Hays of Positive Electricity. 767 



the field it was resolved into two with magnetic deflexions 

 6'0 and 53 millimetres ; the square of the ratio of these 

 deflexions is 1*28, the ratio of the atomic weights of and C 

 is 1*33, which agrees with the preceding value within the 

 accuracy of the experiments. The spot a was compared with 

 6, the corresponding magnetic deflexions are : 



b, a. Square of the ratio. 



5-0 1'5 11-1 



50 1'3 13-6 



Mean 12-35 



For mercury vapour the square of the ratio would have 

 been 14 if the spot b were due to nitrogen, 12 if it were due 

 to oxygen. The deflexion of the spot a with the magnetic 

 force available was too small to admit of accurate measure- 

 ment, but there can, I think, be little doubt that the spot a 

 is due to mercury vapour. Jt disappears very quickly when 

 liquid air is put around some charcoal in a side tube. 



Thus w r e see that on the assumption that the charges are 

 equal, we see that all the carriers with the exception of those 

 for spot d are in the atomic condition ; a very remarkable 

 result, and one which has an important bearing on the 

 dissociation of gases in the discharge-tube. It will be inter- 

 esting to liberate the different elements from compounds of 

 different types when they have different valencies, and from 

 carbon compounds where the bands are different, and see 

 whether the value of e/m remains unaltered. 



The absence of the negative part of the phosphorescence 

 indicates a reluctance on the part of the atoms of some gases 

 to acquire a negative charge ; this, is also brought out by 

 Franck's discovery that in some gases from which oxygen 

 has been carefully excluded the velocity of the negative ion 

 was veiy many times greater than when oxygen was admitted, 

 while the positive ion was not affected. This indicates that 



: negative corpuscle does not readily attach itself to the 

 molecules of these gases. 



I had occasion in the course of the work to investigate 

 the secondary Oanalstrahlen produced when primary Canal- 

 strahlen strike against a metal plate. I found that the 

 secondary rays which were emitted in all directions were for 

 the most part uncharged, but that a small fraction carried 

 a positive charge. 



I have much pleasure in thanking Mr. F. W. Aston, of 

 Trinity College, Cambridge, and Mr. E. Everett, for the 

 kind assistance they have given me with these experiments. 



