FEEMENTATIGN. 93 



from two to three days, in that of Medoc 6 days, 

 8 days in those prepared in the south of Prance, 

 which are especially meant for the table (vin ordi- 

 naire), 14 days is the longest time, and in this case 

 the wine has a very dark colour. The greatest care 

 must be taken to prevent the wine from becoming 

 acid, for during fermentation by the escape of car- 

 bonic acid, a superficial covering (chapeau) upon the 

 wine speedily forms, by which means the alcohol is 

 exposed to the influence of the air under circum- 

 stances resembling those which facilitate the rapid 

 formation of vinegar. To prevent the formation of 

 this superficial covering (cliapeau), the skins must 

 be constantly stirred. 



