98 



offers the more natural explanation of the facts that only a 

 minute fraction of the atoms traversed by a bundle of X-rays 

 are ionized, and that the character of the ionisation is inde- 

 pendent of the intensity of the rays. 



It is clear from Marx's experiment that some ether waves 

 are present in a bundle of X-rays. Their presence will 

 readily account for the diffraction effects of Haga and Wind. 



To sum up a curious and interesting situation, it may be 

 said to be clear that X-rays contain ether pulses, but that a 

 large number of X-ray properties are not easy to explain on 

 the hypothesis that the rays contain ether pulses only. The 

 difficulties disappear on the hypothesis that they contain 

 neutral pairs also : a hypothesis which is by no means im- 

 probable a priori. But the existence of these pairs has not 

 yet been absolutely proved. 



I should like to add one remark in reference to the y ray. 

 If the latter is material and contains an a particle, this fact 

 must be considered in reckoning the number and magnitude 

 of the steps from the atomic weight of radium to that of lead. 

 It has been suggested to me by my colleague Dr. Rennie that 

 the rayless changes of Ra may really be accompanied by the 

 emission of neutral pairs of very small moment. This adds 

 another unknown factor to the calculation. The energy in- 

 volved in such emissions might be quite small, and, moreover, 

 if pairs can be taken up into atoms, so as to form new atoms, 

 the whole of the energy may not appear as heat. 



