Manchester Memoirs, Vol. Hi. {igo^), No. 14. 19 



The precise character of the change which chloride of 

 Hme solutions undergo in presence of light was not 

 studied, but, in view of the experiments of Fedler* and of 

 Richardson*!", it would appear most probable that calcium 

 chlorate is formed. 



The Effect of Sunlight on Chloride of Silver, etc. 



It was thought possible that, in the intensely active 

 sunlight of Calcutta, chloride of silver and other substances 

 might suffer molecular change to a greater degree than 

 had hitherto been observed. Accordingly an old experi- 

 ment suggested by Abney was repeated. Well washed 

 silver chloride was dried on the water-bath and sealed up 

 in a glass tube, in one case alone, in the other case with 

 a small globule of mercury, and exposed to light. 

 Darkening took place in both cases, and on placing in 

 darkness, the silver chloride in the tube without mercury 

 became completely white again, while in presence of 

 mercury the darkening persisted. This difference in 

 effect appeared to continue indefinitely, however long the 

 exposure to light, or however frequent the intervals of 

 darkness. It would appear, therefore, that light is 

 incapable of so far modifying the chloride of silver as to 

 render it incapable of taking up in the dark the chlorine 

 lost in the light, while on the other hand, in presence of 

 mercury, it was not possible to say that a definite limit to 

 decomposition had been reached. These results would 

 favour the supposition that the darkening of silver 

 chloride in light is due to a simple dissociation effect, 

 rather than to the formation of an oxychloride. 



•"The Action of Chlorine on Water in the Light, and the Action of 

 Light on certain Chlorine Acids." Ah^xander Pedler, Y.\.(2., Joicfn, Chem. 

 Soc. Trans. LVIL, 1890, p. 613. 



t " The Reaction between Calcium Carbonate and Chlorine Water." 

 Arthur Richardson, Y\\.Y).,Journ Chem. Soc. Trans. XCIIL, 1908, p. 280. 



