1908] 



on 



Carriers of Positive Electricity. 



197 



The questions now arise, can we get any experimental evidence 

 of the existence of these doublets, and is it possible that such systems, 

 if they existed, could have escaped the careful scrutiny which has 

 been given ? The second question is more easily answered than the 

 first, for these doublets being uncharged would not possess the 

 properties which make the positive rays or the cathode rays so 

 noticeable ; thus they would not be deflected by uniform magnetic 

 or electric fields, and the absence of the charge might involve also a 

 loss of the power of producing luminosity when they pass through 

 a gas, and thus render them invisible. With regard to the first 

 question I have made some preliminary experiments, the results of 

 which suggest the existence in the neighbourhood of cathode of 

 neutral systems, such as the doublets which dissociate into corpuscles 

 and positive ions. The arrangement used in these experiments is 

 represented in Fig. 8. 



y 



\ 



Fig. 8. 



The idea of the experiment was as follows. If the secondary 

 cathode rays are produced from the primary without the intervention 

 of the neutral doublet stage, then, as the secondary ionization is due 

 to the secondary cathode rays, a strong electric field, arranged so as 

 to stop the negative corpuscles forming the secondary cathode rays, 

 ought to act as a complete screen against this ionization. If, on the 

 other hand, there is an intermediate stage between the primary and 

 secondary rays, and if this stage consists of neutral doublets, then 

 some of these ought to be able to get through the strong electric 

 field, if this is quite close to the primary rays, because it is only 

 those secondary rays which are produced from the doublets whilst 

 the latter are passing through the field which would be stopped ; the 

 doublets themselves will not be stopped, and if they last long enough 

 to get through the field tliey ought to give rise to ionization on the 

 other side. To test this view the apparatus represented in Fig. 8 

 was used. A copious supply of slowly moving primary cathode rays 



