THE PIGMENTS OF THE UKINE 



215 



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 easily to acetic ether or to amylic alcohol. 



FIG. 03. Chart of absorption spectra : 1, acid heematoporphyriu ; 2, alkaline haeuiatoporphyrin : 

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

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

 centratedon dilution the band shrinks rapidly from redward end. (After F. G. Hopkins.) 



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

 those of alkaline haematoporphyrin (fig. 63, spectrum 2). On adding sulphuric 

 acid the spectrum of acid hsematoporphyrin is seen (fig. 63, spectrum 1). 

 Occasionally urate sediments are pigmented with a form of the pigment which 

 shows a two-banded spectrum, very like that of oxyhaernoglobin (fig. Co, 



