On the Electric Discharge in Gases. 85 



show the exact position in the spectrum of each of the luminous 

 wires. 



I trust that the ease and rapidity with which the adjust- 

 ments in this apparatus can be made will cause it to be found 

 useful in those many cases in which it is impossible or incon- 

 venient to make use of the more powerful effect of direct 

 sunlight. 



X. On the Electric Discharge in Gases. 

 By Eilhakd Wiedemann. 



[Concluded from p. 54.] 



6. C\N the Nature of the Kathode-rays. — I showed, in my first 

 paper on the Electric Discharge, that the kathode-rays 

 cannot take any important part in the formation of the current 

 and in the transport of the electricity. The strength of the 

 current in a circuit in which a discharge-tube is included 

 remained sensibly the same, whether the kathode-rays were 

 allowed to radiate freely, or whether they were received upon 

 a mica-screen. Recent experiments carried out by other 

 methods by Hertz * lead to exactly the same result. 



What conception, then, are we to form of the kathode-rays? 



In the memoir referred to above, I have endeavoured to 

 show that the view held by Crookes, Puluj, and others, 

 according to which the kathode-rays consist of particles 

 separated from the electrode and projected from it, cannot 

 be sustained. Other reasons are given by Hertz and Gold- 

 steinf. Notwithstanding Herr Puluj, in later publications, 

 without making any experiment to set aside our objections, 

 and sometimes without even referring to them, insists upon 

 his old views. The carrying of particles of the electrode 

 along the kathode-rays is a secondary phenomenon, w r hich 

 has just as little to do with propagation of the motion which 

 corresponds to it as the flight of a cannon-ball has to do with 

 the radiation of the sound produced by the explosion. I 



* Wied. Ann. xix. p. 782 (1883). 



t Wied. Ann. xii. p. 263 (1881). In a reference in the Fortschritte 

 der Physik, 1880, to my paper published in Wied. Ann. x. p. 802, Herr 

 Goldstein asserts that I had incorrectly deduced arguments against motion 

 in the kathode-rays from the experiments of Wheatstone and Von Zahr, 

 and makes objection to them. But an attentive reading of the passage 

 shoe's that I am considering only motion in the ordinary current, as 

 is seen for example from the remark on p. 246 : — " These considerations, 

 which I had already used, Wied. Ann. ix. p. 160, to show that the trans- 

 port of particles takes place in the direction of the current, Herr Goldstein 

 has also repeatedly made use of in describing the processes which take 

 place at the negative electrode." 



