THE COLOURED BLOOD-CORPUSCLES. 



35 



adding more soda, and heating gently, the precipitate is re- 

 dissolved and alkali-hsematin is formed. Or to diluted blood 

 add a drop or two of solution of caustic potash, and warm 

 gently. The colour changes, and the solution is dichroic. 



90 



111 IU jlLII j 

 100 110 



Fig. 5. Spectra of Derivatives of Haemoglobin. 5, Hsematin in alcohol 

 with sulphuric acid ; 6, hsematin in an alkaline solution ; 7, reduced 

 heematin. 



(b.) Shake (a.) with air to obtain oxy-alkali-haematin. 

 Observe its spectrum, one absorption band just to the red 

 side of the D line. It is much nearer D than that of acid- 

 hsematin (Fig. 5, 6). Much of the blue end of the spectrum 

 is cut off. 



14. Reduced Alkali-haematin or Haemo-chromogen. 



(a.) Add to 13, V. (b.) a drop or two of ammonium sulphide 

 and warm gently = reduced alkali-hsematin, Stokes's reduced 

 hsematin, or hgemo-chromogen, and observe its spectrum ; 

 two absorption bands between D and E, as with HbO 2 and 

 HbCO, but they are nearer the violet end. The first band 

 to the violet side of the D line is well-defined, while the 

 second band still nearer the violet end (in fact it nearly 

 coincides with the E line) is less defined. They disappear 

 on shaking vigorously with air, and reappear on standing, 

 provided sufficient ammonium sulphide be added. 



