522 CHEMISTRY OF THE PROTEIDS CHAP. 



The synthesis of hsematin out of hsematoporphyrin. and a ferrous 

 salt by Laidlaw's method is described on p. 524. 



Arnold l has described a ' neutral hsematin ' which dissolves in 

 neutral dilute alcohol containing salts, and which possesses a spectrum 

 resembling that of oxyhsemoglobin. The existence of this substance 

 has, however, been denied. 2 



Hsematin is magnetic, and thus differs from the diamagnetic oxy- 

 hsemoglobin (Gamgee). 3 



Linossier 4 has described a nitrous oxide-hsematiri, the spectrum of 

 which corresponds to that of NO-hsemoglobin, and which could not be 

 reduced ; by oxygen it is split up into hsematin and nitrous oxide. 



Cyanhsematin has been described on p. 505, along with cyan- 

 methsemoglobin. 



Haemochromogen 



It is generally stated that Hoppe-Seyler succeeded in getting 

 hsemochromogen to crystallise, but this statement, according to 

 Gamgee, 5 is erroneous. Donogany, 6 by acting on blood with pyridin 

 and ammonium sulphide, did obtain crystals, and Robert 7 succeeded 

 by the same method. Hsemochromogen has the appearance of 

 powdered red phosphorus ; on being dried more thoroughly it 

 becomes reddish-brown, and in the moist state has to be carefully 

 protected against air, as otherwise it is converted into hsematin. It is 

 insoluble in water, alcohol, and ether, but readily soluble, with a 

 cherry -red colour, in alkalies; it is precipitated by neutralisation, 

 v. Zeynek supposes that it is formed by one atom of oxygen being 

 removed from two molecules of haematin ; its ammonia salt has accord- 

 ing to him the formula : 



C 64 H 70 Fe 2 N 10 7 . 



Hsemochromogen shows three absorption-bands! The a-band lies 

 between D and E, nearer D with its centre at A559 (v. Zeynek); the 

 second or /3-band commences at E and extends beyond b. The first 

 band is especially intense. 



1 V. Arnold, Zeitschr. f. physiol. Chem. 29. 78 (1900). 



2 K. H. L. van Klaveren, ibid. 33. 293 (1901) ; Maly's Jahresb.f. Tierchem. 30. 

 164 and 165 (1900) (V. Arnold and L. Wachholz). 



3 A. Gamgee, Proc. Roy. Soc. 68. 503 (1902). 



4 G. Linossier, Compt. Rend. 104- 1296 [according to Maly's Jahresberichte, 17- 

 121 (1887)]. 



5 A. Gamgee, Schafer's Textbook, 1. 256 (1898). 



6 J. Donogany, Maly's Jahresberichte, 1893, pp. 126-131; Virchows Arch. 148. 234. 



7 H. U. Robert, Zeitschr. f. angew. Microskop. 5. Heft 6-10 (1900) ; and Reprint, 

 P. Wittrin, Leipzig, 1900. 



