THE RED BLOOD CORPUSCLES 



869 



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 

 insoluble 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 trans- 

 formed into hcematoporphyrin, which forms a deep purple solution. The 

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



BC 



FIG. 374. Absorption spectra of haemoglobin and its derivatives. 



1. Oxyhaemoglobin. 2. Reduced haemoglobin. 3. Methsemoglobin. 

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

 haematin in rectified spirit. 7. Reduced hsematin. 8. Acid hsematopor- 

 phyrin. 9. Alkaline haematoporphyrin. (From 



)bably C 33 H 32 4 N 4 Fe.OH. Its compounds with acids and alkalies are 

 spoken of as acid and alkaline haematin, and each gives a characteristic 

 absorption spectrum (Fig. 374). The alkaline solutions exhibit one indis- 

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

 band also between C and D but nearer to 0, and resembling somewhat the 

 band presented by methsemoglobin. According to Hoppe-Seyier and 

 Gramgee, perfectly pure solutions of haematin in alkalies are quite unaffected 

 by reducing agents; in the presence of certain foreign matters however, 

 alkaline hsematin, when treated with reducing agents, exhibits a spectrum 

 known as that of reduced alkaline hsematin, which is identical with that of 



