372 PHYSIOLOGICAL CHEMISTRY. 



with ammonium sulphate by the addition of sulphuric acid 

 (MEHY). It is soluble in alkalies and is incompletely 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 

 alkaline solutions of urobilin give insoluble combinations with salts 

 of the heavy metals, such as zinc and lead. Urobilin does not give 

 GMELIN'S test for bile-pigments. 



Neutral 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, 

 according to concentration, brown, reddish yellow, or rose-red. 

 They are not fluorescent, but show a faint absorption-band, y, 

 between b and F, which borders on F, or in greater concentration 

 extends over F. The alkaline solutions are, according to concen- 

 tration, brownish yellow, yellow, or (the ammoniacal) yellowish 

 green. If some zinc-chloride solution is added to an ammoniacal 

 solution, 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, tf, almost midway between 

 b and F. 



The urobilin obtained by MAcMuNN according to other 

 methods, and that obtained by JAFFE, differ from each other 

 mainly in the following: A solution of normal urobilin becomes 

 deeper red with soda, while the febrile urobilin becomes yellow. 

 The band y of the normal urobilin disappears on the addition of 

 alkali, while the corresponding band of the febrile moves towards 

 the left. The ethereal solution of febrile urobilin shows two faint 

 absorption-bands on each side of D which are not to be seen in the 

 watery solution nor in the urine. Febrile urobilin is a brownish- 

 red and the normal a yellowish-brown powder. Febrile urobilin is, 

 according to MAcMuNK, converted into normal urobilin by po- 

 tassium permanganate. 



In preparing urobilin from normal urine, precipitate the urine 

 with basic lead acetate (JAFFE), wash the precipitate with water, 

 dry at the ordinary temperature, then boil it with alcohol, and 

 decompose it when cold with alcohol containing sulphuric acid. 

 The filtered alcoholic solution is diluted with water, saturated with 



