488 M. H. Bleibtreu on Cumarine. 



acid. There however in this latter case always remains, even 

 after long treatment, a large portion of cumarine undecom- 

 posed. 



The evolution of hydrogen mentioned by Delalande, and 

 which, as already stated, I never observed in a well-conducted 

 experiment, arose evidently from the formation of salicylic 

 acid by the further action of the potassa on the cumaric acid. 

 This view is supported by the violet-coloured reaction of ses- 

 quichloride of iron described by him, and which, as I have 

 shown, does not belong to cumaric acid. His cumaric acid 

 evidently contained a small quantity of salicylic acid. 



From the aforesaid grounds, the view taken by Delalande 

 on the transformation of cumaric into salicylic acid must also 

 be modified. According to him, no evolution of hydrogen 

 takes place in this formation, but an aromatic gas is disen- 

 gaged burning with a coloured flame, and which he regarded 

 as a carbo-hydrogen C 4 H 2 , representing the difference of 

 constitution between the two acids — 



HO,C, 8 H 7 Q, - C 4 H 2 = HO, C 14 H 5 6 . 



Hydrated cumaric acid. Aromatic gas. Hydrated salicylic acid. 



This manner of viewing the reaction is evidently incorrect. 

 If pure cumarine is fused with hydrate of potassa, the latter 

 is almost entirely transformed into carbonate after the forma- 

 tion of the salicylic acid. The carbon therefore separates in 

 the form of an oxygenated compound. 



I have made no quantitative experiment on this point ; but 

 all my observations tend to prove that the formation of the 

 salicylic acid may be represented by the following equations : — 



HO,C 18 H 7 O 5 + 8HO = HO,C 14 H 5 O 5 + 4CO 2 + 10H. 



v I . v y / 



Cumaric acid. Salicylic acid. 



As to the aromatic gas burning with a brilliant flame, which 

 is evolved in the latter stages, it is no carbo-hydrogen, but 

 the oxide of a carbo-hydrogen, viz. hydrate of phenyle, arising 

 from the further loss of carbonic acid from the salicylic acid 

 already formed, — 



HO, C 14 H 6 O s - 2C0 2 = HO, C 12 H s O. 



V ., , » < y -J 



Salicylic acid. Hydrate of phenyle. 



Nitrocumarine. 



Delalande has studied the action of nitric acid on cuma- 

 rine. The correction of the formula of the latter body made 

 it desirable to repeat this experiment also, as it was probable 



