eg. II] CHLOROPHYLL. 43 



the leaf, the mercury rises iii the tube. The wire 

 gauze serves to prevent the leaf bulging inwards into the 

 tube. The best method of filling the tube is by displace- 

 ment 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 been replaced by CO2. 



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 (cyanophyll) while the alcohol dissolves the yellow 

 pigment (xanthophyll) which forms part of the alcoholic 

 leaf-extract. 



A similar separation may be effected by adding to the 

 alcoholic extract : — 

 (a) Ether. 

 (&) Olive oil. 



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



