ATOMIC DISINTEGRATION. 169 



the radio-active elements. It must also explain radio-activ- 

 ity in general. Any failing in this respect would be fatal to 

 its acceptance. It was stated, page 152 ; that an atom of one 

 of the radio-active elements should consist not only of cor- 

 puscles but of systems of corpuscles. This finds its expla- 

 nation in the systems of rings into which we have shown the 

 corpuscles would necessarily arrange themselves. In addi- 

 tion to this, however, Professor Thomson has proved that 

 these rings of corpuscles need not be concentric. A tri- 

 angular ring of three corpuscles, for example, may exist 

 anywhere in the atomic sphere surrounded by positive elec- 

 tricity, and yet retain its integrity and act like one corpus- 

 cle. We see that the evident complexity of an atom of 

 radium need not worry the theory, for the vast number of cor- 

 puscles it would contain, about 225,000 on the basis of its 

 atomic weight, would of course be exceedingly complex. 

 The explanation of transmutation and radio-activity, how- 

 ever, lies in the energy of the corpuscles, and in the fact 

 that the configurations adopted by the corpuscles depend in 

 certain cases on the energy they contain. This is shown in 

 the arrangements adopted by the little magnets, Fig. 44, 

 where we find that five corpuscles may arrange themselves 

 either in a pentagon or in a square with one corpuscle in 

 the centre. Professor Thomson has demonstrated mathe- 

 matically that a group of four corpuscles, for example, rotat- 

 ing with an angular velocity greater than a certain critical 

 value will arrange themselves at the corners of a square, but 

 that if the velocity falls below this value they will suddenly 

 arrange themselves this time at the corners of a tetrahe- 

 dron. Let us suppose now that we have an atom contain- 

 ing a system of corpuscles of this kind. Suppose that the 

 corpuscles are rotating with an angular velocity far beyond 

 the critical velocity. The configuration is stable enough. 



