VI.] 



THE COLOURED BLOOD CORPUSCLES 



13. Acid-Haematin in Ethereal Solution. 



(a.) To undiluted defibrinated blood add glacial acetic acid, 

 which makes the mixture brown. Extract with ether, shake 

 vigorously, and a dark-brown ethereal solution of haematin is 

 obtained. Pour it off and 



(ft.) Observe the spectrum of this solution four absorption 

 bands are obtained. The one in the red between C and D, corre- 

 sponding to the watery acid-hsematin solution; and on diluting 

 further with ether a narrow faint one near D, one between I) and 

 E, and a fourth between ft and F (fig. 28, 5). The last three 

 bands are seen only in ethereal solutions, and require to be looked 

 for with care. 



14. V. Alkali-Hsematin. 



(a.) To diluted blood add a drop or two of solution of caustic 

 potash, and warm gently. The colour changes to a brownish-green, 

 and the solution is dichroic. Or use a solution of acid-hsematin ; 

 neutralise it with caustic soda until there is a precipitate of 

 haematin ; on adding more soda and heating gently, the precipitate 

 is re-dissolved, and alkali-hat- matin is formed. 



(ft.) Shake (a.) with air to obtain oxy-alkali-hsematin. Observe 

 its spectrum, one absorption-band just to the red side of the D 

 line. It is much nearer D than that of acid haematin (fig. 28). 

 Much of the blue end of the spectrum is cut off. 



Red. Oral ge. 



Yellow. 



Green. 



Blue. 



bo 

 A a B C D E F 



FiG. 28. Spectra of Derivatives of Haemoglobin. 5. Haematin in ether with sulphuric 

 acid ; 6. Hfematin. in an alkaline solution ; 7. Reduced hscmatm. 



15. Reduced Alkali-Hsematin or Hsemochromogen. 



(.) Add to a solution of alkali-haematin a few drops of ammonium 

 sulphide and warm gently. Note the change of colour = reduced 



