826 



PHYSIOLOGY 



the solution into an excess of acid a precipitate is obtained which is hsematin. 

 Hsematin forms a powder of bluish-black colour and metallic lustre. It is in- 

 soluble in water, alcohol, or ether, but is slightly soluble in glacial acetic acid 

 and in absolute alcohol. It is easily soluble in concentrated sulphuric acid, 

 but undergoes decomposition, losing its atom of iron and being transformed 

 into Ticematoporphyrin, which forms a deep purple solution. The formula 

 of hsematin has not yet been ascertained with certainty. It is probably 



JBC D 



FIG. 363. Absorption spectra of haemoglobin and its derivatives. 



1. Oxyhsemoglobin. 2. Keduced haemoglobin. 3. Methaemoglobin. 

 4. Alkaline methsemoglobin. 5. Acid hsematin in ether. 6. Alkaline 

 haematin in rectified spirit. 7. Reduced haematin. 8. Acid haematopor- 

 phyrin. 9. Alkaline hsematoporphyrin. (From 



C 33 H 32 4 N 4 Fe.OH. Its compounds with acids and alkalies are spoken of as 

 acid and alkaline hsematin, and each gives a characteristic absorption spec- 

 trum (Fig. 363). The alkaline solutions exhibit one indistinct absorption 

 band between C and D, the acid solutions an absorption band also between C 

 and D but nearer to C, and resembling somewhat the band presented by methse- 

 moglobin. According to Hoppe-Seyler and Gamgee perfectly pure solutions 

 of hsematin in alkalies are quite unaffected by reducing agents ; in the pres- 

 ence of certain foreign matters, however, alkaline hsematin, when treated 

 with reducing agents, exhibits a spectrum known as that of reduced alkaline 

 haematin, which is identical with that of hsemochromogen. The same 



