746 URINE. 



yellow, or (the ammoniacal) yellowish green, according to concentration. 

 They show a dark band 7, which is moved somewhat toward the red 

 end of the spectrum and lies between E and F. The absorption max- 

 imum lies at X = 506-510. If some zinc-chloride solution is added to 

 an ammoniacal solution of the pigment it becomes red and shows a 

 beautiful green fluorescence and gives the same absorption bands. If 

 a sufficiently concentrated solution of urobilin alkali is carefully acidified 

 with sulphuric acid it becomes cloudy and shows a second band exactly 

 at E, and connected with 7 by a shadow (GARROD and HOPKINS, SAILLET 1 ). 

 Urobilinogen is colorless or only faintly colored, but is very quickly 

 changed in the air and by the action of light and is transformed into urobilin. 

 The urobilinogen, which is identical with hemibilirubin, can be obtained 

 as colorless prisms by solution in hot acetic-ether and treating this with 

 ligroin, and evaporating. Urobilinogen is soluble in ether, acetic ether, 

 amyl alcohol and in chloroform, and can in part be removed from the 

 urine after adding sodium bicarbonate and shaking with chloroform 

 (FISCHER and MEYER-BETZ). It can also be obtained directly from the 

 urine or from the acidified urine by shaking with chloroform or ether, 

 although it is less pure. In a chloroform solution of urobilin and urobilino- 

 gen, according to GRiMBERT 2 , only urobilin and not urobilinogen is 

 taken up by a sodium diphosphate solution, which is not colored red by 

 phenolphthalein. Like urobilin, it is precipitated from the urine on 

 saturating with ammonium sulphate. When free from urobilin it does 

 not give any absorption bands and no fluorescence with ammonia and 

 zinc salt. For the detection and identification of urobilinogen we make 

 use of EHRLICH'S reagent (p-dimethylamino-benzaldehyde). This 

 reagent consists of dissolving 2 grams p-dimethylaminobenzaldehyde 

 in 50 cc. concentrated, fuming hydrochloric acid and diluting to 100 

 cc. with water. To 10 cc. of the urine add 1 cc. of the reagent and 

 thoroughly shake. According to the amount of urobilinogen, the solution 

 becomes pink colored or intensely red, and in the spectrum we find a 

 band between D and E. The red color can be taken up by amyl alcohol. 

 Urobilin does not give this reaction, which is common to certain haematin 

 and pyrrol derivatives. 



The preparation of urobilin from the urine can be done according to the 

 original method of JAFFE, or according to the method suggested by MEHU, 

 which has been modified somewhat by GARROD and HOPKINS 3 (precipita- 

 tion with ammonium sulphate) or according to CHARNAS' suggestion. 



According to CHARNAS* the preparation is best from urobilinogen, 



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



2 Fischer and Meyer-Betz, 1. c.; Grimbert, Compt. rend. soc. biol., 70. 

 8 Jaffe\ 1. c.; Me"hu, 1. c.; Garrod and Hopkins, Journ. of Physiol., 20. 

 4 Charnas, Bioch. Zeitschr., 20. 



