1901.] on the Existence of Bodies Smaller than Atoms. 583 



the rate with which the heat is carried will increase with the number 

 of corpuscles and with their mobility, it will be influenced by the same 

 circumstances as the conduction of electricity, so that good conductors 

 of electricity should also be good conductors of heat. If we calculate 

 the ratio of the thermal to the electric conductivity on the assumption 

 that the whole of the heat is carried by the corpuscles, we obtain a 

 value which is of the same order as that found by experiment. 



Weber many years ago suggested that the electrical conductivity 

 of metals was due to the motion through them of positively and nega- 

 tively electrified particles, and this view has recently been greatly 

 extended and developed by Riecke and by Drude. The objection to 

 any electrolytic view of the conduction through metals is that, as in 

 electrolysis, the transport of electricity involves the transport of matter, 

 and no evidence of this has been detected ; this objection does not 

 apply to the theory sketched above, as on this view it is the corpuscles 

 which carry the current ; these are not atoms of the metal, but very 

 much smaller bodies which are the same for all metals. 



It may be asked, if the corpuscles are disseminated through the 

 metal and moving about in it with an average velocity of about 10 7 

 centimetres per second, how is it that some of them do not escape from 

 the metal into the surrounding air ? We must remember, however, that 

 these negatively electrified corpuscles are attracted by the positively 

 electrified atoms and in all probability by the neutral atoms as well, 

 so that to escape from these attractions and get free a corpuscle would 

 have to possess a definite amount of energy : if a corpuscle had less 

 energy than this then, even though projected away from the metal, it 

 would fall back into it after travelling a short distance. When the 

 metal is at a high temperature, as in the case of the incandescent wire, 

 or when it is illuminated by ultra-violet light, some of the corpuscles 

 acquire sufficient energy to escape from the metal and produce elec 

 trification in the surrounding gas. We might expect too that, if we 

 could charge a metal so highly with negative electricity, that the 

 work done by the electric field on the corpuscle in a distance not 

 greater than the sphere of action of the atoms on the corpuscles was 

 greater than the energy required for a corpuscle to escape, then the 

 corpuscles would escape and negative electricity stream from the 

 metal. In this case the discharge could be effected without the 

 participation of the gas surrounding the metal and might even take 

 place in an absolute vacuum, if we could produce such a thing. We 

 have as yet no evidence of this kind of discharge, unless indeed some 

 of the interesting results recently obtained by Earhart with very 

 short sparks should be indications of an en'ect of this kind. 



A very interesting case of the spontaneous emission of corpuscles 

 is that of the radio-active substance radium discovered by M. and 

 Madame Curie. Eadium gives out negatively electrified corpuscles 

 which are deflected by a magnet. Becquerel has determined the ratio 

 of the mass to the charge of the radium corpuscles, aud finds it is the 

 same as for the corpuscles in the cathode rays. The velocity of the 



