70 
THE TANNINS. 
I. II. III. IV. 
C. 51.77 51.56 51.20 51.72 
H. 3.98 4.37 4.29 4.17 
O. 44.25 44.07 44.51 44.11 
100.00 100.00 100.00 100.00 
These figures, lie stated, closely agreed with those 
obtained by Berzelius and indicated the formula 
Ci 8 H 18 0 12 . 
The remainder of the memoir was devoted to show¬ 
ing the acid properties of the tannin and its capability 
to form definite salts with the different bases. He 
further stated that gallic acid did not pre-exist in the 
galls, but that it was a product of atmospheric action 
on tannin, that at a temperature of 215° it was trans¬ 
formed into pyrogallic acid and carbon dioxide, and 
that pyrogallic acid in turn was converted into meta¬ 
gallic acid and water. This appears to have been the 
first statement, based on experiment, that tannin be¬ 
comes converted into gallic acid through the influence 
of atmospheric oxygen. 
This work of Pelouze attracted general attention to 
the subject, and in the same year Liebig published his 
results on an elementary analysis in which he found: 
C. 52.50 
H. 4.12 
O. 43.38 
100.00 
and concluded that C 18 H 16 0 12 more closely represented 
the formula. This he communicated to Pelouze, who 
undertook anew the analysis, obtaining the following 
percentage composition : 
