IMPROVEMENTS IN THE PRODUCTION OF TANNIN AND CANOCARPINE
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by Paul Philippe François Micheá
at the Office of the Commissioners of Patents, with his Petition, on
23rd January 1874.
I, PAUL PHILIPPE FRANÇOIS MICHEÁ, of Wassind Factory, Tamah
District, in the Bombay Presidency, India, but at present of Nos.
17 and 18, Leadenhall Street, in the City of London, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN THE PRODUCTION
OF TANNIN AND CANOCARPINE," to be as follows:
My Invention relates to a process for the production of tannin from
tannin bearing plants, trees, fruits, leaves, barks, or extracts thereof,
such as gallnuts, sumach, oak bark, valonia, hemlock, chestnut, divi divi,
myrobolans, mimosa catechu, mimosa Australiensis, mimosa Indica,
ucaria Gambier, canocarpus latifolia, myrobolana officinalis, ptenocarpus
masurpium, butca frondosa, and the bark of the Indian terminalia; the
said process being also applicable in the production of a substance now
known in commerce as "canocarpine" for a certain process for the pro-
duction of which Letters Patent were granted to me on the 20th
September 1872. No. 2786.

page_text: According to my Invention the tannin is extracted from the said
plants, trees, or other substances by maceration or decoction, either in a
cold or hot aqueous solution of common salt; sea water is very suitable
for the purpose, but I do not limit myself to a solution of salt of the
strength of sea water.
A solution of sulphate of soda may also be used for the above purpose,
but in this case it is necessary to add thereto about one per cent. of a
soluble salt of lime or magnesia or a mixture of these. Such addition of
about one per cent. of the above-named soluble salts or mixtures thereof
may also be used with advantage when sea water or a solution of
common salt is employed, more particularly in the cases where the
solutions of tannin are very concentrated.
I do not limit myself to the above proportion of the soluble salts. By
the above means a liquid is obtained from which the greater portion of
the tannin can be precipitated by the addition of an alkali, whether
caustic or carbonated or by an alkaline earth. Potash, soda, and
ammonia, and their carbonates are well suited for this purpose, and
should be added until the liquid is slightly alkaline to test paper.
Hydrates of lime, baryta, and strontia produce similar precipitates, and
these alkaline earths or their solutions should be added until they cease
to give any further precipitate. Hydrate of magnesia and bi-carbonate of
magnesia may also be used for this purpose.
The tannin compounds precipitated by the above processes are
collected, and if thought desirable may be washed with sea water or
solutions of common salt or of sulphate of soda. These precipitatos
whether previously dried or in a moist state are then suspended by
stirring them up with water, whereupon by the gradual addition of a
free acid, preferably hydrochloric acid, or acetic acid, the precipitates aro
dissolved and a solution of tannin is obtained in a more or less con-
centrated state, according to the amount of water employed.
An excess of acid should be avoided in the above process, which may
bo easily done by not adding sufficient acid to entirely dissolve the
precipitate.
The solution obtained as above described gives all the usual reactions of
tannin, such as a black precipitate with salts of iron and the usual white
precipitate with gelatine.

page_text: In the Specification to the before-mentioned Letters Patent granted to
me I described a process of obtaining from the leaves of the canocarpus
latifolia a substance which I termed "canocarpine," which resulted from
the action of heat on the tannin of the said leaves.
According to my present Invention I produce this substance by sub-
jecting a decoction of the said leaves to fermentation until the tannin is
destroyed, which operation may occupy several weeks, during which
time the scum has to be carefully removed. I then treat this fermented
liquid by the method above described for the production of tannin,
whereby I obtain a solution of canocarpine ready for use as a dye stuff.