Light and Electrons. 181 



gases. Also that the same limiting value of energy will be 

 attained by a resonator of definite frequency, when damping 

 by radiation is taken into account ; irrespective apparently 

 of periodicity in the exciting cause. 



These considerations however, though they may well 

 apply to an electron inside an atom, cannot extend to the 

 actual liberation of an electron by X or other radiation ; 

 since in that case the real and dominant influence of the 

 frequency of the incident waves has been established experi- 

 mentally, and it is known that the energy of ejection is 

 proportional to the frequency of the incident radiation. 



But it seems likely enough that the store of accumulated 

 energy, which has brought a corpuscle rather near expulsion 

 without actually expelling it, may have been obtained from 

 the miscellaneous radiation \\ Inch is never absent save at 

 absolute zero ; and that then the surplus energy or added 

 stimulus is supplied from a synchronous ether-disturbance, 

 until first one and then another particle, possessing the 

 right frequency n, shall really be moving with the critical 

 velocity v, and be promptly ejected. A very slight s} r ntonic 

 stimulus might suffice, since energy could still be received 

 from the irregular jostling, even when a regular disturbance 

 was superposed. 



In that way the difficulty of whence the energy comes 

 may be evaded, seeing that the greater part of the accumu- 

 lated energy is independent of the incident light, while yet 

 the actual ejection is effected by that light and is dependent 

 on its frequency. 



We have still to show that a corpuscle would not be 

 ejected without the syntonic disturbance, by reason of 

 random impacts alone. We must therefore reckon the speed 

 which at ordinary temperatures can be reached by means 

 of irregular jostling, taking it as that given by the laws of 

 gases, — the gas having the electronic atomic weight, which 

 is l/1845th that for hydrogen. 



The average gas velocity at the absolute temperature T is 

 given by 



u* = 3RT = 3 5. 



P 



The value of R for hydrogen is 41'ti x 10 6 ergs per centigrade 

 degree, while for oxygen it is 1/16 th as great. So for a gas 

 composed of electrons it is 



R E = 41-6 x 10 6 x 1845 = 7*68 x 10 10 . 



