168 THE NEW KNOWLEDGE. 



mon salt Other chemical reactions can be explained in 

 the same way. Chemical affinity is electrical affinity. 



THE INERT ELEMENTS OF THE ZERO GROUP. 



The rare gases of the atmosphere, such as helium, neon 

 and argon, which were a few years ago discovered by the 

 masterly researches of Rayleigh, Ramsay and Travers, and 

 which are now associated together in the zero group of 

 the periodic law, bear out in a most interesting and re- 

 markable way the corpuscular theory we are considering. 

 These gases are alike in this, that they have no combining 

 power, or valency, whatever. They combine chemically with 

 no known element. In our study of corpuscular groupings 

 we found that a group of 59 corpuscles and a group of 67 

 corpuscles were in precisely this position that they were 

 hopelessly unable to retain any electrical charge whatever, 

 that is, unable, permanently, either to lose or to acquire a 

 corpuscle. If, as we have said, chemical action means 

 simply the power either to lose or to acquire corpuscles, it 

 is obvious that atoms built up of such corpuscular groups 

 would be quite unable to enter into chemical combination. 

 They would, therefore, be like helium and neon. Not only 

 so, but these groups occur at the proper intervals. They 

 occur with seven groups in between, just as helium and 

 neon occur with seven atoms in between. 



It is very evident then that if, as we said in Part II, the 

 rare gases of the atmosphere have found a home in the 

 periodic law, they have also found a home in the corpus- 

 cular theory which explains that law. 



RADIO-ACTIVITY AND THE EXISTENCE OF UNSTABLE ATOMS. 



But the corpuscular theory of the atom must explain 

 the transmutation of matter as it is seen to take place in 



