x . HJEMOCHROMOGEN 523 



The absorption-bands a and ft of natural and synthetised haemo- 

 chromogen are as follows : 





Natural A567-A547 A532-A518 (Gamgee). 1 



A565-A547 A527-A514 (Hoppe-Seyler). 2 

 Synthetised A565-A545 A530-A510 (Laidlaw). 3 (See p. 524.) 



The third or y-band, also intense, lies in the violet between 

 h and g, A430-A410, with its centre at A420, and corresponds, 

 therefore, exactly with the band of carboxyhaemoglobin (Gamgee). 



v. Zeynek has prepared hsemochromogen by reducing pure haematin 

 with hydrazin-hydrate, which has an advantage, as the decomposition- 

 products of the reducing agent are inert substances : 



H 2 N - NH 2 . H 2 + 2 - N 2 + 3H 2 0. 



By working in an atmosphere of hydrogen he prevented a subsequent 

 oxidation of the haemochromogen. Its ammonium salt is formed 

 according to the equation : 



2(C 32 H 32 FeN 4 4 ) + 2NH 4 = C 64 H 72 Fe 2 N 10 7 + 0. 



From the haematin liberated by peptic digestion and having the formula 

 C 34 H 35 N 5 FeO 5 v. Zeynek prepared an ammonium salt of haemo- 

 chromogen having the probable formula : 



On shaking an alkaline solution of haemochromogen with air 

 it passes into alkaline haematin, when only judged by the visible 

 absorption-spectrum, but Gamgee has shown that such an assump- 

 tion would be altogether wrong, for oxidised haemochromogen 

 shows no band in the violet, the whole of the violet and ultra-violet 

 becoming indeed much clearer than they are with reduced haemo- 

 chromogen. The behaviour of the violet end of the spectrum is 

 therefore exactly contrary to what it is in the case of alkaline hsematin, 

 for in the latter the whole of the violet and ultra-violet are darkened. 

 On reducing oxidised haemochromogen, the band of reduced haemo- 

 chromogen reappears in the violet. 



Haemochromogen differs from haematin, but resembles haemoglobin 

 in being able to combine with carbonic oxide to form carboxy- 

 haemochromogen, according to Hoppe-Seyler 4 and Kiister. 



1 A. Gamgee, Physiol. Chem. 1. Ill (1880). 



2 Hoppe-Seyler, Zeitschr.f. physiol. Chem. 13. 496 (1889). 



3 P. P. Laidlaw, Journ. of Physiol. 31. 467 (1904). 



4 F. Hoppe-Seyler, Zeitschr. f. physiol. Chem. 13. 477 (1889). 



