PART I
SECTION I

THE SYNTHESIS OF VEGETABLE TANNINS


1. TANNIN

The first investigations of gall-tannin date from the year 1770, at
which time, however, no exact differentiation between tannin and gallic
acid was made. The first step in this direction was made when
Scheele,[Footnote: Grell's _Chem. Ann._, 1787, 3, I.] in 1787,
discovered gallic acid in fermented gall extract, and in the same year
Kunzemuller [Footnote:_Ibid._, 1787,3,413.] separated gallic acid (or
pyrogallol) as a crystalline body from oak galls. Dize [Footnote:
_Jour. Chim. et Phys._, 1791, 399.] continued the investigations, which
were brought to a conclusion with Deyeux' work [Footnote: _Ann. Chim._,
1793, 17, I.]; both recognised that the substance isolated was not a
single substance, but was a mixture of gallic acid, a green colouring
matter, a rosin (tannin?), and extraneous matter. Proust [Footnote:
_Ibid._, 1799, 25, 225.] was the first to differentiate the crystalline
gallic acid from the amorphous, astringent substance, which latter he
named "Tannin."

Amongst the numerous subsequent investigations of tannin must be
especially noted the one by Berzelius [Footnote: Pogg,_Ann._, 1827, 10,