330 POPULAR SCIENCE MONTHLY. 



tion of matter have often been advocated; thus in one form of it, 

 known as Front's hypothesis, all the elements were supposed to be 

 compounds of hydrogen. We know, however, that the mass of the 

 primordial atom must be much less than that of hydrogen. Sir'jSTpr- 

 man Lockyer has advocated the composite view of the nature of the 

 elements on spectroscopic grounds, but the view has never been more 

 boldly stated than it was long ago by Xewton who says : 



"The smallest particles of matter may cohere hy the strongest attraction 

 and compose bigger particles of weaker virtue and many of these may cohere 

 and compose bigger particles whose virtue is still weaker and so on for divers 

 succession, until the progression ends in the biggest particles on which the 

 operations in Chemistry and the colours of natural bodies depend and which by 

 adhering compose bodies of a sensible magnitude." 



The reasoning we used to prove that the resistance to the motion 

 of the corpuscle depends only upon the density is only valid when 

 the sphere of action of one of the particles on a corpuscle does not 

 extend as far as the nearest particle. We shall show later on that the 

 sphere of action of a particle on a corpuscle depends upon the velocity 

 of the corpuscle, the smaller the velocity the greater being the sphere 

 of action and that if the velocity of the corpuscle falls as low as 10'^ 

 centimeters per second, then, from what we know of the charge on 

 the corpuscle and the size of molecules, the sphere of action of the 

 particle might be expected to extend further than the distance between 

 two particles and thus for corpuscles moving with this and smaller 

 velocities we should not expect the density law to hold. 



Existence of Free Corpuscles or Negative Electricity in Metals. 



In the cases hitherto described the negatively electrified corpuscles 

 had been obtained by processes which require the bodies from which 

 the corpuscles are liberated to be subjected to somewhat exceptional 

 treatment. Thus in the case of the cathode rays the corpuscles were 

 obtained by means of intense electric fields, in the case of the incan- 

 descent wire by great heat, in the case of the cold metal surface by 

 exposing this surface to light. The question arises whether there is 

 not to some extent, even in matter in the ordinary state and free from 

 the action of such agencies, a spontaneous liberation of those cor- 

 puscles — a kind of dissociation of the neutral molecules of the sub- 

 stance into positively and negatively electrified parts, of which the 

 latter are the negatively electrified corpuscles. 



Let us consider the consequences of some such effect occurring in 

 a metal, the atoms of the metal splitting \ip into negatively electrified 

 corpuscles and positively electrified atoms and' these again after a time 

 re-combining to form neutral system. When things have got into a 

 steady state the number of corpuscles re-combining in a given time 

 will be equal to the number liberated in the same time. There will 



