56 
THE TANNINS. 
parts of the world. Poorer varieties are shipped from 
some other Mediterranean ports. 
Galls are nearly globular, from ten to twenty milli¬ 
metres in diameter, tapering slightly towards the base, 
the lower half being smooth, while the upper portion 
is usually covered with numerous bluntly-pointed tu- 
bercules. The best galls are gathered before the insect 
has matured; if left until after this development has 
occurred, there is found about half-way between the 
stem and summit a small hole, from which the devel¬ 
oped insect has escaped; at this period they are found 
to be deficient in tannin, and therefore become the green 
or white variety. Those collected at the proper time 
are heavy, somewhat brittle, breaking with a slightly 
resinous fracture, exhibiting the larva in a small cavity 
at the centre, while the surrounding tissue frequently 
appears as a radiating structure. Internally galls are 
deep greenish yellow, without odor, of a slightly acid 
and very astringent taste with a faintly sweetish after¬ 
taste. 
When Scheele in 1786 discovered gallic acid he sup¬ 
posed it to be the most important constituent; Chevreul 
afterwards found ellagic acid; then Scheele produced 
pyrogallic acid, and supposed it identical with > gallic 
acid, but much purer, on account of having been sub¬ 
limed ; then followed the work of Dize, Deyeux, Se- 
guin, and Proust, as stated in the preceding general 
history. 
After the existence of tannic acid was well estab¬ 
lished, Davy in 1803 appears to have been the first 
to make an analysis of nutgalls, with the following 
result: 
