PHYSIOLOGICAL CHEMISTEY 349 



ciently, and examined spectroscopically, it will present a spectrum 

 characterised by one band on the red, the wave-length corresponding 

 approximately to A. 645. The blue end of the spectrum will be very 

 largely absorbed (Spectrum 6 in Chart). 



There is frequently a considerable amount of general absorption in 

 the acid-haematin prepared as above, and the band referred to may 

 only be made clear by filtering the solution. More satisfactory results 

 are obtained by extracting the colouring matter with ether, or treating 

 with chloroform and excess of acetic acid, as follows : 



(a) Take defibrinated blood, and add about half its volume of glacial 

 acetic acid and about an equal quantity of ether. Shake at once. 

 The ether will extract the colouring matter, and, on examining the 

 same spectroscopically, three distinct bands will be seen one on the 

 red similar to that already described, but apparently shifted nearer the 

 D-line (A. 640), one on the green (A, 550), another on the green but 

 nearer the blue (A. 515). A very indistinct band may be seen on the 

 yellow (A. 590) (Spectrum 7 in Chart). 



(b) Take defibrinated blood, warm and add half its volume of glacial 

 acetic acid. Cool and add half the volume of chloroform, and more 

 acetic acid if any precipitate appears. The solution will become clear 

 and give a spectrum similar to that shown in the ethereal extract. 



6. The visible Spectrum of Alkaline Haematin. Take some diluted 

 defibrinated blood, and add a few drops of strong caustic soda, and 

 warm. The colour will change to a greenish-brown tint, and when the 

 solution is examined spectroscopically, it will show a single band on the 

 orange (wave-length, A, 600). A more satisfactory method of preparing 

 the alkaline haematin is to form a paste of potassium carbonate and 

 defibrinated blood ; dry it over a water-bath and extract with alcohol, 

 when a reddish-brown solution is obtained which shows the distinguish- 

 ing absorption band clearly (Spectrum 8 in Chart). 



7. The visible Spectrum of Haemochromogen (reduced Haematin). 

 If a watery solution of alkaline haematin be warmed with a few drops of 

 ammonium sulphide, the brownish colour is replaced by a more marked 

 red. If the solution be examined spectroscopically, the one band of 

 alkaline haematin is found to be replaced by two bands on the green, 

 the wave-lengths of their centres being approximately A, 557 and A 525 

 (Spectrum 9). 



8. The visible Spectrum of Haematoporphyrin. Take some strong 

 sulphuric acid (10 c.c.) in a test tube and add a few drops of blood, and 

 shake up the mixture. A purple colour will result, due to the decom- 

 position of the haemoglobin and the formation of the iron-free pigment, 

 haematoporphyrin. This examined spectroscopically will, in the above 



