IMPROVEMENTS IN THE MANUFACTURE OF TARTARIC ACID
Year: 1878

page_text: LETTERS PATENT to Frank Wirth, of the Firm of Wirth and Company, Patent
Solicitors, at Frankfort-on-the-Main, in the Empire of Germany, for the Inven-
tion of "IMPROVEMENTS IN THE MANUFACTURE OF TARTARIC ACID." A com-
munication from Franz Dietrich, Chemist, of Murten (Switzerland).
Sealed the 1st October 1878, and dated the 6th April 1878.
PROVISIONAL SPECIFICATION left by the said Frank Wirth at the Office of
the Commissioners of Patents on the 6th April 1878.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at
Frankfort-on-the-Main, in the Empire of Germany. "1MPROVEMENTS IN THE MANU-
FACTURE OF TARTARIC ACID." [A communication from Franz Dietrich, Chemist, of
Murten (Switzerland).]
This Invention relates to improvements in the manufacture of tartaric acid, and
is carried into effect as follows, that is to say:-
If tartar (bitartrate of potassium) and chalk (carbonate of lime) mixed with a
proper quantity of water, and in proper proportions, act upon each other in closed
vessels, carbonic acid is given off, which causes a certain pressure on the mixture
not being able to escape. By the aid of this pressure these substances are decom-
posed as follows, that is to say :-
CH KO-1881 bitartrate of potash = C'H' Ca O-1880 tartrate of lime.
Ca C08
100.0 carbonate of lime
COS
1001
288.1
288.1
When the re-action terminates, a precipitate of tartrate of lime and a solution of
bicarbonate of potash are formed; these are separated by means of any of the
known methods. The tartrate of lime is used for the manufacture of tartaric acid,
O and the solution of bicarbonate of potash is worked up in the ordinary manner.

page_text: 476-2
476.2
The neutral tartrate is now dissolved; the carbonic acid prevented from escaping
'is also dissolved under a pressure proportionate to the size of the vessel and the
quantity of the substances which have undergone the re-action. By these means
carbonate of lime is dissolved with facility, and there is obtained a solution of bicar-
bonate of lime, which is transformed together with the neutral tartrate of potassa
according to formula (e), namely:-
c) CHK206-226-2 neutral tartrate of potassn=C'H' Ca 0-1880 uentral tartrate of lime.
C₁ CO³ -1000 carbonate of lime
2K H CO³ 200-2 bicarbonate of potassa.
0:08
44.0 carbonic acid

page_text: potassa. The pressure, which at the commencement is rather low, is elevated with
the energy of the action up to a maximum, is again lowered, and disappears at the
end of the operation.
It is a special peculiarity of my process that the carbonic acid required for the
decomposition is developed by the mixed matters themselves, and out of the same;
and furthermore, that the mechanical labor necessary for getting the mixture under
pressure is furnished without expense by this same carbonic acid. This is the
theoretical base of my Invention.
In carrying the said Invention into practice the best effects are obtained if the
raw materials treated are in a finely divided state, therefore the tartar and chalk
should be previously finely ground. Rather more than is absolutely necessary of
the carbonate of lime should be employed, and it may be replaced by other suitable
carbonates.
A low degree of pressure is sufficient for carrying out the operation, but a higher
pressure should be employed in order that the work may go on more rapidly. High
pressure hastens the re-action. The pressure may be regulated by the volume of
the vessels employed. If, for instance, in a vessel of about 4,500 litres capacity are
treated,―
000 crystallzcu v LONG
1,001 bicarbonate of potassa} solution 1:5.
5,000 water
8,601
In consequence I prefer to conduct the operation in as small a space as possible in
order to obtain a pressure as high as possible.
As mixing vessels the well-known apparatus used in the manufacture of aërated
waters can be employed, with the modification that the openings for filling in the
substances and for getting out the mixture must be wider, and the stirring apparatus
must be of greater strength.
The apparatus is provided with a pressure gauge and safety valve, and is con-
nected with a conduit pipe for carbonic acid.
The substances are rapidly filled in, the apparatus closed, the stirrer moved, and
the operation may be observed by means of the pressure gauge.
If all pressure has disappeared, carbonic acid is to be pumped in. As by the
mixture and the filling in of the matters a small quantity of carbonic acid is lost,
and also neutral tartrates (generated by the decomposition) may be present in the
raw material, and as the re-action can only be terminated if there is a sufficient
quantity of carbonic acid for converting the whole quantity of potassa into bicar-
bonate, this addition of carbonic acid is indispensable. In consequence carbonic
acid is pumped in until the pressure in the apparatus has become constant, and no
carbonic acid is furthermore confined.
It is not necessary to defer pumping in carbonic acid until all pressure has dis-
appeared, but the pumping in can be begun if the indicator of the pressure gauge
continues to fall.
The addition of carbonic acid is stopped if the pressure has become constant, at
which moment the operation is terminated.
The freely developed carbonic acid is blown off, or the pressure of the same is
used for transferring the contents of the vessel to other rooms.
The apparatus is emptied and the mixture separated in any known manner.
A precipitate of tartrate of lime and a solution of bicarbonate of potassa aro
obtained. The precipitate is washed and then transferred for the manufacture of

page_text: tartaric acid. The washing water still contains a certain quantity of bicarbonate of
potassa, and in order that this carbonate may also be obtained the said water is
used in a further operation in lieu of pure water.
The solution of bicarbonate of potassa is evaporated in the well-known manner.
The small quantity of carbonic acid wanted for the work is to be borne in mind
during the evaporation of the lies of bicarbonate. As for every atom of tartar one
atom of carbonic acid is developed, the greater part of this gas remains for any
desired use.
Upon the saine principle neutral tartrates of alkali may be decomposed, and the
mother lies of the manufacture may be used.
Neutral tartrate together with carbonate of lime and carbonic acid under pressure
furnishes tartrate of limo and bicarbonate. In this case the whole intermediate
carbonic acid is of course taken from outside, and the operation must take placo
under a strong pressure of from 5 to 10 atmospheres, more or less, if the decom-
position shall be terminated within a suitable time. Without such pressure the
decomposition of the neutral tartrates cannot be effected.
Having thus fully described my said Invention, and the manner in which the
same is to be carried into practice, I wish it understood that I do not confine myself
to the exact details and proportions as above specified, but I claim, the improve-
ments in the manufacture of tartaric acid wherein I obtain carbonates of potash by
decomposing bitartrate of potassa with carbonate of lime or other suitable car-
bonates and water in closed vessels and under a pressure of carbonic acid gas, and
wherein I obtain alkaline carbonates by decomposing solutions of neutral alkalino
tartrates with carbonate of lime or other suitable carbonates and carbonic acid gas
under a pressure of about from 5 to 10 atmospheres, more or less, in the manner
substantially as above described.
In witness whereof, I, the said Frank Wirth, have hereunto set my hand and
seal, this Third day of October, in the year of our Lord One thousand eight
hundred and seventy-eight.