PART III. 

 GASEOUS IONS. 



CHAPTER I. 



GASES FROM THE STANDPOINT OF PHYSICS: How THEY 

 CONDUCT ELECTRICITY. 



In the foregoing pages an attempt has been made to 

 show above everything else the necessity of finding some 

 one thing to explain our explanations. We have learned 

 that there is a strange law that binds together the diverse 

 elements of matter; and this law has led us to the very 

 reasonable conclusion that the atoms of matter are com- 

 posite particles, built up of particles smaller still, and that 

 the atoms, as we know them, have probably undergone 

 some form of evolution from simpler conditions. 



But we have no positive proof of this. It is simply a 

 reasonable hypothesis, based upon observed facts; and, 

 moreover, even if we actually had this proof we should 

 not be able to explain the meaning of the periodic law 

 and the mystery of matter. The One Thing is missing; 

 and while the chemist may tell us of a certain search he 

 has, he cannot give us the actual touchstone of truth that 

 we demand. We must, therefore, abandon the chemist 

 to his retorts and crucibles, his burettes and condensers, 

 and betake ourselves elsewhere. Preferably, we should go 

 to the laboratory of the physicist. 



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