246 FBEE ACIDS IK WINE. 



The quantity of acids in wine, that is, of acids with 

 which alkali may be saturated, and which are percep- 

 tible to the taste, and to which the equivalent of tartaric 

 acid, which is not combined with potash in wine, be- 

 longs, however insignificant it may be, is yet very 

 variable. "We have already made some mention of 

 the amount of free acids (p. 176), in speaking of the 

 different estimates of the alcoholic contents given by 

 different analyses. Most of them, however, give no 

 fixed quantity of acids, and do not even distinguish 

 acetic from non-volatile acids. According to Liiders- 

 dorff (p. 177), but very little difference exists between 

 the French and Ehenish wines with respect to the 

 total acid contents, while Fusenius (p. 178) considers 

 that the best Ehine wines generally agree with one 

 another, and contain about ^ per cent. 



Dietz found in Ehine wines (p. 178) from 0'33 to 

 0*78 grammes potash necessary to saturate all the free 

 acids : whilst Schubert found the maximum of free 

 acid to be 0*45 and 1*35, and the average O8 and 0'9. 

 Kersting (p. 183) found in the wines of the Berg- 

 strasse from 0'6 to 0'8 free acids. It is particularly 

 necessary to keep a distinction between acetic and 

 tartaric acid, as the flavour of the wine very much de- 

 pends on the preponderance of the one or the other. 

 From the analyses that have been already made we 

 learn that a considerable quantity of acetic acid is 

 contained in all wines, and that their harsh flavour is 

 by no means entirely to be ascribed to tartaric acid. 



