294 THE ALLOTKOPISM OF CHLORINE. [MEMOIK XX. 



lated to their hydrogen atom with different degrees of 

 affinity, and that one of them is retained far more loosely 

 than the other. But this would correspond to our ideas 

 of oxygenized water and not of peroxide of hydrogen, 

 and lead us to the conclusion that the solution employed 

 in this Memoir is strictly a solution of chlorine in water. 



XL The decomposition of chlorine-water, when placed 

 in the sunbeam, does not begin at once, but a certain 

 space of time intervenes, during which the chlorine is 

 undergoing its specific change. 



I need quote no further instance of the truth of this 

 than the experiment given in support of the second fact. 

 This is the same phenomenon which takes place when 

 chlorine and hydrogen are exposed together; they do 

 not begin to unite at once, but a certain space of time 

 elapses, during which the preliminary absorption is tak- 

 ing place, and when that is over union begins. 

 * 



On the Relations of Chlorine and Hydrogen. 



We have thus traced the cause of the decomposition 

 of water, in the case before us, to a change impressed on 

 the chlorine by exposure to the rays of the sun. In this 

 decomposition three elementary bodies are involved- 

 chlorine, oxygen, and hydrogen. 



We can therefore reduce the problem under discussion 

 to simple conditions, and study the relations of each of 

 these substances to each other and to the solar rays suc- 

 cessively. 



When a mixture of oxygen and hydrogen gases, in the 

 proportion to form water, is exposed to the most brilliant 

 radiation converged upon it by convex lenses, union does 

 not ensue ; the reason being, as I have shown, that those 

 gases are perfectly transparent to the rays, and do not 

 possess either real or ideal coloration. For the same 

 cause, water exposed alone for any length of time to the 



