filtered, it loses this increased conductivity. Thus something is 

 filtered from the gas, which gave it conductivity. This something can 

 also be taken from the gas by passing it through a space in which 

 there is a current of electricity. Only particles could be caught in a 

 filter and only electrified particles would be drawn from the gas by 

 a current of electricity. As the gas, as a whole, does not change, the 

 particles must be both positive and negative. Once having discovered 

 these particles, the scientist experiments with them. He subjects them 

 to electrical forces and by their motions determines their charge, 

 velocity and weight by the familiar formulae of Physics. He finds 

 them one-thousand times smaller than the smallest atom; alike in 

 nature and size and that they constitute an actual part of the matter 

 from which they fly. He controls them so as to produce chemical, 

 heating and mechanical effects and thus arrives at a more intimate 

 knowledge of them. He finds that they give rise to x-rays in bodies 

 which they strike; that they are absorbed by all bodies in direct 

 proportion to the density of those bodies; and that they act as nuclei 

 about which atoms and molecules collect. These corpuscles are given 

 off by elements in their natural state, by radium, uranium, polonium, 

 actinium, air, etc. As these different substances continually emit these 

 particles, one-thousand times smaller than atoms, it is reasonable to 

 believe the atoms constituted of them. This belief is strengthened 

 when we find that, as the corpuscles are emitted by some substance 

 as radium or thorium, their atoms continually change, forming en- 

 tirely new elements. As the same atom in some cases breaks down 

 into many different atoms, the original must have been complex. 



Before proceeding with the next step in the establishment of the 

 theory, a brief summary will be of value. The scientist on investiga- 

 tion finds the elements definitely related. The relations are too 

 numerous and too extended to be explained by chance. The scientist 

 can only hope to explain them, if the atom is complex. He finds par- 

 ticles existing much smaller than atoms. From the fact that atoms 

 continually emit them and in emitting them continually change into 

 atoms of different kinds, the scientist believes the atom complex and 

 constituted of these smaller particles called ions or corpuscles. In 

 his procedure thus far, the scientist has assumed nothing. He has in- 

 vestigated the things about which he wished information ; he has foand 

 the atom to be complex and of what it is constituted by examining it 

 by every possible means known to him. Although these atoms and 

 corpuscles manifest themselves to none of his senses; yet he controls 

 them by forces familiar to him and leads them to produce familiar 

 effects, from which he can infer their nature with a certainty which 

 no one understanding his procedure will question. 



[9] 



