184 Alfred J. Eivart: 



The influenct of ttmptratart. 



Thin, bright green chlorophyll films formed on the floor of a 

 beaker kept on a boiling water bath rapidly turned bright yellow, 

 After twenty-four liours in darkness on the water bath, the films 

 were nearly colourless. Comparative tests showed that although 

 the bleaching of chlorophyll by oxidation at 100°C. is rapid, it is 

 not as rapid as in sunlight at 30-35°C. 



Films prepared from a petrol ether solution separated from an 

 alcoholic solution, to which copper sulphate had been added, 

 remained green after an hour on the boiling water bath, and still 

 showed colour after twenty-four hours. The copper compound with 

 chlorophyll is therefore more resistant than chlorophyll, not only 

 to photo-oxidation, but also to thermo-oxidation. 



Chlorophyll films in large sealed tubes filled with carbon dioxide 

 kept at 100 ''C, Avithin one to two hours became bright yellow. 

 The petrol ether extract was dark yellowish in colour, showed a 

 strong fluorescence, and gave the spectrum of phaeophytin. It 

 ^uelded no appreciable ash. Apparently at high temperatures car- 

 bon dioxide acts readily on chlorophyll, removing its magnesium 

 and producing phaeophytin. 



The photo-oxidation of xanthophyll. 



In a previous paper it was suggested that portion of the oxygen 

 produced during the interaction of carbon dioxide with chlorophyll 

 might he used to oxidise xanthophyll into phytol, hexose sugars and 

 formaldehyde. This suggestion was based upon data obtained by 

 passing moist oxygen over dry " xanthophyll " films in tubes 

 exposed to light. Further experiments carried out with films 

 exposed to light under water kept saturated with air gave no 

 trace of formaldehyde on distilling the oxidised liquid. The 

 method of obtaining the xanthophyll used in these experiments 

 yields a product which though free from chlorophyll, contains a 

 high proportion of xanthophylloid and other impurities. 



Owing to their presence, the impure " xanthophyll " obtained as 

 previously described is temporarily soluble in petrol ether. Films 

 from petrol ether solutions were covered with water exposed to sun- 

 light and frequently shaken with fresh air, until the film breaks up 

 to form a white, milky liquid. In addition strong alcoholic solu- 

 tions were poured into water and similarly exposed. The products 

 in this case are the same, but the bleaching is more rapid. 



