CH XII.] UROBILIN. 279 



It is soluble in amyl alcohol. Solutions have a reddish 

 colour, but are unstable to light. 



The pigment is usually associated with the urates or 

 uric acid of the urine. 



Haematoporphyrin is found in traces in normal urine. 

 There is a certain increase in fevers, and some other 

 diseases, but a very marked increase in certain cases of 

 poisoning by sulphonal or trional, especially in women. 



Urorosein occurs in urine as a chromogen which is 

 converted into the pigment by the action of strong acids, 

 such as hydrochloric and sulphuric. 



It is insoluble in ether and is thus distinguished from 

 indigo blue formed in the test for indican. (Ex. 318.) 



The chromogen seems to be an indol body, possibly 

 indol-acetic acid. 



323. Note the colour of normal urine and examine some in a 

 beaker by the spectroscope. Note that there are no definite ab- 

 sorption bands, but a general absorption of the violet. Urochrome, 

 the chief urinary pigment, yields no bands. 



324. Saturate at least 200 cc. of urine with ammonium 

 sulphate. Filter off the precipitate and let it dry completely in the 

 air. Extract it with a small amount of strong alcohol. A brownish 

 solution containing urobilinogen is obtained. Treat this with a few 

 drops of hydrochloric acid : the urobilinogen is converted to 

 urobilin. Examine with the spectroscope, and note a single 

 absorption band situated at the junction of the blue and the green. 

 Its centre is about A 490. 



325. Bogomolow's test for urobilin or urobilinogen. Treat 

 10 cc. of the urine with 10 drops of 20 per cent, copper sulphate. 

 Add about 4 cc. of chloroform, place the thumb on top of the tube 

 and invert 10 times without shaking. If abnormal amounts of 

 urobilin or urobilinogen are present, the chloroform layer is coloured 

 yellow. 



Place the finger on the upper end of a dry 5 cc. pipette and 

 insert the lower end into the chloroform layer. Suck up the chloro- 



