COLOURING MATTERS IN WINE. 225 



added it remains red, and this is not, therefore, the 

 cause of wine colour in wine. If a trace of gum or 

 albumen be added the colour remains bright red. 

 Hence some of the constituents of wine have no effect 

 upon its colour. The colour must, therefore, be pro- 

 duced by some body possessing basic properties, and 

 which can at least act instead of a base, since it is 

 able to neutralise the strong tartaric and acetic 

 acids of the wine. "We must not forget that grape 

 juice itself has an acid reaction, and contains free 

 acids, and that in wine, acetic acid is added to tartaric 

 acid. Sugar added to red solution of colouring matter 

 has no effect upon the colour. 



In short, I have never been able to obtain pure 

 wine colour by adding one or many of the compo- 

 nents of wine to a red solution of colouring matter ; 

 it was and remained red. The case is simpler here. 

 If the solution of colouring matter in alcohol with 

 tartaric acid be diluted with water, the genuine wine 

 colour is produced. The addition of this water 

 makes the colouring matter less soluble, and gives it a 

 colour differing from what it has when more com- 

 pletely dissolved in pure alcohol and tartaric acid. 



From 10 to 20 per cent, alcohol is contained in 

 wine ; I am speaking of red wines. The free acids or the 

 cream of tartar cannot retain the colouring matter in 

 complete solution, and even if the colouring matter 

 be chemically divided among the ingredients of wine, 

 as is the case with acetate of alumina, the fact that 



Q 



