CONDITIONS FAVOURINa FERMENTATfON, 



87 



This latter statement would not give one mucli reason to believe 

 that the conversion of urea into carbonate of ammonia took place 

 very readily in urine under the mere influence of warmth. And 

 this impression was strengthened in my mind by the fact that no 

 allusion was made to such a decomposition by M. Pasteur. I was, 

 indeed, impressed by opposite statements made by him. Eeferring 

 to a little chaplet-like organism common in unboiled fermenting 

 urine he said *: — " Je suis tres-porte a croire que cette production 

 constitue un ferment organise, et qu'il n'y a jamais transformation 

 de I'uree en carbonate d'ammoniaque, sans la presence et le de- 

 veloppement de ce petit vegetal. Cependantmes experiences sur 

 ce point n'etant pas encore achevees, je dois mettre quelque 

 reserve dans mon opinion." On the same page M. Pasteur says 

 that if urine is boiled for two or three minutes in a vessel to which 

 only calcined air is admitted before it is hermetically sealed, and 

 if it is thereafter exposed in a stove to the influence of a tempera- 

 ture of 25° to 30° C. (77°-86° Fahr.), " il pent y sejourner in- 

 defiuiment, sans eprouver d'autre alteration qu'une oxydation 

 lente de la matiere albumineuse de 1' urine * * * la limpidite de 

 r urine reste parfaite, meme apres dix-huit mois, et il n'y appa- 

 rait pas la plus petite production animale ou vegetale ; elle con- 

 serve egalement son acidite et son odeur premiere." 



Under the influence of these statements I was at first not ap- 

 prehensive that the urea of the urine became sensibly converted 

 into carbonate of ammonia during a short ebullition, or that any 

 change of the same kind went on afterwards whilst it was in the 

 incubator. My attention, however, was specially directed to this 

 subject by a statement made by M. Pasteur in the early part of 

 the present year. He saidf : — " It is not useless to say here that, 

 contrary to what is generally admitted, urea in aqueous solution 

 or in urine is decomposed at 100° 0.> and even at temperatures 

 much lower. The product of decomposition is carbonate of am- 

 monia." This induced me to give special attention to this sub- 

 ject ; and the result has been the full confirmation of Pasteur's 

 recent statement, in opposition to his earlier impressions and 

 statements. 



If a piece of moistened red litmus paper is exposed to the steam 

 coming through the capillary orifice of a retort in which ordinary 

 acid urine is being boiled, this paper is for a time rendered faintly 



♦ Lot: cit. p. 52. 



t Compt. Rend. Jan. 8, 1877, torn. Ixxxiv. p. 64. 



