THE MICROSCOPE IN CHEMISTRY. 



103 



bands, it is judged that haematocrystalline is present in it 

 as such, and not formed from it. By treating a solution 

 of blood which exhibits the two absorption-bands with 

 hydrogen, or with a solution of ferrous sulphate contain- 

 ing tartaric acid and excess of ammonia, taking care to 



A a B r 



H H" 



Reduced Hsniutocrystalline. 



exclude the air, the color of the solution changes to pur- 

 ple, and the spectroscope shows only one broad band in- 

 stead of two (Fig 57). Shaking with air will restore the 

 two bands. By treating blood with hydrothion or am- 



A n B 



n rr 



Blood treated with Ammonium Sulphide. 



monium sulphide, three bands make their appearance, as 

 in Fig. 58. 



Haematin is seen by the microscope to consist of small 



H w 



Four-banded Hitnuttiu. 



rhombic crystals. Dissolved in alcohol and a little sul- 

 phuric acid, the spectrum shows four, and under some 

 circumstances five, bands (Fig. 59). Rendered alkaline 



