GOLOTJKING MATTEBS IN WINE. 217 



water is only slightly coloured yellow by a little 

 apothema of tannic acid, which still remains in it; 

 and in order to remove which, boiling with water is 

 necessary. 



After boiling, the colouring matter is found nearly 

 pure in the sulphide of lead. Tartaric acid, gum, 

 sugar, tannic acid, &c., and all inorganic salts, are all 

 withdrawn, but not the fat. 



Since colouring matter is insoluble in alcohol, it is 

 not separated by boiling sulphide of lead with alcohol. 

 It is completely insoluble in alcohol ; may how- 

 ever be dissolved in alcohol with acetic acid, and still 

 better in alcohol and tartaric acid, when it forms a 

 beautiful red tincture. If the sulphide of lead be 

 entirely freed from red colouring matter by alcohol 

 and tartaric acid, no apothema of tannic acid can be 

 removed from it by means of ammonia, since it has 

 already been dissolved out from the sulphide of lead 

 by the boiling water. 



I will first endeavour to prove that no apothema of 

 tannic acid exists with the red colouring matter in 

 the alcoholic tartaric acid extract. If the tartaric 

 acid in the red alcoholic tincture be carefully satu- 

 rated with ammonia, tartrate of ammonia will be 

 precipitated. 



The liquid when nearly saturated with ammonia, 

 and freed from tartrate of ammonia by the addition of 

 alcohol, has the colour of a pale solution of chrome 

 alum without a tinge of brown. It cannot be evapo- 



