229 



In alkaline solution the acid band disappears, and 

 a faint band on the red side of D takes its place (compare 

 with alkaline haematin). 



Reduced by ammonium sulphide, the bands of 

 reduced haemoglobin are got. It differs from oxyhae- 

 moglobin in its chemical reactions by the fact that it 

 is precipitated by basic or neutral lead acetate solution, 

 whereas oxyhaemoglobin is not. 



Detection : 



1. In presence of oxyhaemoglobin. Ppt. with 

 basic lead acetate ; filter, decompose the precipitate 

 with carbonate of soda solution ; examine for the bands 

 of alk-methaemoglobin. 



2. In presence of urobilin. Proceed in the same 

 way. 



3. In presence of bile pigments. Precipitate 

 these by making the solution alkaline with ammonia 

 after adding CaCL,. 



4. In neutral solutions its spectrum is identical 

 with that of haematin in natural solutions (Neubauer 

 and Vogel). Reduced by (NH 4 ),S, methaemoglobin 

 is changed to reduced haemoglobin and haematin to 

 reduced haematin, the bands of which are easily recog- 

 nized. 



UROBILIN 



Frequently occurs in the urine in jaundice 

 instead of bile pigment. 



According to Hayem, it is associated with methae- 

 rnoglobinaemia. Its occurrence in blackwater fever 

 is very common, occasionally before the attacks, but 

 more constantly after the oxyhaemoglobin has dis- 

 appeared or together with it. 



