A PROCESS OF TREATING TANNIC EXTRACTS OR JUICES
Year: 1885

page_text: I JOHN CLAYTON MEWBURN, of 169 Fleet Street, in the City of London, Fellow
of the Institute of Patent Agents do hereby declare the nature of my invention
for "A PROCESS OF TREATING TANNIC EXTRACTS OR JUICES" to be as follows:-
This invention consists of a process of treating tannic extracts or juices in order
to decolorize and purify them.
According to this process the tannic juices such as are obtained by decoction
from woods or other substances by the usual methods are treated with carbonate of
lead in the proportion of about two Kilogrammes to 1000 litres of juice.. The
mixture having been effected as perfectly as possible a weight of sulphate of lead
double that of the carbonate of lead employed is added... The mixture is left at
rest and is filtered if necessary. The extract is then concentrated to the desired
degree.
In this operation the coloring matters and the acid resins of the woods or other
substances from which the tannic juices have been obtained, unite with the lead,
displacing the carbonic acid which is disengaged, and are rendered insoluble as well
as a small quantity of tannic acid.
-
The action is thus double; there are decoloration and purification due to the
precipitation of the resins.
The operation can be completed by filtration effected in any suitable manner
such for example as by turbines or centrifugal hydro-extractors or filter presses.
Dated this 27th day of Angust 1885

page_text: A Process of Treating Tannic Extracts or Juices.
I JOHN CLAYTON MEWBURN, of 169 Fleet Street, in the City of London, Fellow
of the Institute of Patent Agents, do hereby declare the nature of this inven-
tion (a communication from abroad by the firm of J. Marchal et L. Bories of
1 Boulevard St Denis, Paris, France, Manufacturers) and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement:―
This invention consists of a process of treating tannic extracts or juices in order
to decolorize and purify them.
According to this process the tannic juices, such as are obtained by decoction
from woods or other substances by the usual methods, are treated with carbonate
of lead in the proportion of about two Kilogrammes to 1000 litres of juice. The
mixture having been effected as perfectly as possible an amount of sulphate of lead
double the weight of the carbonate of lead employed is added. The mixture is left
at rest and is filtered if necessary. The extract is then concentrated to the desired
degree.
In this operation the coloring matters and the acid resins of the woods or other
substances from which the tannic juices have been, obtained unite with the lead,
displacing the carbonic acid which is disengaged, and are rendered insoluble as well
as a small quantity of tannic acid.
The action is thus double; there are decoloration and purification due to the
precipitation of the resins. The added sulphate of lead acts by inducing the
precipitate and accelerating the clarification.
The operation can be completed by filtration effected in any suitable manner,
such, for example, as by turbines or centrifugal hydro-extractors or filter presses.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, as communicated to
me, I declare that what I claim is:-
The process herein before described of treating tannic extracts or juices.
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