1880.] 



Colouring-matters of Human Urine. 



227 



evaporated off, it leaves a brown-yellow amorphous pigment. It is 

 soluble in the same solvents as choletelin and normal urobilin. The 

 chloroformic solution appears yellow on a white dish, giving a reddish 

 tint where the fluid touches the white dish, and it gives a band, ft or 7, 

 from wave-length 510 to wave-length 484, with ill-defined edges. 



Alcohol* dissolved the pigment, forming a yellow solution giving a 

 band, 7, from wave-length 507 to 482. When this yellow fluid was 

 treated with caustic soda it became orange, and gave, in deep layers, 

 general absorption of the violet up to wave-length 534. In shallow 

 layers no band was visible. 



Zinc chloride caused the fluid to assume an orange colour, and then 

 the spectrum was shaded up to wave-length 538. In a thinner layer 

 a band became detached (though this was not easily seen) from about 

 wave-length 526 to 501 (?). 



When the fluid treated by zinc chloride was treated with caustic 

 soda, the orange- coloured fluid became yellow, and a feeble shadow 

 from wave-length 513 to 488 was just visible. 



Re-acid ified after treatment with caustic soda a black band came 

 back in the original position. The above characters are sufficient to 

 establish the identity of this pigment with normal urobilin and with 

 choletelin ; but its action with sodium amalgam completely proved 

 the truth of this supposition. 



Artificial Production of Febrile Urobilin from the Pigment produced by 

 Oxidation of Hcematoin. — When this brown-yellow pigment is dis- 

 solved in alcohol, it gives a yellow solution ; when it is diluted with 

 water and sodium amalgam introduced the colour soon becomes orange. 

 After longer action, especially when a gentle heat is applied, the fluid 

 again becomes paler, until at last it assumes that of pale sherry. 

 (See sp. 16, Chart III.) When sulphuric acid is added to acidity, 

 the fluid becomes orange-red, and then three bands are visible, one 

 before D, one between D and E, and a black one at F, sp. 17. But 

 if instead of using strong sulphuric acid, it is added in the pro- 

 portion of two parts acid to twelve alcohol, and the fluid is then 

 shaken with chloroform, the latter takes up the pigment forming 

 a red solution, which appears yellow in thin layers. On evaporating 

 the chloroform, a reddish-brown pigment is left. This dissolves in 

 alcohol with a red colour, and gives in deep layers no bands near D, 

 but in shallower ones a black band at F. It will, therefore, be seen 

 that strong sulphuric acid has the property of so changing the 

 chromogen of the reduced pigment, as to produce two bands near D, 

 as well as that at F. I believe that this may account for the presence 

 of certain feeble bands near D, seen in solutions of febrile urobilin. 

 (See "Proc. Roy. Soc," vol. 31, p. 26.) 



If to the alcoholic solution of the pigment of a red colour, and 

 * Ordinary rectified spirit. 







