226 COLOUEING MATTEES IN WINE. 



colouring matter is but sparingly soluble in alcohol 

 and water sufficiently explains the peculiar colour it 

 has in wine. 



For the same reasons strong acids, as sulphuric 

 and nitric acids, by dissolving the colouring matter, 

 more completely make it redder thau tartaric acid. 



I must here insert the following remarks. It is 

 known that carbonic, boracic and other weak acids, 

 impart to so-called blue vegetable colouring matters 

 a wine colour, e. g. litmus tincture, not a bright 

 red, as do muriatic and sulphuric acids. These weak 

 acids stand in the same relation to the ammonia of 

 the litmus colouring matter as do acetic acid and 

 alumina to that of wine, that is, they take part in the 

 combination, but neither is able completely to over- 

 power the other. 



Muriatic acid overpowers ammonia -in litmus. Bo- 

 racic acid does not. "What remains of the blue 

 colouring matter is insignificant in quantity, but may 

 be easily distinguished; the effect of the ammonia 

 is almost, though not entirely, removed. 



The details respecting the colouring matter com- 

 mon to all red wine, which have thus been narrated, 

 give us a large view of the endless variety in colour 

 of which red wine is capable. The colour is not 

 determined entirely by the quantity of colouring 

 matter present, for it partly depends on the quantity 

 of free acids, and is also affected by the quantity of 

 substances which compete with acids, and are, like 



