THE PIGMENTS OF THE URINE 



179 



urine. In some pathological conditions, especially after the administration 

 of certain drugs (e.g. sulphonal), its amount is increased. Its amount is 

 stated to increase when the urine stands ; this points to the existence of a 

 colourless chromogen. It may be separated from the urine as follows : — 

 Caustic alkali is added to the urine; this causes a precipitate of phos- 

 B o D E 6 P G 



I 



BCD E ft F G 



Fig. 63. — Chart of absorption spectra : 1, acid hfematoporphyriu ; 2, alkaline bsematoporphyrin ; 

 3, hsematoporphyriu as found sometimes in urate sediments ; 4, acid urobilin, concentrated ; 

 5, acid urobilin, dilute ; 6, the E band spectrum of urobilin ; 7, uroerythrin ; 8, urorosein con- 

 centrated—on dilution the band shrinks rapidly from redward end. (After F. G. Hopkins.) 



phates, which carries down the pigment with it : the pigment may be dis- 

 solved out with chloroform. The chloroform is evaporated, the residue 

 washed with alcohol, and finally dissolved in acidified alcohol. Urines rich 

 in the pigment yield it easUy to acetic ether or to amylic alcohol. 



"When the urine is sufficiently rich in the pigment, the bands shown are 



m2 



