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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 CaCU 
4. In neutral solutions its spectrum is identical 
with that of haematin in natural solutions (Neubauer 
and Vogel). Reduced by (NH 4 ) 2 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- 
moglobinaemia. 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. 
