IMPROVEMENTS IN THE MANUFACTURE AND PREPARATION OF TANNIC ACID
Year: 1880

page_text: LETTERS PATENT to Ferdinand August Zimmermann, of No. 21, Mincing Lane,
in the City of London, Commission Agent, for an Invention of "IMPROVEMENTS
IN THE MANUFACTURE AND PREPARATION OF TANNIC ACID." A communica-
tion from abroad by Ernst Schering, Managing Director of the Chemische
Fabrik auf Actien, of Berlin, Germany.
PROVISIONAL SPECIFICATION left by the said Ferdinand August Zimmer-
mann at the Office of the Commissioners of Patents on the 13th January 1880.
FERDINAND AUGUST ZIMMERMANN, of No. 21, Mincing Lane, in the City of
London, Commission Agent. "IMPROVEMENTS IN THE MANUFACTURE AND PREPA-
RATION OF TANNIC ACID." A communication from abroad by Ernst Schering,
Managing Director of the Chemische Fabrik auf Actien, of Berlin, Germany.
Tannic acid for various technical purposes, such as for use in dyeing operations,
has hitherto been usually manufactured by heating the solution of tannin at a high
temperature, and so desiccating it more or less. A residuum consisting of tannic
acid is in this way obtained which is of a tough character, and is usually afterwards
ground into a powder, in which form it is generally sold as a commercial article for
the purposes above referred to. This process of desiccating the tannin solution at a
high temperature, and pulverising the desiccated residuum, is attended with many
disadvantages. The contact of the air causes a partial transformation of the tannin
into gallic acid; the pulverised desiccated substance is in many cases inconvenient
for use, and the character of the tannic acid so manufactured or prepared is wanting
in purity and is otherwise injuriously affected.
This will be manifest from an examination of the aqueous solution of such tannic
acid, as it will never be perfectly clear. Again, the tannic acid in powder form readily
absorbs moisture when used in the form of solution; it lumps together and dissolves
then very slowly and with difficulty. Even perfectly dry tannic acid powder, when
brought into water, forms often thick lumps which render solution difficult.
By the present improved process of manufacture and preparation these difficulties
are obviated; in fact, a new form of tannic acid is produced which is for technical
purposes a much better product than the powder prepared in the old way, and is an

page_text: improved product which the consumer will find to be much superior to the tannic
acid in powder as hitherto made as regards purity, and stability.
To manufacture the improved tannic acid,-
The thick extract or solution of tannin (whether it be combined with water,
alcohol, or ether) is placed in a heated chamber or vessel whose heat is regulated
and maintained at a low temperature, and from which access of air is excluded as
much as possible; the extract or solution is thus slowly evaporated until it is
reduced to a thick or pasty condition. It is then forced by a pressing apparatus
through a plate perforated with small holes, from which it exudes in thin filaments
like thin vermicelli threads; these are wound as they exude on suitable reels or
cylinders, or they may be collected in any convenient manner.
The threads so obtained, on cooling, will be found to be very brittle, and will
break up into golden, shining, needle-like fragments, which can be readily collected
and preserved in bottles or other convenient receptacles.
The improved tannic manufactured by the improved process above described
acquires its crystal needle-like form and bright shining appearance in consequence
of the glass like character of the surface of the threads. It does not absorb moisture,
it does not lump together, while it dissolves freely and is not liable to oxydation.
In use for the purposes for which tannic acid is used, especially in dyeing opera-
tions, it will be found very superior to tannic acid manufactured and prepared in
the old way.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Ferdinand August Zimmermann in the Great Seal Patent Office on
the 13th July 1880.
FERDINAND AUGUST ZIMMERMANN, of No. 21, Mincing Lane, in the City of
London, Commission Agent. "IMPROVEMENTS IN THE MANUFACTURE AND PREPA-
RATION OF TANNIC ACID." A communication from abroad by Ernst Schering,
Managing Director of the Chemische Fabrik auf Actien, of Berlin, Germany.
Tannic acid for various technical purposes, such as for use in dyeing operations
has hitherto been usually manufactured by heating the solution of tannin at a high
temperature, and so desiccating it more or less. A residuum consisting of tannic
acid is in this way obtained which is of a tough character and is usually afterwards
ground into a powder, in which form it is generally sold as a commercial article for
the purposes above referred to.
This process of desiccating the tannin solution at a high temperature and pul-
verising the desiccated residuum is attended with many disadvantages. The contact
of the air causes a partial transformation of the tannin into gallic acid, the pulverised
desiccated substance is in many cases inconvenient for use, and the character of the
tannic acid so manufactured or prepared is wanting in purity and is otherwise
injuriously affected.
This will be manifest from an examination of the aqueous solution of such tannic
acid, as it will never be perfectly clear. Again, the tannic acid in powder form
readily absorbes moisture when used in the form of solution; it lumps together and
dissolves then very slowly and with difficulty. Even perfectly dry tannic acid
powder, when brought into water, forms often thick lumps, which render solution
difficult.
By the present improved process of manufacture and preparation these difficulties
are obviated; in fact, a new form of tannic acid is produced which is for technical
purposes a much better product than the powder prepared in the old way, and is
an improved product which the consumer will find to be much superior to the
tannic acid in powder as hitherto made as regards purity and stability.
To manufacture the improved tannic acid the thick extract or solution of tannin
(whether it be combined with water, alcohol, or ether) is placed in a heated chamber
or vessel whose heat is regulated and maintained at a low temperature, and from
which access of air is excluded as much as possible; the extract or solution is thus
slowly evaporated until it is reduced to a thick or pasty and unsticky condition.
It is then passed through a plate perforated with small holes, from which it exudes
in thin filaments like thin vermicelli threads; these are wound as they exude on
suitable reels or cylinders, or they may be collected in any convenient manner.
The threads so obtained on cooling will be found to be very brittle, and will break
up into needle-like fragments, which can be readily collected and preserved in
bottles or other convenient receptacles.
The improved tannic manufactured by the improved process above described
acquires a crystal needle-like form. In consequence of the glass like character of
the surface of the threads it does not absorb moisture, it does not lump together,
while it dissolves freely and is not liable to oxydation.
In use for the purposes for which tannic acid is used, especially in dyeing opera-
tions, it will be found very superior to tannic acid manufactured and prepared in
the old way.
Having now described the nature of the said Invention, and in what manner the
same is to be performed, I declare that I claim,-
The particular treatment of ordinary thick extract or solution of tannin for the
manufacture or preparation of tannic acid therefrom, as described.

page_text: Secondly. I claim the manufacture of tannic acid in crystal needle like form from
thick extract or solution of tannin, by the method or means herein before described.
In witness whereof, I, the said Ferdinand August Zimmermann, have hereunto
set my hand and seal, this Twelfth day of July, in the year of our Lord One
thousand eight hundred and eighty.
FERDINAND AUGUST ZIMMERMANN. (L.S.)