114 PEEPAKATION AND PKOPERTIES OF HAEMATIN. [BOOK I. 



is a simple product of decomposition, which can be formed from re- 

 duced haemoglobin in the absence of oxygen. 



Methods of I. Blood (defibrinated) is mixed with ether and then a 



preparation large quantity of strong acetic acid is added ; the two 

 ofHaematin. liquids are thoroughly shaken, and thereafter the dark- 

 brown ethereal solution is decanted, filtered and set aside. The deposit 

 which separates is washed with ether, alcohol, and water. 



II. Blood is coagulated by the addition of an excess of cold alcohol ; 

 the precipitate is separated and boiled with alcohol holding sulphuric acid 

 in solution. The hot filtered solution is set aside, and the matter which 

 separates and adheres to the glass is washed with water and then with 

 alcohol, and ether. 



Although the above methods may yield haematin with which some 

 qualitative experiments may be tried, we must employ the next process 

 if it be desired to obtain the pure substance, viz. : 



III. Crystals of Hydrochlorate of Haematin or Haemin are dissolved 

 in exceedingly dilute solution of pure potassium hydrate; the filtered solution 

 is neutralized with hydrochloric acid, which throws down haematin in the 

 form of a flocculent brown precipitate, which is washed with boiling water, 

 until the washings are no longer rendered turbid by solution of silver 

 nitrate. The haematin is then collected and dried, first at a gentle heat, 

 and then at 120 150 C. (Hoppe-Seyler 1 .) 



Properties Haematin, obtained by the method last mentioned, 



of fcaematin. ^ as a blue-black colour and a decided metallic lustre; it 

 is free from crystalline structure, and when pulverized yields a dark- 

 brown powder. 



It can be heated to 180C. without undergoing decomposition, but 

 when heated more strongly it burns, evolving hydrocyanic acid, and 

 leaving an ash which consists of pure oxide of iron, amounting to 

 12 - 6 per cent. 



The following is the mean percentage composition of pure hae- 

 matin, as determined by Hoppe-Seyler: 



Carbon ........................ 64'30 



Hydrogen ..................... 5*50 



Nitrogen ..................... 9'06 



Iron ........................... 8-82 



Oxygen ........................ 12-32 



100-00 



These numbers agree well with the formula 



Haematin is insoluble in water, alcohol, and ether, easily soluble 

 in solutions of the caustic alkalies, if these are not too concentrated, 

 insoluble in diluted acids, and soluble with difficulty in hot alcohol 

 holding sulphuric acid in solution. 



Watery or alcoholic alkaline solutions of haematin when examined 

 in thin layers by reflected light possess an olive-green colour; deeper 



1 Hoppe-Seyler, "Beitrage zur Kenntniss des Blutes des Menscheu und der 

 Wirbelthiere. Das Haematin." Med. Chem. Untersuchungen, Heft iv. 1871, p. 523. . 



