500 



Mr. G. S. Johnson. 



contains much chlorine, but no phosphoric acid, and yields a gummy 

 mass on evaporation. It exerts no reducing action either upon cupric 

 oxide or potassium picrate in boiliog alkaline solutions. 



Satisfied, therefore, that the granular precipitate which gradually 

 separated out from the filtrate from the above amorphous substance 

 contains the whole of the normal reducing agent of urine, I confined 

 myself to the examination of that compound. 



Physical Properties of the Mercury Salt of the Reducing Base of 



Urine. 



I have described this precipitate as granular, and it certainly 

 appears upon superficial observation to be a crystalline substance, as 

 indeed might be expected from its gradual formation, but microscopic 

 examination reveals some curious facts in connexion with it. 



Examined under a quarter-inch object glass, the substance is at 

 once seen to be perfectly homogeneous, and often has the appear- 

 ance of minute crystals united together in stellate groups; but 

 under a one-sixteenth inch object glass these stellate groups are 

 seen to be composed of a number of very minute and perfectly 

 spherical masses. I have watched the growth of these spherules 

 from a minute point to a little globe resembling an oil- globule. The 



Fig. 1. 



Microphotograph of Spherical Mercury Salt of Kreatinin, precipitated 

 from fresh normal human urine. x 1500 diameters. 



