1874.] Coniferine and its Conversion. 399 



tical with the crystalline substance which constitutes the aroma of vanilla, 

 and which is often seen covering the surface of vanilla-rods. 

 On analysis, the crystals we obtained were found to contain 



C 8 H 9 3 . 



This is exactly the composition which recent researches of Carles have 

 established for the aromatic principle of vanilla. The transformation of 

 the crystalline product of fermentation into vanilline is represented by 

 the following equation : 



C 10 H 12 3 + = 0,5,0 + 0.^0,. 



To remove all doubt regarding the identity of artificial vanilline with 

 the natural compound, we have transformed the former into a series of 

 salts which have the general formula 



C 8 H 7 M0 3 , 



and into two substitution-products, 



C 8 H,Br0 3 

 and 



C 8 H 7 IO S , 



both of which had previously been prepared by Carles from the natural 

 compound. 



In order further to elucidate the nature of vanilline, we have submitted 

 this body to fusion with alkali. The product of this action is a well- 

 known acid discovered by Strecker, and described by him as proto- 

 catechuic acid, 



C 7 H a 4) 

 which is thus formed 



C 8 H 8 3 + 40 = C 7 H 6 4 + H 2 + CO 2 . 



"We have identified this substance by analysis, by the study of its 

 reactions, and also by transforming it into pyrocatechine, C 6 H 6 2 , 



The transformation into protocatechuic acid fixes the constitution of 

 vanilline. This compound is the methylated aldehyde of protocatechuic 

 acid ; its composition referred to benzol is represented by the formula 



/OCH 3 

 C.H^-OH 

 \COH. 



