/
obtained by Kaufmann, referred to the most penetrating rays of radium. I give for comparison the values obtained by Simon for the cathode rays.
| e/m in electromagnetic units. | v cm/sec |
|---|---|
| 1.865 x 107 | 0.7 x 1010 (For the cathode rays. Simon.) |
| 1.31 x 107 | 2.36 x 1010} |
| 1.17 x 107 | 2.48 x 1010} |
| 0.97 x 107 | 2.59 x 1010} (For the radium rays. Kaufmann.) |
| 0.77 x 107 | 2.72 x 1010} |
| 0.63 x 107 | 2.83 x 1010} |
It is seen that certain β-rays have a velocity approaching that of light. One can understand why it is that particles having such velocity should be able to penetrate matter to such an extent, although they are so small.
The ratio
/
, seems to be the same for the least penetrating radium rays and the cathode rays. But this ratio diminishes as the velocity of the rays increases. J. J. Thomson and Townsend think that all charged electrons, when in motion, possess the same charge, which is equal to that carried by an atom of hydrogen when a solution is electrolyzed. If that be true, it must be admitted that the mass of the particles increases with their velocity, when the latter approaches that of light.