284 NON- VOLATILE CONSTITUENTS OE WINE. 



effect on the taste of the wine ; whilst the influence of 

 the colouring matter of red wine and of the apothema 

 of tannic acid is less decided ; on the other hand, the 

 tannic acid, especially in the red wines, has a decided 

 influence on the taste of the wine. However small the 

 quantity of gum may be, it serves when combined 

 with sugar to soften a little the sharp taste of the 

 acids ; the albumen is of no importance to the flavour. 



Lastly, only three substances are left ; first, the 

 extractive matter which is present in the grapes, a 

 substance which appears in many plants, is found in 

 all parts of the plant, and may be so prepared as to 

 serve for medical purposes as an extract, or may be 

 chemically determined by evaporating a watery extract. 

 Secondly, a soluble substance formed during the de- 

 composition of ferment. Thirdly, a substance which 

 remains over during the saccharine fermentation, 

 and invariably succeeds, however great the quan- 

 tity of ferment may be in withdrawing a portion of 

 sugar from its influence. We have already spoken of 

 all these substances, and have now only to consider 

 the wines with a view to that which is left after 

 evaporation, so as the better to compare them. 



The sweetest wines leave the largest residue after 

 evaporation; it amounts sometimes to one-fourth of 

 their weight. 



Besides these, ordinary Rhine and French wines 

 differ but little in the total amount of solid matter ; 

 they contain on an average 2 per cent. The better 

 wines, on the contrary, contain as a rule more, in 



