SOME ASPECTS OF THE ATOMIC THEORY 583 



is probably present in too small proportion to account for the 

 discrepancy in the atomic weight. 



Around the views taken of the electron, the atom of negative 

 electricity divorced from matter, the greatest divergence of 

 opinion will probably be found. It possesses inertia or mass, 

 but it is yet unknown whether it possesses weight and, if so, 

 whether the ratio of mass to weight is the same for electricity as 

 for matter. Can it in any sense be reasonably regarded as one 

 of the primordial atoms of matter out of which Prout, and others 

 who have followed him, regarded all atoms as built up ? We 

 read, " Since the electron can be got from all the chemical 

 elements, we may conclude that electrons are a constituent of all 

 the atoms. We have thus made the first step towards a know- 

 ledge of the structure of the atom and towards the goal towards 

 which since the time of Prout many chemists have been striving, 

 the proof that the atoms of the chemical elements are all built up 

 of simpler atoms — primordial atoms, as they have been called." 

 There has been, of course, abundant evidence ever since the 

 work of Faraday on electrolysis in liquids that electric charges 

 are associated with the atoms of matter, and play a vital part in 

 chemical changes. 



The above reasoning might be, and has indeed been mistakenly 

 used to show that hydrogen is a common constituent of all 

 matter, since, whatever the matter you may put into a vacuum 

 tube, hydrogen is always obtained from it by the electric dis- 

 charge. Yet a billion atoms of hydrogen would be difficult to 

 detect, whereas a dozen or so electrons are ample for detection. 

 The use of these refined experimental methods carries with it 

 the necessity of not seeming to draw such simple conclusions. 

 Not that the conclusion is not probably correct, but the evidence 

 here alleged in its support is worthless. 



The withdrawal of an electron from the hydrogen atom 

 results in the well-known hydrogen ion, the material particle 

 which confers upon a whole class of substances the common 

 quality of being acids. The hydrogen ion is at once the simplest 

 atom of matter known, and yet according to present views 

 it does not contain a single electron ! The a-particle expelled 

 in radioactive changes is the helium ion, the second simplest 

 atom of matter known, and again it does not contain a single 

 electron. If it were necessary to resuscitate Prout's rather 

 obvious hypothesis as to the constitution of matter it would 



