1880.] Colouring-matters of Human Urine. 209 



stance, the colour of the fluid becomes orange-red, and general 

 absorption of the violet end of the spectrum takes place. This re- 

 action at once shows a likeness between this pigment and choletelin, 

 but even a more striking likeness is exhibited by the action of chloride 

 of zinc, for when the pigment in its alcoholic solution is treated with 

 chloride of zinc, the colour of the fluid at once gets redder, and it then 

 shows a narrow and sharp band nearer the red end of the spectrum. 

 The edge of this band nearer the red is the more abruptly shaded, 

 that next the violet shows a gradually decreasing shading. Thus, 

 taking an actual experiment : — 



Band before zinc chloride, wave-length 504 to wave-length 484. 



Band after zinc chloride (sp. 3). 



Dark part of band, wave-length 516 to wave-length 501. 

 Feeble shadow up to wave-length 484. 



If, now, caustic soda be added to the fluid treated by zinc chloride, 

 the precipitate being dissolved in an excess of that reagent, the fluid 

 becomes yellow, and the same band as that got by treating febrile 

 urobilin is then seen, of intensity c. Now Heynsius and Campbell* 

 found that choletelin acted in the same manner, for it could not be 

 made to give this band B, until it had been first treated with zinc 

 chloride. 



The following differences collected together were found to exist 

 between normal and febrile urobilin : — 



(1.) The acidulated alcoholic extract of the lead precipitate is 

 lighter in colour than that of febrile urobilin. 



(2.) The chloroformic solution is of a yellow colour, and when 

 poured on a Berlin dish it is seen to be slightly reddish where its 

 edge touches the dish. The same solution of the febrile urobilin 

 is red. 



(3.) The absorption-band in the urine, in alcoholic solutions and in 

 chloroformic solutions, has less well-defined edges and is less shaded 

 than that of febrile urobilin. 



(4.) The band at F is made to disappear by means of caustic 

 alkalies, while it is replaced by another in the case of febrile urobilin. 



(5.) The pigment is yellow-brown, febrile urobilin being reddish- 

 brown. 



When sodium amalgam is put into an alcoholic solution, as previously 

 mentioned, the colour becomes orange, but by continuing the action 

 longer, then acidulating with hydrochloric acid and shaking with 

 chloroform, and evaporating off: the chloroform, I obtained a brownish 

 pigment, which, when dissolved in alcohol and treated with caustic 

 soda, gave a band on each side of D (Chart I, sp. 4). Now, it is a 

 remarkable fact, that I subsequently observed the same bands on 

 * " Centralblatt f. d. Med. Wiss.," 1872, p. 696. 



