IMPROVEMENTS IN THE MANUFACTURE OF CREAM OF TARTAR
Year: 1884

page_text: I FRANK WIRTH, of the firm of Wirth and Company, Patent Solicitors at
Frankfort-on-the-Main, in the Empire of Germany, do hereby declare the nature
of the said invention for "IMPROVEMENTS IN THE MANUFACTURE OF CREAM OF
TARTAR" (A communication to me from Franz Dietrich, Chemist a person resident
at Munich in the Empire of Germany) to be as follows:-
The object of this Invention is the production of Cream of Tartar of the best
quality directly from Crude Tartar or Argol. The Invention is based upon the
fact that iron and alumina are always present in Argols which prevent the
production of good cream of Tartar, and are the chief cause of the loss in
manufacture and that these bodies are precipitated and removed in the form of
phosphates of iron and alumina by treating the Argols in solution with phosphoric
acid or its compounds. This precipitation and removal of phosphates goes on
partly in the hot and partly in the cooled solution.
The precipitation is not complete but fully sufficient for the success of this
process. The invention thus essentially consists in carrying on all operations
which are necessary for the transformation of crude Tartar or Argol into cream of
Tartar, in the presence of certain large amount of phosphoric acid or of any suitable
phosphate or of a mixture thereof.
I operate in the following manner. The argols are dissolved as usual in water
or mother lye; to this solution is added about 15° more or less (of the weight of
the argols) of phosphoric acid (anhydrous) or more in proportion of phosphoric
acid in solution; the whole is then boiled until all the tartar is dissolved. The
liquid is now cleared with pipe-clay or any other clarifying Agent which produces
no decomposition of the bitartrate, the hot solution is then placed in another vessel
and decolourised with animal charcoal which has been purified with muriatic acid
or in any other suitable manner; any other decolorising substance however can be
used provided it does not cause decomposition of the bitartrate.
In place of the foregoing, the solution of Argols can be first decolourised with
animal charcoal then cleared with pipe-clay and the clear hot fluid placed in
another vessel. Then the solution is cleared again with pipe clay or any other
suitable clarifying Agent, in order to precipitate the last traces of charcoal dust
Paine

page_text: and other impurities; lastly the whole is mixed with a very small amount 1-1%
more or less (of the weight of the argols) of yellow prussiate of potash in order
to remove the very small traces of copper, iron and other bodies which can thus be
precipitated.
This being done the solution is left undisturbed for clearing and drawn off for
crystallisation. In this manner cream of Tartar of the best quality is produced
in large bright, colourless crystals, in most cases a so called chemically pure
product as the tartrate of lime of the crude argols separates its self and is found as
residue. A quantity of the phosphoric acid contained in the mother lye is
consumed by the formation of phosphate, this quantity corresponds exactly with
the amount of precipitated oxides of iron and alumina.
The quantity of phosphoric acid is therefore continually diminishing as the
mother lye, as is well known, is used over and over again. It is therefore
necessary to examine the mother lye from time to time and to replace the
phosphoric acid which has been consumed. At the same time a general purification
of the mother lye is undertaken, by mixing at the same time the cold mother lye
containing phosphoric acid with an indeterminate but very small quantity of
yellow prussiate of potash in solution...
In presence of the phosphoric acid a precipitate is thus produced which chiefly
consists of unknown bodies which occur in the crude tartar and the raw materials,
and which are very unfavorable to the manufacture of cream of tartar.

page_text: I, FRANK WIRTH, of the firm of Wirth and Company, Patent Solicitors, at
Frankfort-on-the-Main, in the Empire of Germany, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF CREAM OF
TARTAR," a communication to me by Franz Dietrich, Chemist, a person resident
at Munich, in the Empire of Germany, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
The object of this Invention is the production of cream of tartar of the best
quality directly from crude tartar or argol.
The Invention is based upon the fact that iron and alumina are always present.
in argols, which prevent the production of good cream of tartar, and are the chief
cause of the loss in manufacture, and that these bodies are precipitated and
removed in the form of phosphates of iron and alumina by treating the argols in
solution with phosphoric acid or its compounds.
This precipitation and removal of phosphates goes on partly in the hot and
partly in the cooled solution. The precipitation is not complete, but fully sufficient
for the success of my process.
The Invention thus chiefly consists in all operations which are necessary for the
transformation of crude tartar or argol into cream of tartar being carried on in
the presence of certain large amount of phosphoric acid, or of any suitable
phosphate, or of a mixture thereof.
I operate in the following manner :-
The argols are dissolved, as usual, in water or mother-lye. To this solution is
added about fifteen per cent, more or less, (of the weight of the argols,) of
phosphoric acid, (anhydrous) or more in proportion of phosphoric acid in solution.
The whole is then boiled until all the tartar is dissolved. Hereupon the liquid
is cleared with pipe clay, or any other clearing substance which produces no
decomposition of the bitartrate, or by filtration alone. The hot solution is then
placed in another vessel and decolorized with animal charcoal which has been
purified with muriatic acid or in any other suitable manner. Any other decolorizing
substance, however, can be used, provided it does not cause decomposition of the
bitartrate. In place of the foregoing the solution of argols can be first decolorized
with animal charcoal, then cleared with pipe-clay, and the clear hot fluid placed in
another vessel. Then the solution is cleared again with pipe-clay or any other
suitable clearing substance, in order to precipitate the last traces of charcoal dust.
and other impurities. Lastly the whole is mixed with a very small amount,
one-half to one per cent., more or less, (of the weight of the argols) of yellow
prussiate of potash, in order to remove the very small traces of copper, iron, and
other bodies, which can thus be precipitated. This being done, the solution is left
undisturbed for clearing and drawn off for crystallization. In this manner cream
of tartar of the best quality is produced in large, bright, colourless crystals, in most
cases a so-called "chemically pure" product, as the tartrate of lime out of the argols
separates for itself, and is found as residue. A quantity of the phosphoric acid
contained in the mother-lye is consumed by the formation of phosphates. This
quantity corresponds exactly with the amount of precipitated oxides of iron and
alumina.
The quantity of phosphoric acid is therefrom continually diminishing, as the
mother-lye, as it is well known, is used over and over again. It is therefore
necessary to examine the mother-lye from time to time and to replace the

page_text: phosphoric acid which has been consumed. At the same time a general purification
of the mother-lye is undertaken, by mixing at the same time the cold mother-lye
containing phosphoric acid with an indeterminate but very small quantity of
yellow prussiate of potash in solution. In presence of the phosphoric acid a
precipitate is thus produced which chiefly consists of unknown bodies, which occur
in the crude tartar and the raw materials, and which are very unfavorable to the
manufacture of cream of tartar.
Having now particularly described and ascertained the nature of the said
Invention, and in what manner the same is to be performed, I declare that what
I claim is :-
1st The process herein described of manufacturing cream of tartar from argols,
consisting in treating the dissolved argols with phosphoric acid or its compounds
and then clarifying and decolorizing it, as set forth.
2nd The method herein described of manufacturing cream of tartar from argols,
consisting in treating the dissolved argols with phosphoric acid or its compounds,
boiling the mixture, clarifying it with clay, or otherwise, and finally decolorizing
it with animal charcoal which has been previously treated with muriatic acid, as
set forth.