COLOURING MATTEES IN WINE. 235 



had not the sediment contained a little free acid ; 

 probably he had a mixture of all such substances as, 

 being in the sediment, are soluble in alcohol and 

 water, except tannic acid, which he precipitated with 

 gelatine. 



According to Batilliat, nearly the whole of the 

 sediment of old wine is composed of purpurit. After 

 combustion, lime, iron, and potash are found in it. 

 This purpurit exhibits itself so evidently as a mixture 

 of blue colouring matter and apothema of tannic acid, 

 that no further proofs are needed. 



"What, therefore, Batilliat has adduced respecting 

 the colouring matter of wine is likewise inaccurate. 



It would be by no means a useless undertaking to 

 compare the colouring matter of wine with that of 

 other plants or fruits. This is almost necessary to a 

 thorough acquaintance with wine, especially if adul- 

 terations are to be detected. I should not have hesi- 

 tated to make the attempt myself, had it been pos- 

 sible to obtain fruits for this purpose at that season of 

 the year in which these analyses were made, but I 

 must now defer it to another time. I consider it not 

 improbable that the same blue colouring matter may 

 be met with in other fruits. 



Many colouring matters have the property of un- 

 dergoing rapid transformation when exposed to the 

 action of air. Berzelius* notices the alteration under- 

 gone by the colouring matter of cherries and black- 



* Lehrbuch, Bd. 7, s. 159. 



