Natures of various Electric Radiations. 14& 



Let ns therefore for the moment suppose the X rays to 

 consist mainly of a stream of neutral pairs. 



We have at once an explanation of the absence of deflexion 

 in electric and magnetic fields, and of regular reflexion and 

 refraction. There should be great penetration, whose amount 

 might vary with the moments of the pairs, or the velocity, if 

 the latter were a variable. We can understand that a pair 

 which struck a light and yielding atom might be returned 

 unchanged : yet if it struck a heavier and more resisting 

 atom it might be disarranged so as to acquire a greater 

 moment, and thus to become a better ionizer, but more readily 

 absorbed. Or it might be shattered altogether, giving rise 

 to a secondary ray of the cathode type. The softer the ray, 

 i. e. the greater the moment of the pair, the more readily 

 might this be done, and the lighter the atom that would do 

 it. (See J. J. Thomson on Barkla's researches, ' Electrician/ 

 April 5, 1907.) 



In order to explain these known effects on the sether-pulse 

 theory it is necessary to suppose that in light atoms the 

 corpuscles are not appreciably acted on by forces due to 

 other corpuscles, but that in heavy atoms there is a strong 

 influence of this kind. In the former case, the thickness of 

 the secondary pulse is the same as that of the primary : in 

 the latter it is not. It is also necessary to suppose that when 

 the atom is heavy enough to cause a modification of the 

 primary radiation, it differs from a light atom in such a way 

 that the pulse can cause cathode particles to be ejected at 

 a speed due to thousands of volts : whereas this is impossible 

 with light atoms. 



If the cathode particles in the X-ray tube so affect the 

 motion of an atom which they strike as to make it throw off 

 a pair, then the plane of rotation of the pair will be the same 

 as that of the atom from which it has come, and will contain 

 the direction of the translatory motion of the pair. The pair 

 will therefore be able to show polarization effects. And if 

 such a pair falls upon a reflecting surface, it is not unreason- 

 able to suppose that it is liable to be taken up only by an 

 atom revolving in the same plane, and sometimes to be 

 ejected again. Thus its subsequent rotation and translation 

 will continue to take place in the one plane. The tertiary ray 

 will therefore be strongest when it is in the same plane as the 

 primary and secondary ; and this is Barkla's polarization effect. 



If the X ray is an aether pulse, it is difficult to understand 

 why the spreading pulse affects so few of the atoms passed 

 over (' Conduction of Electricity through Gases,' pp. 291- 

 297), why the high-speed secondary cathode rays are ejected 



