624 



THE CHEMISTRY OF THE URINE. 



its solutions are decolorised by light ; and (3) its colour reactions 

 with the caustic alkalies and mineral acids. The pigment invariably 

 associates itself with urates during their precipitation ; either when they 

 separate naturally from a urine containing it, or when they are arti- 

 ficially added to its pure solutions, and are allowed afterwards to separate. 



7. I 



2. 



B. C. 



D. 



E. b. F. 



FIG. 57. Chart of spectra. 



1. Acid hsematoporphyrin. 



2. Alkaline hsematoporphyrin. 



3. Hsematoporphyrin as found in urate sediments. 



4. Acid urohilin concentrated. 



5. Acid urobilin dilute. 



6. The E band spectrum. 



7. Uroerythrin. 



8. Urorosein concentrated on dilution the band 



shrank rapidly from redward end. 



It apparently forms a loose compound with the urates, as a special 

 absorption-spectrum is seen when light passes through the pink pre- 

 cipitate, differing from that proper to solutions of the pigment (Garrod). 

 The best solvent of uroerythrin is amylic alcohol ; acetic ether is but 

 little inferior, and the pigment is also soluble in alcohol, chloroform, and 



