50 CHLOROPHYLL. [CH. II 



tube is by displacement of the air, which is allowed to 

 leave the tube by a small gap purposely left uncemented 

 between the leaf and the cork, and which can be closed 

 when the air has been replaced by C0 2 . 



SECTION C. Reactions of chlorophyll and of 

 some other pigments. 



To study the simpler reactions of chlorophyll we 

 extract the green colour of leaves by means of alcohol. 

 The leaves 1 are boiled for a few minutes in water, roughly 

 dried with filter-paper and placed in alcohol. The ex- 

 traction must go on in the dark, because light has a 

 destructive action on the colouring matters. 



(55) Separation by Benzol, etc. 



Place some of the alcoholic extract in a test-tube, 

 dilute it with a few drops of distilled water ; add benzol, 

 shake the mixture, and allow it to settle. The benzol 

 which floats above the alcohol is of a bright greenish 

 blue, while the alcohol dissolves the yellow pigment 

 which forms part of the alcoholic leaf-extract. 



A similar separation may be effected by adding to the 

 alcoholic extract : (a) Ether. (6) Olive oil. 



(56) Action of light*. 



Fill three test-tubes with alcoholic leaf-extract, cork 

 them and place A in sunlight, B in diffused light, C 

 in the dark. After a few hours note the changes in 



1 Almost any leaves will serve the purpose : grass answers well. 



2 Sachs Bot. Zeitung, 1864; Physiologie (French Trans.), 1868, p. 13; 

 "Wiesner, Sitz. Wien. Akad. Vol. LXIX. 1874. 



