268 Researches respecting the radical of Benzoic Acid. 
The variation of the composition of benzoic acid, thus obtained, 
from that which Berzelius found by the analysis of the benzoate of 
lead, caused us at first to mistrust our own analysis. Upon nearer 
inspection however, we found it necessary to admit, that the cause of 
the difference between the two analyses should be sought in the com- 
position of the salt analyzed by Berzelius. We therefore undertook 
the analysis of the acid united to a base, and chose the benzoate of . 
silver because of the facility with which it is obtained pure and crys- 
tallized, and because the oxide of silver shews but little disposition to 
form compounds. 
Neutral nitrate of silver mixed with an alkaline benzoate in solu- 
tion, gave a thick white precipitate, which by warmth became crys- 
talline, and completely dissolved in a greater quantity of boiling wa- 
ter. By cooling the solution, oxide of silver was deposited in long 
shining crystals, which by drying under the air pump, neither lost 
their lustre, nor diminished in weight. 
By heating in a porcelain crucible, this salt melts, puffs up, and af- . 
ter the deposited charcoal is consumed, leaves very white metallic 
silver. In this manner we determined the atomic weight of the acid. 
I. 0.391 gramme of benzoate of silver left 0.184 of metallic silver. 
Il. 0.436 “ of the same gave 0.205. 
According to these numbers, the composition of the salt is, 
I. I. 
Oxid of silver, : 50.56 4 50.52 
Benzoic acid, , 49.44 ; 49.48 
And the atomic weight of the acid as the mean of both analyses, 
is 142.039. 
We now submitted the salt of silver to ignition with oxide of cop- 
per, and obtained from 0.600 grammes of the salt, 0.797 grammes of 
carbonic acid, and 0.122 of water. 
The composition of the acid, as deduced {rom these numbers, con- 
sists in 100 parts of 
Carbon, é ; : 74.378 
Hydrogen, d j : 4.507 
Oxygen, : : : 21.055 
Calculating from the atomic weight already found, we obtain, 
14: atomerearbon lh OS “LOTONTE PFA AS 
10)" Chydiropens 7) 2 OLDaO TN 4.34 
366) @xyeen, ‘ SOL000) Tanne Tees 
143.2515 100.00 
