74 
THE TANNINS. 
no better method of preparing the acid had since been 
discovered. 
After further reviewing the work of Pelouze on py- 
rogallic and melangallic (metagallic) acids, he studied 
the conversion of tannic into gallic acid by the action 
of other acids; the action of alkalies on tannic, gallic, 
and ellagic acids; the percentage composition of tannic 
acid and its formula; the action of ammonia; and, 
finally, some of the tannates, especially of lead. 
With the exception of the work done by Liebig, it 
is safe to say that this work of Mulder was the most 
elaborate investigation after that of Pelouze, which in 
many respects it resembled. 
While there were about the year 1850 a number of 
creditable publications, nothing is of great historical 
value until we reach the work of Strecker in 1852 and 
1854, which he carried out in Liebig’s laboratory. 
These contributions are among the few that stand out 
prominently, for, besides reviewing some of the work 
of others, he detected the presence of sugar, as had been 
previously indicated in Liebig’s revision of Geiger’s 
Handbuch der Pharmacie, edition of 1843, page 854, 
where it is stated that Braconnot found in the fermen¬ 
tation of galls alcohol and carbon dioxide, which in¬ 
dicated the presence of sugar, that had not been pre¬ 
viously noted, and that tannic acid contained “the 
elements of six atoms of gallic acid and one atom of 
grape-sugar.” Strecker had noticed that by heating 
tannic acid carefully a large carbon residue was ob¬ 
tained, when it had been previously supposed that the 
only decomposition products were pyrogallic acid and 
carbon dioxide. He also obtained the reactions for 
