Astringent Substances as Sources of Pyrogallic Acid. 421 
acid obtained from sumach to an excess of boiling acetate of 
lead. It precipitated as a yellow, slightly crystallme powder, 
and was also dried at 212° F. 
I. 0°803 salt gave 0°456 oxide and 0°142 metallic lead = 
75°84 per cent. oxide of lead. 
II. 0°6972 gave 0°332 oxide and 0°186 metallic lead = 76°35 
oxide. 
Now the bibasic gallate of lead C? H O? + 2 Pb O contains 
76°69 per cent. oxide of lead; therefore there can be no doubt 
that it was the salt analysed, and that gallic acid, therefore, 
occurs to a considerable extent ready formed in sumach. 
I next proceeded to examine the tannin. In order to ob- 
tain the tannin of sumach free from gallic acid, I macerated a 
very considerable quantity of sumach in a very little cold 
water, filtered the liquid, and threw down the tannin it con- 
tained by adding to the solution about half its bulk of sul- 
phuric acid by small quantities ata time. The precipitate, 
which had a brownish yellow colour, was tolerably abundant. 
It was collected on a cloth filter, washed with a little cold 
water, and strongly compressed so as to remove as much of 
the sulphuric acid as possible. It was then dried and distilled. 
It yielded crystals of pyrogallic acid as freely as the same 
uantity of tannin of galls would have done. The products 
of the distillation of tannin from both these sources are, there- 
fore, the same. 
In order to see if the analogy extended any further, 1 was 
induced to try if the tannin of sumach would be converted into 
gallic acid by being boiled with dilute sulphuric acid, as is the 
case with tannin when similarly treated. A second portion, 
therefore, of the tannin of sumach precipitated by sulphuric 
acid and purified like the former, was boiled for an hour with 
a mixture of two parts water and one of sulphuric acid. It 
was filtered while hot. When the liquid cooled, an abundant 
crop of hard, dark brown crystals appeared. ‘They were col- 
lected on a filter and washed with a little cold water, then 
pressed and dried. They were repeatedly dissolved in small 
quantities of water, and boiled with purified animal charcoal 
till they were perfectly colourless. When subjected to analysis, 
I. 0:279 acid gave 0°505 carbonic acid, and 0-945 water. 
II. 0°3145 gave 0°5675 carbonic acid, and 0:1056 water. 
L iV Calculated. 
C 50°04 49°78 7C =49'89 
H 3°76 3°73 83H= 3°49 
O 46°20 46°49 5 O = 46°62 
100°00 100°00 100°0G 
