PRACTICAL PHYSIOLOGY. 



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4. Preparation of Haematin (C 32 H 33 N 4 4 Fe). 



(a.) Make defibrinated blood into a paste with potassic carbonate and dry 

 it on a water-bath. Place the paste in a flask, add 4 volumes of alcohol, and 

 boil on a water-bath. Filter, and an alkaline brown solution of hrematin is 

 obtained. Re-extract the residue several times with boiling alcohol, and mix 

 the alcoholic extracts. The solution is dichroic. 



(6.) Acidify the alkaline filtrate of (a.) with dilute sulphuric acid, filter, 

 and keep the filtrate. Observe the spectrum of acid hsematin in the filtrate 

 (figs. 28, 5, and 33, 5). 



A a 



FIG. 33. Spectra of some of the Derivatives of Haemoglobin, i. Haematin in alkaline 

 solution; 2. The same, but more concentrated ; 3. Hsemochromogen ; 4. Methaemo- 

 globin ; 5. Acid hsematin (acetic acid) ; 6. Acid hsematin in ethereal solution. 



(c.) Add excess of ammonia to the acid filtrate of (ft.), and filter off the pre- 

 cipitate, keep the filtrate, and observe that it is dichroic. Observe the 

 spectrum of alkali hrematin in the filtrate (fig. 28, 6). 



(rf.) Evaporate the filtrate from (<:.) to dryness on a water-bath. Extract 

 the residue with boiling water. The black residue is washed on a filter with 

 distilled water, alcohol, and ether, and dried in a hot chamber at 120 C. 

 This is nearly pure hsematin. 



(ft.) It is convenient to keep in stock hfematin prepared as follows :- Ex- 

 tract defibrinated blood or blood-clot 'ox or sheep) with rectified spirit con- 

 taining pure sulphuric acid (i : 20.) Filter ; the solution gives the spectrum 

 of acid haematin. Add an equal volume of water and then chloroform. The 

 chloroform becomes brown, and there is a precipitate of proteids. Separate 

 the chloroform extract, wash it with water to remove the acid. Separate the 

 chloroform, and allow it to evaporate. The dark brown residue is impure 

 h.T-matin. When dissolved in alcohol and caustic soda it gives the spectrum 

 of alkali mematin, and on adding ammonium sulphide that of bemochromogen. 

 If it is dissolved in HoS0 4 , and filtered through asbestos, the red filtrate gives 

 the spectrum of hsemato-porphyrin (MacMunn). 



