TANIQC ACID IN WINE. 189 



Nevertheless, I am of opinion that a trace of gallic 

 acid may easily occur in wine. 



"We have seen that no tannic acid exists in the 

 grape juice. If it is found in liqueur, or colourless 

 wine, it proceeds either from the skins which were 

 allowed to ferment, or from such sparingly soluble 

 substances as passed into the juice during the pressing 

 and crushing of the grape-skins. It may also pro- 

 ceed partially from the fruit-stalls, or from the grape- 

 stones, if these have been allowed to ferment, since 

 they contain a good deal of tannic acid. 



The amount of tannic acid in Madeira, Ehine, Tene- 

 riffe, Muscadel, Champagne, and other wines which 

 are not red, may be wholly disregarded when con- 

 sidering them medically, or dietetically, for the quan- 

 tity is too insignificant to affect even their flavour ; 

 at least the wines we are now considering have not, 

 as is well known, a trace of astringency in their 

 flavour. It is, however, a question, whether such wines 

 as contain but little sugar do not owe their flavour, at 

 least partially, to tannic acid. 



I have not attempted to determine the tannic acid 

 contents of wine, because I was not acquainted with 

 any method of accomplishing it in such a manner as 

 to be largely and generally useful. 



I can safely assert that traces of tannic acid may be 

 found in all white wines. A scarcely perceptible trace 

 was detected by means of chloride of iron in Bor- 

 deaux Sauterne ; it was more perceptible in Cham- 



