SOME PHYSICAL PROBLEMS 



than we know about such fluids as air or water." 3 

 The results of his studies lead him, he declares, "to a 

 view of electrification which has a striking resemblance 

 to that of Franklin's One Fluid Theory of Electricity. 

 Instead of taking, as Franklin did, the electric fluid to 

 be positive electricity," he says, " we take it to be neg- 

 ative. The 'electric fluid' of Franklin corresponds to 

 an assemblage of corpuscles, negative electrification 

 being a collection of these corpuscles. The transference 

 of electrification from one place to another is effected 

 by the motion of corpuscles from the place where 

 there is a gain of positive electrification to the place 

 where there is a gain of negative. A positively electri- 

 fied body is one that has lost some of its corpuscles." 4 

 According to this view, then, electricity is not a form 

 of energy but a form of matter ; or, to be more precise, 

 the electrical corpuscle is the fundamental structure 

 out of which the atom of matter is built. This is a 

 quite different view from that scarcely less recent one 

 which regards electricity as the manifestation of ether 

 strain, but it must be admitted that the corpuscular 

 theory is supported by a marvellous array of experi- 

 mental, evidence, though it can perhaps hardly be 

 claimed that this brings the theory to the plane of 

 demonstration. But all roads of physical science of late 

 years have seemed to lead towards the electron, as 

 will be made further manifest when we consider the 

 phenomena of radio-activity, to which we now turn. 



RADIO-ACTIVITY 



In 1896, something like a year after the discovery of 

 the X-ray, Niewenglowski reported to the French 



VOL. v. 7 gj 



