DISEASES OF WINE. 125 



disease increases, the colour becomes brown, the wine 

 turbid, and of a disagreeable taste, and may at length 

 disseminate foetid gases and leave an acid liquid. 



This disease is caused by a decomposition of tartar. 

 That such decomposition takes place is known, but we 

 are ignorant as to how it originates. Carbonate of 

 potash is formed out of cream of tartar, and so the 

 colouring matter of the wine is altered and turned 

 brown. In this manner the disease commences ; it is 

 then transmitted to the other constituents of wine, 

 and eventually turns the alcohol into acetic acid. 



Wine affected by this disease does not at first contain 

 more acid than it did previously, since this disease 

 differs from that which turns wine sour. The quan- 

 tity of alcohol remains the same. The colour of the 

 wine is first affected, and the taste becomes at the 

 same time insipid and disagreeable. Batillat* unjustly 

 ascribes this disease to the decomposition of purpit, 

 one of the colouring matters which he discovered in 

 wine, and which consists partly of the colouring mat- 

 ter of wine, and partly of an apothema of tannic acid. 

 Batillat's mistake consists in considering effect for 

 cause. 



In wine which is diseased in this manner, gelatine 

 can no longer precipitate purpit, or apothema of tannic 

 acid, since the acid tartar has been converted into 

 alkaline carbonate of potash, which transforms both 

 tannic acid and apothema of taunic acid into sub- 



* Traite sur les Tins de la France, p. 131. 





