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The Characters of Methaemoglobin are : — 



In acid solution the oxyhaemoglobin bands 

 are weak or invisible. There is a band between C 

 and D, nearer the former. The band of acid 

 haematin is similar in position. It is, however, 

 close to C. 



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 

 oxyhaemoglobin 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 ; ex- 

 amine for the bands of alk-methaemoglobin. 



2. In presence of urobilin. Proceed in the 

 same way. 



3. In presence of bile pigment. Precipitate 

 these by making the solution alkaline with 

 ammonia after adding CaCl^. 



4. In neutral solutions its spectrum is iden- 

 tical with that of haematin in natural solutions 

 (Neubauer and Vogel). Reduced by (NHJ^S, 

 methaemoglobin is changed to reduced haemo- 

 globin and haematin to reduced haematin, the 

 bands of which are easily recognized. 



Urobilin 



Frequently occurs in the urine in jaundice 

 instead of bile pigment, 

 u 



