402 



Mr. H. Wager. 



it occurred to me that similar effects might be brought about in the dark by 

 the use of some of the ordinary agents such as hydrogen peroxide and 

 permanganate of potash. I accordingly placed chlorophyll films, obtained 

 by the evaporation of a petroleum ether solution of grass chlorophyll, in 

 contact with a very dilute solution (pink) of permanganate of potash. These 

 were allowed to act for six days and were then examined. In all cases the 

 chlorophyll films showed considerable bleaching, and on carefully washing 

 them with water to get rid of the oxidising agents and then bringing them 

 into contact with Schiff's solution, a pronounced pink coloration was pro- 

 duced, showing the presence of an aldehyde. The aldehyde at first appeared 

 in the film, but the colour soon became dissolved in the Schiff's solution, 

 leaving a thin white layer in the glass. The powerful oxidising solution 

 made by adding a few drops of sulphuric acid to a dilute solution of perman- 

 ganate of potash acts very rapidly in bringing about the oxidation of 

 chlorophyll and the production of an aldehyde. A film of chlorophyll placed 

 in contact with the solution began to bleach at once, and in half an hour gave 

 a very pronounced reaction with Schiff's solution. 



The following experiments were also tried : A film of grass chlorophyll 

 placed in the dark in contact with a 20-per-cent. solution of hydrogen 

 peroxide for 16 days and then washed in water gave a strong reaction with 

 Schiff's solution. The pink colour was first of all developed in the film, 

 but soon became washed out in the solution, leaving a whitish layer on the 

 glass. 



A film of the yellow colouring matter of chlorophyll was treated in the 

 same way, and gave a similar reaction with Schiff's solution. 



A film of the green colouring matter of chlorophyll, treated in the same 

 way, showed very slight decoloration or bleaching, and gave no reaction 

 with Schiff's solution. 



Similar results were obtained when strips of paper tinged with chlorophyll 

 were used. 



The bleaching of chlorophyll in the presence of hydrogen peroxide takes 

 place much more rapidly in the light than in the dark. Thus, a film of 

 grass chlorophyll was completely bleached in 12 hours in the light, but a 

 similar film was hardly changed after ten days in hydrogen peroxide in the 

 dark. In bright sunlight, complete bleaching was effected in three hours. 



The film which had been bleached in the light gave a very strong reaction 

 for aldehyde, and the oxidation of the film was so complete that only a 

 trace of white film was left on the glass after the aldehyde had been 

 dissolved out by the Schiff's solution. 



The dilute sulphuric acid solution of permanganate of potash is a much 



