1907.] 



Rays of Positive Electricity. 



577 



WEEKLY EVENING MEETING, 

 Friday, March 22, 1907. 



His Grace The Duke of Northumbeeland, K.G. P.C. D.C.L. 

 F.R.S., President, in the Chair. 



Professor J. J. Thomson, M.A. LL.D. D.Sc. F.R.S. M.R.I., 

 Professor of Natural Philosophy R.I. 



Rays of Positive Electricity. 



In 1886 Goldstein discovered that when the cathode in a discharge- 

 tube is perforated, rays pass through the openings and produce 

 luminosity in the gas beliind the cathode ; the colour of the light 

 depends on the gas with which the tube is filled, and coincides with 

 the colour of the velvety glow which occurs immediately in front of 

 the cathode. The appearance of these rays is indicated in Fig. 1, 

 the anode being to the left of the cathode KK. Since 

 the rays appeared through narrow channels in the ^ 



■cathode, Goldstein called them " Kanalstrahlen " ; now ,^ 

 that we know more about their nature, " positive rays " -^ 

 wo aid, I think, be a more appropriate name. Gold- 

 stein showed that a magnetic force which would deflect 

 cathode rays to a very considerable extent was quite 

 without effect on the " Kanalstrahlen." By using 

 intense magnetic fields, W. Wien showed that these 

 rays could be deflected, and that the deflection was in 

 the opposite direction to that of the cathode rays, in- 

 dicating that these rays carry a positive charge of 

 electricity. This was confirmed by measuring the 

 electrical charge received by a vessel into which the 

 rays passed through a small hole, and also by observ- 

 ing the direction in which they are deflected by an /r 

 electric force. By measuring the deflections under Fig. 

 magnetic and electric forces, Wien found by the usual 



Itp^^^^ 



methods the value of and the velocity of the rays. 



He found for 



the maximum value of the value of lO^*, which is the same as that 



m 



for an atom of hydrogen in the electrolysis of solutions. 

 Vol. XVIII. (No. 101) 



A valuable 



2 p 



