140 PASTEUR: THE HISTORY OF A MIND 



the moment of drawing off; it preserves its color; its 

 savor does not change to any appreciable degree ; it takes 

 on no particular bouquet ; it is always new wine. During 

 this time, the rest of the same wine, preserved in a cask 

 and subject to the ordinary manipulations, becomes old 

 in the complex sense which one ordinarily gives to this 

 word. What differences are there then between the two 

 wines? One only: under its envelope of glass the former 

 has not been subject to the action of the oxygen of the 

 air which filters constantly and slowly through the 

 barrel staves, and which, combining with the wine, 

 determines its ripening. 



Without taking any particular precautions to avoid 

 excess of air, let us repeat the experiment which I have 

 just described, leaving the bottle half empty and closed 

 with its stopper. While the wine in the previous ex- 

 periment remained young, that in the new bottle clouds 

 and gives an amorphous deposit which increases little 

 by little and finally adheres to the walls. It is the red 

 coloring matter which has separated from the wine. 

 At the same time, the oxygen left in the bottle dis- 

 appears, and the wine changes, loses its original savor, 

 becomes old, and takes on in a high degree the taste of 

 rancio, 1 if it is red, of madeira if it is white. It may 

 even fade away and disappear altogether, if there is 

 too little of it in proportion to the oxygen. 



The essential act in the aging of wine is, therefore, its 

 slow combination with oxygen. When the absorption 

 of oxygen is too rapid, the wine becomes vapid, but this 

 is a passing phenomenon, and it is often sufficient to 

 let the wine alone for this taste to disappear, as soon 

 as the oxygen absorbed in a gaseous state has served 

 in the wine for the oxidations which have consumed it. 



1 Old wine which has acquired the taste of Spanish wines. Trs. 



