486 



COLORING-MATTERS OF THE URINE. 



and if this be permitted to evaporate, it remains as a residue. It is soluble in 

 ammonia-water or in dilute soda-solution. If urobilin be dissolved in dilute 

 sodium hydrate and a small amount of calomel be added, the yellow solution 

 becomes rose-red (urorosein). If a chloroform-extract be prepared by agitation 

 of urine containing urobilin, and if iodin be added, and be combined by agitation 

 with dilute potassium-solution, the solution acquires a color varying from yellow 

 to brownish yellow, with a beautiful fluorescence in green. This reaction can also 

 be applied directly to any urine containing urobilin. At times the urobilin, on 

 standing, undergoes a modification, and then the usual reactions fail. 



If sodium or potassium carbonate be added to the urine, the characteristic ab- 

 sorption-band at F approaches b and becomes much darker and more sharply de- 

 fined. According to Hoppe-Seyler and Saillet, urobilin develops in the urine only 

 after evacuation by the taking up of oxygen on the part of another body forming 

 urobilin (Jaffe's chromogen). If acetic ether be added to recently discharged 

 urine acidulated with acetic acid and agitation be practised, the chromogen passes 

 over into the ether. If the acetic ether be agitated in sunlight with water, uro- 

 bilin is formed; and this can be again shaken out by means of chloroform. If 

 zinc chlorid be added to urine containing urobilin and rendered alkaline by addition 

 of ammonia, the urine exhibits marked fluorescence, with a distinct green luster, 

 particularly in reflected rays of sunlight. The isolated urobilin is fluorescent also 

 without addition of zinc chlorid. Phosphotungstic acid precipitates all urobilin 

 as a rose-colored deposit, which is soluble in water, and, after addition of hydro- 



Red. Orange. Yellow. 



_-~~ 



B 

 40 



Green. 



70 SO 9O 10O 110 



FIG. 151. Spectrum of Urobilin in Acid Urine. 



Red. Orange. Yellow. Green. Cyan-blue. 



' -^ 



110 



A a JB C 



40 50 



D 

 60 



El) F 



70 80 00 100 



FIG. 152. Spectrum of Urobilin in Alkaline Urine. 



chloric acid, also in chloroform. By the employment of reducing agents (sodium- 

 amalgam) a colorless reduction-product is formed from urobilin; but this, on 

 standing in the air, is retransformed into urobilin, with the taking up of oxygen. 

 The colorless body is identical with the chromogen that Jaffe found in urine. 

 In many cases of jaundice, in which, at times, Gmelin's test for biliary pigment 

 fails to develop, urobilin is present, particularly when incomplete biliary stasis 

 exists. This urobilin-icterus occurs especially after the absorption of considerable 

 extravasations of blood. According to Cazeneuve, the urobilin is increased in all 

 diseases that are attended with increased destruction of red blood-corpuscles. 



Urochrome is considered by Thudichum as the peculiar yellow coloring-matter 

 of the urine. It can be isolated in yellow crusts that are soluble in water, as 

 well as in dilute acids and alkalies. The watery solution oxidizes in the air, with 

 the development of a red color through the formation of uroerythrin. Treated 

 with acids, further decomposition-products appear; among them, uromelanin. 

 The uroerythrin often gives the urates a red color, the urochrome a yellow color. 

 The latter, however, is by many not considered a well-characterized chemical 

 body. Human urine saturated with ammonium sulphate yields, on agitation with 

 90 per cent, phenol, all of its coloring-matter to the latter. If this solution of 

 phenol be mixed with ether and water, the water is stained yellow (urochrome), 

 the phenol-ether mixture red (urobilin and hematoporphyrin) . 



