1880.] 



Colouring-matters of Human Urine. 



213 



which was replaced by another one less shaded and nearer the red 

 when caustic soda was added. 



360 cub. centims. of the urine were precipitated with neutral and 

 basic acetate of lead and treated as before. The acidulated alcoholic 

 extract of the lead precipitate gave in deep layers no bands in red or 

 orange. This alcoholic extract was red in colour. In shallow layers 

 a black band was seen at F (Chart I, sp. 15 and sp. 16). 



The chlorof ormic solution was reddish-yellow and gave a black band 

 at F,* and a feeble shadow extending for about the breadth of the band 

 itself on its redward side. In deep layers no other bands could be 

 seen. The black band a. read from wave-length 501 to 482. The 

 pigment left after the evaporation of the chloroform was reddish- 

 brown in colour, and behaved like febrile urobilin as to solubility. 



Alcohol dissolved it, giving a reddish-yellow solution, which with 

 caustic soda became perhaps slightly redder, and it then gave in deep 

 layers sp. 17, Chart I, and in shallow sp. 18. These two bands at D 

 were seen when normal urobilin was treated with sodium amalgam, as 

 already referred to. (Vide supra.) 



With chloride of zinc another band appeared nearer the red in the 

 position of that produced by caustic soda. This pigment did not give 

 the same characters as normal urobilin, nor yet did it give exactly those 

 of febrile urobilin. From the appearance of the bands near D with 

 caustic soda, and taking into consideration the fact that these bands were 

 noticed when normal urobilin was reduced with sodium amalgam, I 

 believe the conclusion follows that this pigment was less oxidised than 

 normal urobilin and less reduced than febrile urobilin. 



I have selected this pigment to show that the statement made in my 

 former paper was correct, and that urobilin f appears capable of 

 existing in different states of oxidation. I have come to the conclu- 

 sion that the greater the number of feeble absorption-bands noticed, 

 the less the oxidation to which the pigment has been subjected in the 

 body. As a type of a pigment which has been produced by reduction 

 only, I may refer to urohaematin. 



Preliminary Experiments on the Oxidation of Bile Pigments. — In 

 attempting to trace back normal and febrile urobilin to their origin, 

 one naturally begins with bilirubin ; consequently my first experiments 

 were made on solutions of bilirubin, obtained by treating human bile 

 with alcohol to precipitate the mucus, and then, after filtration, 

 shaking with chloroform. I was not aware that I was dealing with 

 solutions which might also have contained urobilin ; in fact, I had 

 come to the opposite conclusion, since such solutions failed to give a 

 band at F. But when one considers that, even in spite of the absence 



* It was noted that the shading on the redward side of the band at F was only 

 seen in chloroformic solutions. 



f This remark applies to pathological pigments more especially. 



