A VINOUS SMELL. 319 



sufficiently clear that this is a peculiar monobasic 

 acid, according to the ordinary, not the double for- 

 mula, which nevertheless fully expresses the com- 

 pound, 2 (C 6 H 6 O 4 ) = C 4 H 4 O 4 + C 8 H 8 O 4 ; that 

 is, hydrated acetic and butyric acid. 



This acid is formed out of tartaric acid. Acetic 

 and butyric ether appear in cellared wine ; they may, 

 as we see, be formed in combination from the decom- 

 position of tartaric acid. If this be the case, then 

 tartaric acid is thereby decomposed, the wine becomes 

 less acid, and this is observed to occur as the wine ages. 

 (Compare p. 111.) 



Butyric and acetic ether are odoriferous components 

 of wine. If aceto-butyric acid forms a compound ether, 

 it also must be sought among the constituents of wine. 



It is known that tartaric and citric acid, without 

 lime, and dissolved in water in a pure state, contain, 

 after a time, a large amount of acetic acid. The 

 decomposition of tartaric acid in wine can no longer 

 be doubted. 



There is, therefore, a real connexion between the 

 gradual sweetening and increase of aroma in wine, 

 which occurs in the course of time. 



"When we now bring this to bear upon what we 

 have already said respecting the facility with which 

 etherised tartaric acid is formed, then we perceive 

 that butyric and acetic ether may be produced by 

 the change of the tartaric acid in wine into butyric 

 and acetic acid. 



