluble metallic
phosphate is to be produced by this process, in no case must so much metallic oxide
plus alkali be present in the melting mixture that for every atom of phosphorus
there are three atoms of metal (monovalent) of the metallic oxide and alkali; the
highest practical limit is two atoms of metal (monovalent) of the metallic oxide
and alkali, to one atom of phosphorus. As in practice it is desirable to obtain a
soluble product as rich as possible in metallic oxide, the minimum limit for the
metallic oxide material must be so chosen that it still exceeds the proportion of
one atom of metal (monovalent) of the metallic oxide and alkali, to one atom of
phosphorus even although a larger quantity of phosphoric acid does not injure the
solubility.
It is practically impossible to use so little metallic oxide or so much phosphoric
acid that a double metaphosphate is produced on account of the strongly acid
character of the melting mixture before and during the melting, as the melting
vessels made of such materials as are available in practice, are not sufficiently
durable to stand such a mixture.
The process described in this invention is accordingly generally carried out by
melting metallic oxide together with alkali and phosphoric acid, the above named
limits in proportioning the quantities being retained, the result of this being a
vitreous somewhat hygroscopic substance. The proportions of the substances in
these mixtures, which must produce clear, soluble, phosphate double compounds of
metal and alkali, are indicated in the following examples, which serve to more
particularly describe and explain this invention:

page_text: only be used when already formed, but may also be caused to form to a certain
extent in the process itself; in place of the metallic oxides, such metallic compounds
as are decomposed at a high temperature by phosphoric acid, such as the nitrates,
sulphates, chlorides and sulphides of these metals, may also be employed.
The process may also be carried out in another way by partially neutralising a
given quantity of dilute phosphoric acid with alkali or alkali carbonate or alkaline
compounds which have an analogous effect on phosphoric acid, the respective
metallic oxides or their equivalents being afterwards added in correct proportions
and the evaporated residue heated to melting point.
The process may also be carried out by evaporating a solution of phosphoric
acid with the respective metallic compound, for instance, sulphide of antimony and
melting the residue, whereupon an insoluble vitreous body is produced; if, however,
after the decomposition of the sulphide of antimony, a sufficient quantity of alkali
be added, the same easily soluble substance is obtained as if a mixture of suitable
proportions of sodium phosphate, phosphoric acid and oxide of antimony had
been employed.
Dated this 6th day of July 1801
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.
Improvements in the Manufacture of Soluble Metallic Phosphate
Compounds.
I, CARL RASPE, of 21 Sofienstrasse, Berlin, in the Empire of Germany,
Manufacturer, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement:-
This invention relates to the manufacture of soluble phosphate compounds of
alkali metals on the one hand, and of the metals tin, copper, zinc, bismuth and
antimony, on the other hand by a melting process. These compounds have either
slightly acid or alkaline reactions and more particularly the double salts of tin,
antimony and bismuth are characterised by the great stability of their solutions in
water, as these salts are only decomposed by water either extremely slowly or not
at all. By the production of such soluble double compounds the solutions of
which in water are as stable as possible, an important technical application is
secured for the above named metals more particularly in dyeing, electro-metallurgy
and medicine.
Experiments made for this object have shown that, by melting together the
metallic oxides in question with alkali and phosphoric acid, very soluble compounds
may be obtained, if the proportions be so chosen that the resulting substance
contains not less than 1 atom of phosphorus to two atoms (monovalent) of metal
plus alkali metals. If more metallic oxide be employed, a corresponding quantity
of tri-metallic phosphate or excess metallic oxide would result. If so much
metallic oxide be employed that the metal of the same and the alkali metal of the
alkaline substance are sufficient to convert all the phosphoric acid present into
tri-metallic phosphate, only such insoluble trimetallic phosphate is produced and no
soluble metallic phosphate. If, therefore, more particularly soluble metallic.
phosphate is to be produced by this process, in no case must so much metallic
oxide plus alkali be present in the melting mixture that for every atom of
phosphorus there are three atoms of metal (monovalent) of the metallic oxide and
alkali; the highest practical limit is two atoms of metal (monovalent) of the
metallic oxide and alkali, to one, atom of phosphorus. As in practice it is.

page_text: desirable to obtain a soluble product as rich as possible in metallic oxide, the
minimum limit for the metallic oxide material must be so chosen that it still
exceeds the proportion of one atom of metal (monovalent) of the metallic oxide
and alkali, to one atom of phosphorus even although a larger quantity of phosphoric
acid does not injure the solubility.
It is practically impossible to use so little metallic oxide or so much phosphoric
acid that a double metaphosphate is produced on account of the strongly acid
character of the melting mixture before and during the melting, as the melting
vessels made of such materials as are available in practice, are not sufficiently
durable to stand such a mixture.
The process described in this invention is accordingly generally carried out by
melting metallic oxide together with alkali and phosphoric acid, the above named
limits in proportioning the quantities being retained, the result of this being a
vitreous somewhat bygroscopic substauce. The proportions of the substances in
these mixtures, which must produce clear, soluble, phosphate double compounds of
metal and alkali, are indicated in the following examples, which serve to more
particularly describe and explain this invention :-
1st. TIN AND SODIUM.
2 molecules of protoxide of tin, 1 molecule of phosphorus pentoxide and
2 molecules of sodium phosphate form even at a very slight red heat a molten mass
which has an alkaline reaction, and on the basis of the proportions of tin,
phosphorus pentoxide and sodium phosphate, may be regarded as a pure pyrophos-
phate compound. The solution of the same is precipitated both by acids and
alkalies and remains unchanged when boiled. Pyrophosphate tin-soda-compounds,
for the production of which the tin is used in the form of stannic acid and not of
protoxide of tin, are, in contrast to this above described compound mostly entirely
insoluble or only soluble in acid; for this reason they are not equal for technical
purposes to the above described protoxide of tin compound and can in no way
replace it.
2. COPPER AND SODIUM.
2 molecules of cupric oxide, 2 molecules of phosphorus pentoxide and 3 molecules
of sodium phosphate yield when heated first a soft paste which solidifies with an
increase of temperature, but becomes again liquid at a still higher température,
whilst at the same time a vigorous frothing takes place. Water is freely driven
off and after cooling there results a clear green mass soluble in water. This
solution is blue, has a slightly acid reaction and is not precipitated by acids or by
boiling but by soda lye; the compound of copper and sodium thus formed differs
essentially from the double compounds bitherto known in its capability of being
used on account of its solubility.
3. ZINC AND SODIUM.
2 molecules of oxide of zinc, 3 molecules of phosphorus pentoxide and 4 molecules
of sodium phosphate form at a high red heat when skimmed a clear molten mass
having an acid reaction, the solution of this mass behaving like that of the copper
compound. This zinc soda compound dissolves indeed only somewhat slowly but
it is far more soluble than the compounds hitherto known and in contrast thereto
is very suitable for use for certain technical and medicinal purposes.
4. ANTIMONY AND SODIUM.
2 molecules of oxide of antimony, 6 molecules of phosphorus pentoxide and.
7 molecules of sodium phosphate form even at a low red heat a clear soluble
molten mass.
On being further heated, it solidifies but afterwards becomes again
liquid. The first product yields a neutral or rather amphoteric solution which

page_text: solution of when shortly becomes turbid. The thinner such solutions are, the
more slowly they become turbid, which forms a remarkable distinction between
this improved double compound and other antimony salts. This new compound is
also non-corrosive and on account of this property is particularly suitable for certain
technical and medicinal purposes.
5. BISMUTH AND SODIUM.
1 molecule of oxide of bismuth, 2 molecules of phosphorus pentoxide and
6 molecules of sodium phosphate yield when melted a substance having an alkaline
reaction. A ten per cent. solution in water remains clear for 24 hours, a 5 per cent.
one apparently permanently. In any case such solutions are rapidly decomposed
by acids and alkalies but only slowly by boiling. As this compound as well as that
described as No. 4 is not at all corrosive, this property makes it suitable for use
for technical and medicinal purposes.
Of course the metallic oxides may not only be used when already formed, but
may also be caused to form to a certain extent in the process itself; in place of the
metallic oxides, such metallic compounds as are decomposed at a high temperature by
phosphoric acid, such as the nitrates, sulphates, chlorides and sulphides of these
metals, may also be employed.
The process may also be carried out in another way by partially neutralising a
given quantity of dilute phosphoric acid with alkali or alkali carbonate or alkaline
compounds which have an analogous effect on phosphoric acid, the respective
metallic oxides or their equivalents being afterwards added in correct proportions
and the evaporated residue heated to melting point.
The process may also be carried out by evaporating a solution of phosphoric
acid with the respective metallic compound, for instance, sulphide of antimony and
melting the residue, whereupon an insoluble vitreous body is produced; if, however,
after the decomposition of the sulphide of antimony, a sufficient quantity of alkali be
added, the sanie easily soluble substance is obtained as if a mixture of suitable
proportions of sodium phosphate, phosphoric acid and oxide of antimony had been
employed. Similarly a solution of phosphoric acid can be evaporated to dryness
with the alkali phosphate and metallic oxide and heated to the melting point.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. The improvements in the manufacture of soluble phosphate compounds of
alkali metals and tin, copper, zine, antimony and bismuth, in which compounds to
1 atom of phosphorus there is less than 3 (preferably not more than 2) monovalent
atoms of metal plus alkali metals, but more than 1 such atom, consisting in melting
together alkali, phosphoric acid and the metallic oxide in question; substantially
as herein before described.
2. A modification of the process described in Claim 1 consisting in evaporating
a solution of phosphoric acid, alkali phosphate and the respective metallic oxide,
and heating the evaporated residue to melting point.
3. A further modification of the process described in Claim 1, consisting in
partially neutralising dilute phosphoric acid with alkali or alkaline compounds,
evaporating the same and then melting it with a suitable metallic oxide.
4. In the process described in Claims 1, 2 and 3, the use of metallic oxides in
a natural condition, or the formation of the same in the actual course of the
process itself by the use of such metallic compounds of the respective metals as
are decomposed by being melted with phosphoric acid, substantially as hereinbefore
described.

page_text: 5. A new
or improved industrial product consisting of the soluble double
phosphate compounds formed by the process described in Claims 1-4 of alkali
metals with tin, copper, zine, antimony or bismuth substantially as herein before
Bet forth.
Dated this 1st day of April 1895.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.