and some of the Astringent Substances which yield it. 281 
of pyrogallic acid bright red and then blackens them. Moist 
chlorine, when sent through a solution of pyrogallic acid, gives 
it a hyacinth-red colour, and evolves much muriatic acid ; no 
precipitate fell, however, and when left to spontaneous evapo- 
ration it yielded no crystals, but left only a reddish gummy 
mass. Pyrogallic acid reduces the oxides of gold, silver and 
platinum to the metallic state, and precipitates them com- 
pletely from their solutions. In order to test the purity of 
the pyrogallic acid I had obtained, it was dried at 219° F ts 
and analysed in the usual way. 0°312 gram. gave 0°65 car- 
bonic acid, and 0°1345 water. 
Found. Calculated. 
C 57:60 C 8=611+480 = 57°61 
H 478 H4= 49:9918= 470 
O 37°62 O 4=400:000 = 37°69 
100°00 1061°398 100-00 
This result agrees closely with the calculated numbers 
given above. 
I next endeavoured to form the hydrate of pyrogallic acid 
by dissolving some very pure crystals in a small quantity of 
water, and evaporating the solution zm vacuo over sulphuric 
acid. It gave large white needles of a silky lustre. 
Burnt with oxide of copper,— 
I. 0°3265 gramme substance, dried in vacuo, gave 0°68 car- 
bonic acid, and 0°138 water. 
II. 0°2873 gramme, dried at 212° F., gave 0°600 carbonic 
acid, and 0°124 water. 
I. fe Calculated. 
C 57°58 57°83 57°61 
H 4°97 4°79 4°70 
O 37°45 37°38 37°69 
100°00 100-00 100°00 
Pyrogallic acid, therefore, does not form a hydrate. 
Pyrogallate of Lead. 
In order to determine the atomic weight of pyrogallic acid, 
the lead salt was prepared by adding a solution of pyrogallic 
acid to an excess of neutral acetate of lead inthe cold. A co- 
pious white flocculent precipitate immediately fell. It was 
washed repeatedly by decantation, then thrown upon a filter 
and rapidly washed, the air being excluded as much as pos- 
sible, and when pressed between folds of blotting-paper was 
dried in vacuo. When dried it was still nearly white, having 
only a slight shade of yellow. 
I. 0°7985 gramme, dried in vacuo, gave 0'269 oxide of lead 
and 0°174 metallic lead = 57°16 per cent. oxide. 
