280 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, 2.660 grm. Carbonic’ 
acid and 0.512 of water. ‘This gives its composition in one hun- 
dred parts ; 
Carbon, ; A 79.079 
Hydrogen, 5 5 : 5.688 
Oxygen, ; 15.233 
consequently the same fetieni) ieponion 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 bromobenzéy], 
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 forma 
milky fluid, from which by cooling after it has been heated, thick flakes 
