282 Dr. Stenhouse on Pyrogallic Acid. 
II. 0°731 salt gave 0°252 oxide and 0°153 lead = 57:02 
oxide of lead. 
III. 0°6402 gave 0°1712 oxide and 0°1815 lead = 57:28 
per cent. oxide. | 
IV. 0°709 salt, dried at 212° F., gave 0:252 oxide and 0°143 
lead = 57°27 per cent. oxide. 
0°5685 salt gave, when burnt with oxide of copper, 0°504 
carbonic acid and 0°117 water. 
Calculated. 
C= 24°51 8C = 611°480 = 24°89 
i=" 2:28 4H= 49:918= 2:03 
O = 16°03 4 O = 400°000 = 16°30 
Pb O = 57°18 Pb O = 1394°500 = 56°78 
100°00 2455°898 100°00 
The mean of these determinations gives 1044 for the atomic 
weight of pyrogallic acid, which corresponds pretty closely 
with the calculated number 1061. It is evident also that these 
analyses give C8 H 4 O 4 as the formula of pyrogallic acid ; 
and not C, H; O,, that of Berzelius. The formula C, H, O, 
is that found by the late R. C. Campbell, as stated in Liebig’s 
Geiger; but I am not aware that the details of his analysis 
have ever been published. 
When even a single drop of caustic ammonia is added to a 
solution of pyrogallic acid, it becomes alkaline and assumes a 
dark brown colour. A great excess of ammonia was added 
to a solution of pyrogallic acid, which was then evaporated zn 
vacuo. "The acid crystallized in confused tufts of a dark 
brown colour; when pounded, however, its colour was only 
light brown. It did not give the least indication of ammonia 
when heated either with a strong solution of potash or with 
quick lime. When dried in vacuo and subjected to analysis, 
I. 04620 substance gave 0:9255 carbonic acid, and 0:201 
water. 
II. 0°3141 substance, also dried in vacuo, gave 0°6314 car- 
bonic acid, and 0°1405 water. 
I 
: Il. 
C 55°38 C 55°58 
H 4°83 H 4:96 
O 39°79 O 39°46 
100:00 100°00 
Now pyrogallate of ammonia should have given only 4444 
per cent. carbon, and 6°34 per cent. hydrogen. 
The substance of number II. was prepared at a different 
time from number I.; and in its preparation a still larger ex- 
cess of ammonia was employed. ‘The reactions of the sup- 
posed pyrogallate of ammonia with salts of iron and milk of 
