properties which could hardly be ascribed to tannin. Lloyd [Footnote:
_Chemical News_, 1908, 97, 133.] proposed a very intricate formula
containing three digallic acid groups joined into one six-ring system,
which would then explain the optical activity; it would, on the other
hand, also require an inactive cis-form.

Iljin [Footnote: _Jour. of the Russian phys. chem. Soc._, 1908, 39,
470.] prepared two phenylhydrazine derivatives of tannin (C_74 H_58 N_8
O_30 and C_98 H_82 N_14 O_96) and proposed the formula, C_58 H_40 O_33,
the constitution of which would be--

R_1 R_1
| |
}C--O--O--C{
| | |
R_2 | R_2
O
R_1 | R_1
| | |
}C--O--O--C{
| |
R_2 R_2

where R1= CO C_6 H_2 (OH)_3
and R2= C_6 H_2 (OH)_2

Nierenstein [Footnote: _Ber._, 1905, 38, 3841; 1907, 40, 917; 1908, 41,
77 and 3015; 1909, 42, 1122 and 3552; _Chem. Ztg._, 1907, 31, 72; 1909,
34, 15.] considers tannin to be a mixture of digallic acid and
leucotannin, the latter possessing the formula--