122 PASTEUR: THE HISTORY OF 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 products with 

 the odor of aldehyde. Finally, to complete the resem- 

 blance, 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 ques- 

 tion quite differently. In connection with his studies on 

 spontaneous generation, he had just determined that all 

 organic substances oxidize very slowly in contact with 



