CHEMICAL PARADOXES. 



2. Disintegration in General. 



The process of disintegration is not a simple 

 one ; not only do some of the groups of corpuscles 

 thrown off by the disintegrating atom of radium 

 develop into atoms of helium, but the part 

 left behind undergoes further development 

 through various stages, producing various sub- 

 stances of which lead appears to be the most 

 stable. Earlier still in its own history radium 

 appears to be a product of the disintegration of 

 uranium. Here we have not only four separate 

 elements connected by transmutation changes, 

 but a remarkable instance of the prevalence of 

 the process of disintegration. 



Further examination has shown that, be- 

 sides the other recognised radio-active sub- 

 stances, uranium, thorium, polonium, and ac- 

 tinium, which are undergoing changes of the 

 same nature as radium, and besides the others 

 of a similar character which are being or are 

 to be discovered, many well-known substances 

 show, on very careful examination, that they 

 are capable, though in a much less degree, of the 

 same manifestations as radium, and therefore 

 are undergoing similar degradation changes. 

 Mercury and copper show decided evidence of 

 this character, and as the delicacy of observa- 

 tion has increased it appears to have been prac- 

 tically proved that, though they vary in the 

 degree of their radio-activity, none of the 



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