336 THE FERMENTATION OF UREA. 



of the bladder, a circumstance which would also account for the 

 alkaline reaction of this urine when in a freshly voided condition. 

 This statement was investigated and confirmed by PASTEUR and 

 JOUBBRT (II.) in 1876. On the other hand, the attempts made 

 by LEUBB (I.) to separate the enzyme from the bacteria by filtra- 

 tion through a clay cylinder failed. P. MIQUEL (VII.) then 

 showed, in 1890, that these conflicting results are due to the 

 extreme decomposibility of this enzyme, which he proposed to 

 name urase, and which, being very easily oxidised, ought to be 

 filtered in an atmosphere devoid of oxygen, a precaution neglected 

 by Leube. Urase decomposes in three to four hours at 50 C., 

 and in a very few minutes at 80 C. With regard to its chemical 

 composition nothing is at present known ; not even whether it is 

 a single body or a mixture of several substances (varying in con- 

 stitution according to the conditions of fermentation). One thing, 

 however, Miquel placed beyond doubt, viz., its capacity to hydro- 

 lyse and rapidly convert urea (in a sterilised solution) into am- 

 monium carbonate. It is therefore a true enzyme. 



190. The Decomposition of Uric Acid and 

 Hippurie Acid. 



With regard to the disruption of the uric acid molecule by 

 microbial agency, F. and L. SESTINI (I.) instituted an investigation, 

 according to which the decomposition corresponds to the equation : 



/NH C NH\ NH 4 V 



/ H ^C = O + 8H 2 + 30 = 4 .XJO 



= o c H X Jar 



= o c NH X 



NH-C = O 



Unfortunately, pure cultures were not employed in this research, 

 which was published in 1890, and the same defect attaches to an 

 investigation made by E. GERARD (I.) in 1896. 



In a chemical sense, the statement just recorded was confirmed 

 by the treatise of Burri and his co-workers, mentioned in 187. 

 These workers also included the decomposition of hippuric acid 

 in the scope of their labours. Like their Italian colleagues, how- 

 ever, they did not employ pure cultures of ferments, but used " a 

 drop of manure drainings " for inoculating the media. They found 

 that hippuric acid was not attacked per se, but only when in com- 

 bination with lime, the decomposition, moreover, being more 

 difficult to effect than was the case with uric acid or urea which 

 last named is the easiest of all to convert into ammonium carbonate. 

 Both for the sake of completeness and also to show the necessity 

 for a more accurate investigation of the decomposition of hippuric 

 acid, we must refer to a remark made by Van Tieghem in his 

 above-mentioned treatise, namely, that his B. urece is capable of 



