306 SUBSTANCES FOUND TO POSSESS 



C 8 H 4 O 10 + C 4 H 5 0, HO, is formed at an ordinary 

 temperature, if tartaric acid be brought into contact 

 with alcohol. 



This is the case in wine, and this acid combined 

 with oxide of ethyl will therefore be found in all 

 wines. It crystallises in rhombs, is destitute of smell, 

 and has a sweet sour taste ; if it be produced from 

 free acid in wine, the wine must become sweeter. 



Distillation with water converts it into alcohol and 

 tartaric acid. "We have, therefore, no means of de- 

 tecting its presence in wine, though we feel convinced 

 that it does exist. 



Eacemic ether and water, C 8 H 4 O 10 + C 4 H 5 O, 

 2 HO. This substance is distinguished from the pre- 

 ceding by containing one more equivalent of water. 

 In other respects it entirely corresponds to it ; it will 

 be found in wines containing racemic acid, although 

 its presence also cannot be proved. 



Citric ether, C 4 H 2 O 4 + C 4 H 5 O.-This is a 

 yellowish oily liquid, which, having itself the smell of 

 sweet oil, cannot certainly impart fragrance to the 

 wine. The presence of this ether compound in wine 

 cannot be proved, as distillation with water resolves it 

 into alcohol and citric acid. It would make Burgundy 

 wine bitter. (Compare p. 130.) 



Malic ether, C 4 H 2 O 4 + C 4 H 5 0, coincides in 

 most points with citric ether, and is equally decom- 

 posed by distillation. 



Fumaric ether, C 4 HO 3 + C 4 H 5 O. This ether 



