142 A. Pedler — Bleaching action of light on colouring matters. [No. 2 T 



sets of experiments were tried in which coloured substances were 

 exposed to the action of sunlight after being moistened with water, 

 and the bleaching under these circumstances compared with that 

 produced by sunlight when the coloured bodies were kept free from 

 water and only exposed to moist air. In all cases the presence of 

 evaporating water rendered the bleaching much more rapid. 



It will be seen that in the above list, A to G inclusive, no less than 

 97 experiments were started, and in addition to these a good many 

 others were made, which are not reproduced in detail. Each experi- 

 ment was examined every few days at first, and later on every few 

 weeks, and the condition of the specimens was compared with freshly 

 prepared specimens when necessary, and the results carefully recorded. 

 Hence a large mass of facts was obtained. It will be seen that it 

 would be impossible to describe the detailed results of each individual 

 experiment, as this would take a large amount of space, nor indeed are 

 the results of sufficient value to make the publication of the details 

 necessary. Hence the main results only of the experiments are sum- 

 marised in seven tables, A to Gr, which are printed below. 



It may be convenient here to explain that the comparative results 

 shown in tables A and B, are intended to differentiate between the 

 causes referred to in 4 previously. The comparison of the results in 

 B and C, is intended to differentiate between the causes referred to in 

 1 and 2. The comparison of the results given in D and E, and given in 

 ¥ and G, is again intended to differentiate between the causes referred 

 to in 1 and 2, and finally the results of D and E together, compared 

 with those of F and G together, will enable a conclusion to be obtained 

 with reference to cause 3. 



