CHAP. II.] 



THE BLOOD. 



115 



layers possess a fine red colour and absorb strongly, as is proved by 

 spectrum analysis, not only the violet rays, but also the yellow 

 between Frauenhofer's lines C and D, especially near the latter. If 

 alkaline solutions of haematin of sufficient dilution be examined, a 

 distinct absorption band, the centre of which corresponds approxi- 

 mately to wave-length 603, is observed. 



Haematin dissolves sparingly in alcohol holding sulphuric acid in 

 solution, the solution assuming a dark-brown colouration. 



Action of When heated with fuming hydrochloric acid to 160C., 



hot HC1 on the iron which haematin contains is removed from it, and 



is found in the solution as a ferrous salt, whilst a body free 

 from, iron, termed Haematoporphyrin, is formed. Alkaline solutions of 

 haematin, if pure, are not attacked by reducing agents. If, however, 

 organic matters, such as proteids, be present, haemochromogen (syn. reduced 

 haematin) is formed l . Haematin is scarcely, if at all, affected by putrefactive 

 processes. (Hoppe-Seyler.) 



When potassium cyanide is added to an ammoniacal 

 solution of pure haematin, or to a solution of oxy-haemo- 

 globin, a broad band somewhat resembling that of reduced 

 haemoglobin, though by no means identical with it, is pro- 

 duced. This band extends from D to E. On adding reducing agents a 

 spectrum with two well-marked absorption bands is obtained. These optical 

 characters are supposed to depend upon the production of a compound 

 of haematiii and the cyanide employed, which has been denominated cyan- 

 haematin. We are, however, merely acquainted with the spectroscopic 

 characters of the supposed compound. 



Action of 

 Potassium 

 Cyanide on 



haematin. 



Mode of 

 preparing 

 crystals of 

 Haemin for 

 microscopic 

 examination. 



Hydrochlorate of Haematin Haemin. 



When a small drop of blood is boiled with a few drops 

 of glacial acetic acid, the red colour almost instantly gives 

 place to a brownish colouration. On evaporating down 

 the fluid a residue is obtained, which on microscopic 

 examination is found to be composed of reddish-brown 



Fm. 24. CRYSTALS OF HAEMIN. (Frey.) 



1 Hoppe-Seyler, " Weitere Mittheilungen iiber die Eigenschaften des BlutfarbstofFs." 

 Zeitschrift f. phys. Chemie. Vol. n. (1878) p. 154. 



82 



