' 



1894.J of the Yellow Colouring Matter of the Urine. 397 



soluble in ether, with a port wine colour, and showing an absorption 

 band to the more refrangible side of D (omicholic acid), a portion 

 soluble in alcohol, showing a band extending from E to beyond P 

 (uropittine), and a residue scarcely soluble in water or alcohol, but 

 ily dissolved by alkalies (uromelanine). 



hudichum assigns to urochrome a faint absorption band at F, and 

 was led to regard the pigment as a feeble alkaloid, on account of its 

 icipitation by phosphomolybdic acid. 



chunck* (1867) employed the acetates of lead as precipitants, and 

 racted the colouring matter with cold sulphuric acid or sulphuretted 

 hydrogen. He came to the conclusion that the urine owes its colour 

 to two distinct yellow pigments, one soluble and the other insoluble 

 ether. 



he pigment' soluble in ether (urian) yielded, on heating with 

 mineral acids, a brown resinous substance, readily soluble in alcohol 

 (uroretine), whereas the pigment insoluble in ether (urianin) yielded 

 a brown flocculent substance scarcely soluble in alcohol (uro- 

 melanine). He made numerous combustion analyses of these pro- 

 ducts, and his results differed widely from those of Tichborne, espe- 

 cially in the much smaller percentage of carbon found. For urian, 

 the pigment soluble in ether, Schunck obtained the percentage com- 

 position C, 51-23; H, 5-38; N", 1'26 ; 0, 42'13. Whereas urianin 

 gave 0,46-44; H, 5'66 ; 1ST, 3'16; 0,4474. 



In more recent years, Thudichum has on various occasions upheld 

 the claims of urochrome to be regarded as a definite chemical entity ,f 

 in reply to the criticisms of MalyJ and others. 



Dr. Lewis Jones, who, some years ago, made some investigations 

 on this subje'ct, has favoured me with an account of his results, which 

 were never published. He arrived at the conviction that the yellow 

 colour of urine could not be due to urobilin, which, in solution, has a 

 redder colour than urine. Moreover, the yellow pigment is insoluble 

 in chloroform, in which urobilin dissolves freely. Urobilin, even in 

 very dilute solution, has a very distinct absorption band at F, whereas 

 normal urine shows no band at F unless viewed in deep layers, and 

 then shows only a diffused obscuration about the region of the F line, 

 quite unlike the sharp band of urobilin. 



He found that an extract obtained by the lead acetate method, 

 evaporated in vacuo, with proper precautions, yielded a yellowish 

 crust, from which chloroform dissolved out any traces of urobilin. 

 The remainder, when dissolved in water, reproduced the colour of the 

 original urine when diluted to the same bulk. From normal urine 

 the amount of urobilin obtained was very minute ; more could be 



* Loc. tit. 



t ' Journal Chem. Soc.,' vol. 13, 1875, p. 892. 



% ' Ann. der Chem. und Pkarm.,' vol. 163, p. 90. 



