TROWBRIDGE. — MAGNETIC FIELD AND THE CATHODE RAYS. 401 



the centre of the iron terminal, the other around the periphery of this 

 terminal. 



It was to be expected that the Canalstrahlen could not be brought 

 to convergence by this application of a longitudinal magnetic field. 

 The phosphorescence of these rays remained unaffected. 



Phosphorescence of the Canal Rays. 



In most cases the phosphorescence caused by the Canalstrahlen is 

 similiar in color to that produced by the cathode rays. When, how- 



FlGlRE 2. 



ever, the Canalstrahlen fall upon lithium chloride, there seems to be a 

 marked difference. Professor J. J. Thomson in his treatise on Con- 

 duction of Electricity through Gases ^ describes a form of tube in which 

 a layer of lithium chloride can be bombarded alternately by both kinds 

 of rays, and says that when the layer is struck by the Canalstrahlen it 

 shines with a bright red light ; the lines of the lithium spectrum are 

 very bright, and when the direction of the discharge is reversed, so that 

 the layer is struck by the cathode rays, its color changes from bright red 

 to steely blue, giving only a faint continuous spectrum but not the 

 lithium lines. The layer speedily becomes black in hydrogen. 



2 University Press, Cambridge, 1906, p. 042. 



VOL. XLIII. — 26 



