50 CHLOROPHYLL. [CH. II 



tube. The wire-gauze serves to prevent the leaf bulging 

 inwards into the tube. The best method of filling the 

 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 when the air has been replaced by COo. 



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^ 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. 

 (h) Olive oil. 



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



