UROBILIN. 707 



and others. The quantity is increased in hemorrhage and in diseases 

 where the blood-corpuscles are destroyed, as is the case after the action of 

 certain blood-poisons, such as antifebrin and antipyrine. It is also 

 increased in fevers, cardiac diseases, lead colic, atrophic cirrhosis of the 

 liver, and is especially abundant in so-called urobilin icterus. 



The properties of urobilin may vary, depending upon the method 

 of preparation and the character of the urine used; therefore only the 

 most important properties will be given. Urobilin is amorphous, brown, 

 reddish brown, red, or reddish yellow, depending upon the method of 

 preparation. It dissolves readily in alcohol, amyl alcohol, and chloroform, 

 but less readily in ether or acetic ether. It is less soluble in water, but 

 the solubility is augmented by the presence of neutral salts. It may be 

 completely precipitated from the urine by saturating with ammonium sul- 

 phate, especially after the addition of sulphuric acid (Mmu 1 ). It is 

 soluble in alkalies, and is precipitated from the alkaline solution by the 

 addition of acid. It is partly dissolved by chloroform from an acid 

 (watery-alcoholic) solution; alkali solutions remove the urobilin from 

 the chloroform. The neutral or faintly alkaline solutions are precipitated 

 by certain metallic salts (zinc and lead) , but not by others, such as mercuric 

 sulphate. Urobilin is precipitated from the urine by phosphotungstic 

 acid. It does not give GMELIN'S test for bile-pigments. It gives, on 

 the contrary, a reaction which may be mistaken for the biuret test, by 

 the action of copper sulphate and alkali. 2 



Xeutral alcoholic urobilin solutions are in strong concentration brownish 

 yellow, in great dilution yellow or rose-colored. They have a strong green 

 fluorescence. The acid alcoholic solutions are brown, reddish yellow, 

 or rose-red, according to concentration. They are not fluorescent, but 

 show a faint absorption-band, 7-, between b and F, which borders on F, 

 or in greater concentration extends over F. The alkaline solutions are 

 brownish yellow, yellow, or (the ammoniacal) yellowish green, according 

 to concentration. If some zinc-chloride solution is added to an ammoni- 

 acal solution of the pigment it becomes red and shows a beautiful green 

 fluorescence. This solution, as also that made alkaline with fixed alkalies,. 

 shows a darker and more sharply defined band, d, between b and F r 

 almost midway between E and F. If a sufficiently concentrated solution 

 of urobilin alkali is carefully acidified with sulphuric acid it becomes 

 cloudy and shows a s'econd band exactly at E and connected with 7- by a 

 shadow (GARROD and HOPKINS, SAILLET S ). 



Urobilinogen is colorless or is only slightly colored. Like urobilin it 



1 Journ. de Pharm. et Chim., 1878, cited from Maly's Jahresber., 8. 



2 See Salkowski, Berlin, klin. Wochenschr., 1897, and Stokvis, Zeitschr. f. Biologie, 

 34. 



3 Garrod and Hopkins, Journ. of Physiol., 20; Saillet, 1. c. 



