CONDITIONS FATOURING FERMENTATION. 



29 



method employed. All that he says on this essential point is as 

 follows : — " In some of the experiments the procedure described by 

 Dr. Eoberts was accurately pursued, save in one particular. . . . 

 His potash-tubes, however, were exposed to a temperature of 

 280° Fahr., while mine were subjected to a temperature of 220° 

 only." These experiments of Professor Tyndall, therefore, like 

 tliose of Dr. Eoberts, will only tend to confirm my statement that 

 the addition of potash in excess leads to negative results. They 

 have no other bearing upon my experiments, and they conse- 

 quently afford no evidence whatever as to the efficacy of the two 

 precautions, the necessity for which they were destined to illus- 

 strate, and to whose discussion I shall presently return. 



One other experimenter has also questioned my results, though 

 I cannot say that he has repeated my experiments. This is none 

 other than the illustrious French chemist himself, M. Pasteur. 

 In reply to a brief note of mine on the subject of these experi- 

 ments, which was sent to the French Academy, and in which my 

 exact method of procedure was not described, M. Pasteur accepted 

 the fact as true, but denied the interpretation. He, however, 

 instead of adding to the sterilized urine a quantity of liquor 

 potasssB almost sufficient to neutralize it, added, as he says, solid 

 potash which had been heated to redness, or a solution of pot- 

 ash heated to 230° F. (110° C), and this in quantity sufficient to 

 render the urine " alkaline." The result was (as I should have ex- 

 pected), that the urine so treated remained barren. This barrenness 

 I attribute to the fact that the potash had been added in excess ; 

 M. Pasteur, on the other hand, attributed it to the higher tempera- 

 ture to which the potash had been heated, and proclaimed his modi- 

 fied experiment as a triumphant vindication of the truth of his 

 previous theory. And yet it was not even this. His previous po- 

 sition was, that in neutral or slightly allcaline organic liquids cer- 

 tain germs were not killed at a temperature of 100° C. which 

 were killed at 110° C. Here, however, was liquor potassse, a 

 very strongly alkaline fluid, so caustic as to he capahle of dissolving 

 'protoplasm even when cold; and M. Pasteur would have us believe 

 that germs can, when immersed in it, resist a temperature of 

 100° C. — because he thought they did so in the very much weaker 

 fluid. Much evidence would be needed to bring conviction to the 

 minds of physiologists on this point ; and as yet none has been 

 offered. 



At present, therefore, my experiments have not been repeated 



