Researches respecting the radical of Benzoic Acid. 269 



By comparing (he analysis of the crystallized acid with that com- 

 bined with the oxide of silver, it is at once evident that the difference 

 between them is that the former contains one atom of water, which 

 is wanting in the latter. 



The only difference then between the analysis of Berzelius and 

 our own, lies in this content of water. For from the atomic weight 

 found by Berzelius, as well as from the behavior of the oxide of lead, 

 it follows that the oxide by union with benzoic acid, does not separate 

 ihe water of the same, but that this water enters into the composition 

 of the salt. On being heated, and especially in the crystallized state, 

 when, as we have just seen, it contains one atom of water, it loses a 

 portion of its acidity. 



In fact, if from the atomic weight of benzoic acid, as obtained by 

 Berzelius from the oxide of lead, namely, . 152.1423 



We take off one atom of water, . . 1 1.2479 



We get for the atomic weight of the dry acid, 140.8944. 



If according to this corrected atomic weight, we calculate the car- 

 bon and hydrogen of Berzelius' analysis, we likewise obtain 14 atoms 

 of carbon and 10 of hydrogen. 



These comparisons will suffice to remove every doubt respecting 

 the composition of benzoic acid and the statement of Dumas, that 

 this acid contains hydrogen and oxygen in the same proportion as 

 water, is certainly an error, which he will undoubtedly correct. 



Returning from this digression to the consideration of the oil of 

 bitter almonds, and its conversion into crystallized benzoic acid, we 

 now find this phenomenon capable of an easy explanation. The 

 acid is formed by simple oxydation, the oil absorbing in the air or in 

 oxygen gas, 2 atoms of this element. 



The formation of benzoate of potassa from the oil, when the latter 

 is heated with hydrate of potassa, depends upon the decomposition 

 of the water in the hydrate, whereby the oil takes one atom of oxy- 

 gen, while hydrogen escapes in the form of gas. 



We have farther mentioned that the oil with a solution of potassa 

 in alcohol, forms likewise without the access of air a benzoate of 

 potassa, and that then by the addition of water, an oily body sepa- 

 rates from the alcohol possessed of different properties. As far as 

 we have examined this new body, it admits of no doubt, that in case 

 the constituents of alcohol do not enter into its composition, it origi- 

 nates either form taking oxygen from the bitter almond oil, or from 



