2S0 Researches respecting the radical of Benzoic Acid. 



from the fact, as analysis proves, that it has a perfectly similar com- 

 position, and is therefore an isometric modification of the same, as is 

 apparently shewn by its unintelligible origin from the oil, through the 

 equally inexplicable action of potassa, but from the access of air. 



1.00 grm. of benzoin yielded by ignition, 2.860 grrn. Carbonic 

 acid and 0.512 of water. This gives its composition in one hun- 

 dred parts ; •-.-.•-•--. 



Carbon, 



Hydrogen, 



Oxygen, 



79.079 



5.683 



15.233 



consequently the same (atomic) proportion of the same elements as 

 in hydrobenzoyl. ' 



It is indeed imaginable that the very different properties of ben- 

 zoin and hydrobenzoyl arise from the manner of the hydrogen's 

 combination, which in the first may be united to one atom of ox- 

 ygen as water. But, as this difference depends on such a very diffe- 

 rent manner of the hydrogen's combination, the idea, that the hydro- 

 gen, can no longer as in the oil, be replaced by another body, as chlo- 

 rine, seems to be refused by the behavior of benzoin to bromine. 



Thus if bromine be poured over it, it becomes heated and boiling 

 and evolves hydrobromic acid in abundance. After this acid and 

 the surplus of bromine are expelled by heat, the benzoin will be 

 found changed to a brown viscous fluid, smelling like bromobenzoyl, 

 but unlike the latter it is soft. With boiling water it appears to be 

 decomposed either not at all or exceedingly slowly. With caustic 

 potassa, it is indeed decomposed by boiling, but even then with diffi- 

 culty. The alkaline solution mingled with hydrochloric acid depos- 

 ites fine needle-form crystals, which do not appear to be benzoic 

 acid, nor can they be unchanged benzoin, since they readily dis- 

 solve in alkali. Could we consider the above mentioned bromoben- 

 zoin, as an isometrical modification of the corresponding benzoyl 

 compound, then were it imaginable that a new acid had formed by 

 the above decomposition with alkali, which might be an isometric 

 modification of benzoic acid. 



We in vain endeavored to reconvert benzoin into hydrobenzoyl. 

 Fused with hydrate of potassa, it changes like the oil into benzoic 

 acid, with the evolution of hydrogen. But again it differs from the 

 oil, in its behavior with a solution of potassa in alcohol. It is dissolved 

 in the alkaline solution with a purple color, and presently the whole 

 congeals to a mass of fine, foliated crystals. With water these form a 

 milky fluid, from which by cooling after it has been heated, thick flakes 



