CHAPTER XXII 



ELECTRONIC MAGNITUDES 



IN Chapter XIV the conduction of electricity through 

 highly rarefied gases was explained in terms of elec- 

 trons. The phosphorescence of the sides of a glass 

 tube in which such conduction is taking place is due 

 to the impacts of electrons proceeding with high 

 velocities away from the cathode. 1 Before it was 

 proved that this stream was corpuscular it was assumed 

 that it was a new kind of "light," that is, an electro- 

 magnetic radiation, and hence the misnomer "cathode 



rays." For experimental 

 purposes the stream may be 

 made a band (indicated by 

 the dotted line in Fig. 37) 

 by arranging the anode A 

 as a hollow cylinder. A 

 Fi 7 magnetic field at right an- 



gles to this ray was found 



to bend it in the same direction as we would now 

 expect with our knowledge that it is a stream of elec- 

 trons. By deflecting it into the metal vessel V, 

 which was connected to an electroscope, it was found 

 that the ray carried a negative charge. That it is a 

 stream of negative particles was further indicated by 

 the fact that it undergoes a deflection in the proper 



1 Or in some cases to ultra-violet light produced at the cathode. 



304 



