102 PHYSIOLOGICAL CHEMISTRY. 



thus far with only partial success. The substances which have been 

 extracted from the urine by various methods, as representing, more or 

 less exactly, its natural coloring matter, are known by the names of 

 Urochrome, Urosine, Urosacine, Hemaphaeine, Urohematine, Uroxan- 

 thine, Urobiline, and Hydrobilirubine. Most of them are probably 

 modifications of the same substance, variously altered by the methods 

 of extraction, or obtained in different grades of purity. The fresh, 

 normal urine has a light yellowish or amber color, while specimens of 

 unusually high specific gravity, and particularly specimens of febrile 

 urine, often exhibit a distinct reddish hue. Normal urine, which, when 

 fresh, is only amber-colored, will often acquire, by exposure to the air, 

 a tinge of red. The substance obtained by Thudichum,* and called by 

 him urochrome, is precipitable from the urine by various metallic salts. 

 It has not yet been produced in a crystalline form. It is soluble in 

 water and in ether, but only slightly soluble in alcohol. Its watery 

 solution has a yellowish color, which, on standing, becomes red. 

 Urohematine (Harley) is nitrogenous in composition, and contains 

 iron.f It is insoluble in pure water, but soluble in the fresh urine, as 

 well as in ether, chloroform, and alcohol. The substance termed Uro- 

 biline (Jaffe) was so named to indicate its derivation from the coloring 

 matter of the bile. It is identical with hydrobilirubine (Maly), 

 which is produced from bilirubine by hydration and deoxidation by 

 means of sodium-amalgam. The change which takes place in this 

 process is as follows : 



Bilirubine. Urobiline. 



2(0^8^03) + 2(H 3 O) O = C 32 H4oN 4 O 7 . 



TJrobiline is soluble in alcohol, ether, and chloroform. Its solutions 

 have a brownish-yellow color, and, by dilution, become first yellow, 

 and lastly faint rosy -red. It was found by Jaffe J in many cases in 

 human urine, where it was recognized, after partial extraction and 

 purification, by its spectroscopic properties; showing an absorption 

 band at the junction of the green and the blue, between the lines E 

 and F. But the same observer found that fresh urine, not subjected to 

 chemical manipulation, would often present no indication of urobiline. 

 If secluded from the atmosphere, it would remain light-colored ; but if 

 exposed to the air from two to twelve hours, it would become darker 

 in hue, and at the same time would show, by the spectroscope, signs 

 of urobiline. This substance consequently is not now regarded as the 

 normal coloring matter of the urine, but as a product of its alteration. 



It is evident, however, that the urine contains a coloring matter, 

 derived in all probability from the bile, which gives to it its well-known 

 amber tint. This substance is liable to be changed under the influence 

 of oxidation, and to assume in that condition a more or less distinctly 



* British Medical Journal. London, Nov. 5, 1864. 



f Harley, The Urine and its Derangements. Philadelphia, 1872, p. 97. 



J Archiv fur pathologische Anatomie und Physiologic, 1869, Band xlvii., p. 405. 



