KELVIN 199 



and the atoms of lead and other permeable substances be 

 absolutely zero or small enough to allow the known per- 

 meation. Taking next the a radiation, the apparent great 

 absorption of the vitreous electric emanation from radium 

 was only apparent. It meant that an atom shot from 

 radium with less than its neutralizing quantum of electrons 

 could not go far through a solid or liquid without acquiring 

 the neutralizing quantum. The ft absorption might be 

 regarded as probably real. Atoms of resinous electricity 

 shot from radium could not be expected to enter a screen 

 of metal, glass, or wood, or liquid, and leave at the other 

 side, irrespectively of the insulation of the screen and 

 of the radium. The full consideration and experimental 

 investigation of the emission of atoms of resinous electricity 

 from radium hermetically sealed in a glass bulb or tube 

 led to surprising and interesting results. As to the 7 rays, 

 there was no difficulty in supposing that non- electrified 

 vapour of radium passed very freely through metals or 

 glass without any electric disturbance. It had been 

 published that loss of weight in the course of a few 

 months had been proved. Keturning to Becquerel's 

 original discovery in respect to uranium the electric con- 

 ductivity induced in air and other gases by a radio-active 

 substance there was a ready explanation in the resuscita- 

 tion of the old doctrine of JEpinus. The ordinary thermal 

 motions within any solid, liquid, or gas must cause 

 occasional shootings out of electrons from the substance, 



