254 HEMOGLOBIN. 



The compounds of hsematin with acids, e.g. hsematin-hydrochloride, 

 present, even in solutions of great dilution (1 : 25,000-1 : 50,000), an 

 intense absorption - band, which encroaches more and more on the 

 ultra-violet, as the strength of the solution increases. In a solution con- 

 taining one part of crystallised hgematin. hydrochloride in 20,000 parts 

 of glacial acetic acid, the band extends between h and M, the most 

 intense absorption between h and L. The less refrangible border of this 

 band is sharply defined, whilst the more refrangible border is less 

 definite. As the solution is diluted the band becomes narrower, 

 through less and less of the ultra-violet being absorbed. In highly dilute 

 solutions the band which is still intense absorbs both H and K. 1 



The acid compounds of hsematin exhibit, therefore, an absorption- 

 band, which is exactly on the boundary of the idtra- violet proper, and 

 which extends further and further into the ultra-violet as the con- 

 centration of the solution increases. 



G HK L M NO 



FIG. 37. The photographic spectrum of luemin. 



HJEMOCHROMOGEN (SYN. " KEDUCED H^MATIN "). 



It has already been explained that Hoppe-Seyler employed the 

 name hsemochromogen to denote the very remarkable body which he 

 was the first to study with care, and which results from the decomposi- 

 tion of reduced haemoglobin, in the absence of all oxygen, by acids, and 

 especially by alkalies, and of which the solutions present absorption- 

 bands in the visible spectrum, which are identical with those of the 

 reduced haematin of Stokes. 



The latter name had been applied by Stokes to the chemical 

 substance assumed to be the cause of the characteristic absorption- 

 spectra which are exhibited by solutions of the blood-colouring matter, 

 and likewise by impure solutions of hsematin when subjected to the 

 action of reducing agents. It now remains to describe the methods of 

 preparing solutions of hsemochromogen, the body itself and its properties 

 (so far as these are known to us), its combinations, and especially to 

 refer to the views which Hoppe-Seyler advanced and held, in reference 

 1 Gamgee, Proc, Hoy. Soc. London, 1896, vol. lix. p. 276. 



