262 The Outline of Science 



they are charged with negative electricity; they pass straight 

 through bodies considered opaque with a sublime indifference 

 to the properties of the body, with the exception of its mere den- 

 sity ; they cause bodies which they strike to shine out in the dark ; 

 they affect a photographic plate ; they render the air a conductor 

 of electricity ; they cause clouds in moist air ; they cause chemical 

 action and have a peculiar physiological action. Who, to-day, 

 shall predict the ultimate service to humanity of the beta-rays 

 from radium!" 



6 



THE ELECTRON THEORY, OR THE NEW VIEW 



OF MATTER 



The Structure of the Atom 



There is general agreement amongst all chemists, physicists, 

 and mathematicians upon the conclusions which we have so far 

 given. We know that the atoms of matter are constantly either 

 spontaneously or under stimulation giving off electrons, or 

 breaking up into electrons ; and they therefore contain electrons. 

 Thus we have now complete proof of the independent existence of 

 atoms and also of electrons. 



When, however, the man of science tries to tell us how 

 electrons compose atoms, he passes from facts to speculation, and 

 very difficult speculation. Take the letter "o" as it is printed on 

 this page. In a little bubble of hydrogen gas no larger than 

 that letter there are trillions of atoms; and they are not packed 

 together, but are circulating as freely as dancers in a ball-room. 

 We are asking the physicist to take one of these minute atoms and 

 tell us how the still smaller electrons are arranged in it. Natur- 

 ally he can only make mental pictures, guesses or hypotheses, 

 which he tries to fit to the facts, and discards when they will 

 not fit. 



At present, after nearly twenty years of critical discussion, 

 there are two chief theories of the structure of the atom. At first 



