1880.] 



Colouring-matters of Human Urine. 



207 



from a case where there may be but a slight departure from the 

 normal condition, the band at F is replaced by a band nearer the red, 

 when these reagents, caustic soda or caustic potash, are added ; but 

 ammonia causes its disappearance. The reason of this is, that in the 

 latter case, febrile urobilin is present. 



When, therefore, the pigment which gives the band at F is isolated 

 from healthy human urine, it should present the same spectroscopic 

 characters as the urine containing it. Such is the case : for when 

 normal chrome-yellow coloured urine is precipitated with neutral and 

 basic acetate of lead, the precipitate extracted with alcohol acidulated 

 with sulphuric acid, the acidulated alcohol containing the pigment 

 separated by filtration from the lead precipitate, the fluid diluted with 

 water and shaken with chloroform in a separating funnel, the chloro- 

 form separated, and then distilled off, a residue is left, which is a 

 brown-yelloiv, amorphous, nitrogenous pigment, soluble in alcohol, 

 •ether, chloroform, and benzol, also in acids, and which gives in its 

 various solutions the same band that was seen in the urine, and 

 altered in the same manner by reagents, as it was altered in that fluid. 

 While febrile urobilin gives a sharp black band at F of intensity «, 

 the band of normal urobilin is less marked at its edges, and is less 

 shaded than the former. Its alcoholic solution shows the band well, 

 and when this is treated with caustic soda, caustic potash, or ammonia, 

 it disappears. Sometimes its disappearance may not be complete, and 

 in that case, the pigment which I named urolutein in my former 

 paper may be present. The pigment may sometimes appear more 

 brown than brown-yellow in colour, and in that case it shows a 

 tendency to imitate febrile urobilin in its behaviour with the caustic 

 alkalies, for on their addition a feeble band may be noticed nearer 

 the red than the original band. More especially is this likely to occur 

 if the acidulated alcohol contains too much acid, or if the fluid be left 

 too long in the separating funnel.* As a general rule, the more the 

 colour of the pigment approaches to brown, or brownish- red in colour, 

 the more does it resemble febrile urobilin in its characters. The 

 colour depends upon the amount of oxidation to which it has been 

 subjected in the body, as well as on its artificial preparation, as I shall 

 endeavour to show afterwards. 



The band of normal urobilin is shown in Chart I, sp. 2. As a 

 general rule, it extends, when examined in a suitable depth of alcohol, 

 from wave-length 507 to wave-length 482. While alcoholic solutions 

 of febrile urobilin are red in colour, and become yellow with caustic 

 alkalies, the alcoholic solution of this pigment becomes redder with 

 caustic soda. This is well marked when the alcoholic solution is 

 treated with sodium amalgam, for after the introduction of this sub- 



* Because in that case the chromogen of febrile urobilin is oxidised into febrile 

 urobilin. (Vide infra.) 



. Q2 



