118 CELLARING. 



pieces of oak. The Bosnian oak (from the shores of 

 the Adriatic) affects white wine so strongly, by im- 

 parting to it a large portion of tannic acid, that ex- 

 posure to the air will often turn such wine black. 

 This wood is, therefore, not suited to wine-casks. 

 French oak (from Angoumois) is less injurious, 

 although it gives a good deal of tannic acid to the 

 wine. 



The case is different with red wines, which already 

 contain a certain proportion of tannic acid, and 

 whose quality cannot be much affected by a slight 

 increase in this' ingredient. The colouring matter of 

 the wood is fixed by the colouring matter of the wine, 

 but such of the constituents of the wood as impart 

 flavour and odour may pass into the wine. Faure 

 does not approve of previously treating the wooden 

 casks with alkalis, since alkalis render tannic acid 

 darker; instead of this he recommends sulphuric acid 

 with water (A sulphuric acid), to be left standing 24 

 hours, and the casks afterwards washed out with 

 water. In considering the action of oak upon wine, 

 we must distinguish between coloured and non- 

 coloured wines. All light-coloured wines suffer greater 

 or less alteration, and we shall speak more particu- 

 larly about them in considering the colouring matter 

 of wine. 



"We must also make a distinction between old and 

 new casks. Old casks, which have already been used 

 for the same purpose, have either entirely, or in great 



