232 COLOUEING MATTERS IN WINE. 



amount of free acetic acid varies so much in Bur- 

 gundy, that though its darker colour cannot be 

 entirely ascribed to the small amount of acetic 

 acid, it must still be regarded as one of the principal 

 causes. 



It is well known that Burgundy is not affected in 

 the same manner by time as other dark-coloured 

 wines, Port, for example. 



The insignificant amount of tannic acid contained 

 in this wine is the reason ; on account of this the 

 wine spoils easily, and but little apothema (by which 

 the colouring matter of wine is precipitated out of 

 the solution) is formed by time in it. 



This fact, and the less amount of oxygen contained 

 in it, account for Burgundy wines being darker, and 

 remaining so, if they can be preserved for a length of 

 time. 



I think the colouring matters of wine have been now 

 sufficiently discussed, and it only remains for me to 

 consider the best analyses, and compare them with the 

 above, 



We pass over liqueur-wines at once, since there are 

 no analyses of them worth noticing. 



Eaure's Analyses, given in his " Analyse chimique 

 et comparee desYins du Departement de la Gironde," 

 1844, must first be mentioned. He speaks of two 

 colouring matters in red wine ; one blue, which dis- 

 solves easily in water, sparingly in alcohol, and is 

 insoluble in ether ; and one yellow, which is soluble 



