112 



Prof. H. E. Armstrong and Mr. E. Horton. [Jan 26, 



consequence in such a discussion, as it is probable that a solution of the 

 substance contains both rnetameric forms of the compound and that each of 

 these can pass over into the other as required. Such molecules would be 

 converted by the combined action of ammonia and water into a dihydroxy- 

 diamino-methane or diamino-methanediol : 



The dehydration of the diol might well occur in either of two ways and 

 give rise to one or other of the two forms of urea : 



Such dehydration changes would take place, we may suppose, the more 

 readily the more concentrated the solution and the higher the temperature ; 

 they would be promoted by the presence of salts, as these would " concen- 

 trate" the solution; and would also be promoted by non-electrolytes, as 

 these would raise the osmotic tension in the solution and render the water 

 itself more active as a dehydrating agent. 



Amnionic salts and cyanates, in common with all other salts, would act as 

 " dehydrating " agents and therefore as accelerators. The effect produced by 

 salts other than these, however, would be two-fold : whilst active as 

 accelerators, they would also tend to confer stability on the cyanate, in virtue 

 of the occurrence of changes such as the following : — 



Ammonia, being so very weak a base, would have a relatively slight 

 effect in promoting the formation of the diamino-derivative and increasing 

 the amount of change : on the other hand, by increasing to some extent the 

 activity of water, it would to some extent perhaps also counteract its own 

 tendency to increase the proportion of diamino-derivative produced, whilst it 

 would in some degree promote dehydration changes. It may be expected, 

 therefore, that the aggregate effect of ammonia would be slight. 



Hydrolysis of Urea, by Soja Urease. — It is well known that though urea 

 does not undergo hydrolysis under ordinary conditions, it rapidly disappears 

 from voided urine — the reason being that organisms which cause its destruc- 

 tion soon develop in the liquid. The hydrolysis is affected by urease, an 

 enzyme present in Micrococcus urae and a number of other organisms. The 



XH 3 4- OH 2 + CO-NH ^ C- 



OH 



^ C(N)OH + OH 2 + NH 3 . 



NH2 



XH4.CNO + KC1 ^ KCXO + NH4CI. 



