Rays of Positive Electricity. 431 



the cathode are indicated by a bright yellowish glow. The 

 alteration of the distribution of the Oanalstrahlen as the 

 pressure changes can be followed with great ease by this 

 method. 



To trace the distribution of Oanalstrahlen at a distance 

 from the cathode, I took an insulated aluminium ring (fig. 4) 



Fiff. 4. 



,-=2. 



mounted on a piece of glass tubing, to which a piece of iron 

 was attached, so that by means of a magnet the ring could 

 be moved up or down the tube and its distance from the 

 cathode varied. The ring was first made sensitive to Oanal- 

 strahlen : this was done by moving it up against the cathode 

 ■which had a short glass tube fixed in the middle. A vigorous 

 discharge was then sent from the cathode, and one side of the 

 ring got coated with the sensitive deposit. The ring was 

 then withdrawn from the cathode and moved up and down 

 the tube ; the yellowish glow due to the impact of the ( Oanal- 

 strahlen on the face of the ring turned away from the cathode 

 could be detected at a distance of more than a centimetre 

 and a half from the cathode, showing that even at this 

 distance from the cathode the Oanalstrahlen had sufficient 

 energy to produce their characteristic effect^. 



These and the other effects already described all point to 

 the conclusion that the great speed of the Oanalstrahlen is 

 not due to the direct attraction of the cathode on their 

 positive charges. And since we can get some positively 

 charged particles with energy re] (resented by 20,000 volts 

 when the potential-difference between the electrodes is only 

 3000 volts, it is evident that if the energy of the ( 'analstrahlen 

 is derived from the cathode rays, then the energy of several 

 of the cathode rays must have been drawn upon for the 

 production of one particle in the ( 'analstrahlen, tor the 

 energy of each cathode-ray particle cannot exceed that due 

 to the fall of potential between the terminals of the discharge- 

 tube. Thus, unless we suppose that there is some chemical 

 change in the molecules from which the ( 'analstrahlen arise, 

 resulting in the liberation of energy, we must regard these 

 molecules as capable of storing up the energy communicated 

 to it by cathode particles when they strike against it, so that 



