122 PASTEUR: THE HISTORY OP A MIND 



tension, the different processes of vinegar-making by 

 oxidation of the alcohol in wine or fermented liquors. 



Owing to his study of the different processes employed 

 in his vicinity, since the time of Schutzembach, by the 

 vinegar manufacturers of Germany, he had some right 

 to make this comparison. In a pile of casks with the 

 heads knocked in, and forming a hollow column several 

 meters in height, are piled loosely shavings of beech, 

 over which is showered a feebly alcoholic liquid to which 

 have been added some milligrams of acetic acid and which 

 contains, furthermore, a little acid beer, sharp wine, or 

 some other organic matter in process of alteration, neces- 

 sary, according to the theory of Liebig, to act as a fer- 

 ment and set in motion the phenomenon. Under these 

 conditions the shavings play the role of the platinum 

 black and do it more economically. On coming into 

 contact with them the alcohol oxidizes, the mass be- 

 comes heated, and the pile of casks forms a chimney for 

 a current of air, which, entering below, diffuses through- 

 out the mass, bringing constantly to all points new oxy- 

 gen, so that the process of acetification progresses 

 rapidly. As with platinum black, there are sometimes 

 formed, in addition to the acetic acid, suffocating prod- 

 ucts with the odor of aldehyde. Finally, to complete 

 the resemblance, the shavings seem to act only by their 

 presence. After 10 or 20 years of use in the manufacture 

 of vinegar, they are intact, being as sound and clean as 

 on the first day. 



We will acknowledge that the comparison was tempt- 

 ing, and will understand that Liebig could not resist the 

 temptation. One falls easily on the side toward which 

 he leans. Pasteur was entitled to look upon the question 

 quite differently. In connection with his studies on 

 spontaneous generation, he had just determined that all 

 organic substances oxidize very slowly in contact with 



