378 Dr. E. Goldstein on the Electric 



That the so-called aether-envelopes of the gas-molecnles or 

 atoms take part in the emission of light resulting from the dis- 

 charge is a matter of course ; but the part which they play in 

 the processes of charging and discharging must remain for 

 future discussion. The forces exerted by the material particles 

 upon which the formation of the aether-envelopes depends, tend 

 to produce a different disposition of the aether from that which 

 would result from the electrical forces only. Consequently 

 the more gas-molecules are included in the space occupied 

 by the discharge, the greater the electrical forces must be 

 in order to bring about the disposition of the aether which 

 must precede the discharge. Hence we understand how the 

 gas acts as a hindrance to the discharge, and why conduc- 

 tivity of the space occupied by the discharge continually im- 

 proves as the gas is more and more completely removed. 

 In any case, I am unable to accept E. Wiedemann's view*, 

 according to which the aether-envelopes are the real medium 

 of the discharge. If, moreover, the aether-envelopes suffer 

 deformations without the free aether taking any part in the 

 process (and in the case of the kathode-discharge Wiedemann 

 excludes any such participation), then, as regards the velocity 

 of propagation of the discharge, Wiedemann must assume 

 a pure distance-action between the aether-envelopes, since in 

 highly rarefied gases we regard the times during which the 

 aether-envelope and the sphere of action of a molecule are in 

 contact with those of other molecules, or penetrate them, as 

 small in comparison with the times during which the sphere 

 of activity is isolated. 



The assumption that the direction of the negative current 

 from the kathode is the direction in which the electric dis- 

 charge is propagated in the kathode-light, and also in the 

 secondary negative pencils and positive stratifications, con- 

 trary to the usual view, seems to be justified by numerous 

 experimental results. I would call attention, first of all, to 

 the phenomena of shadows, which, formerly observed only 

 with the kathode-light, have caused this phenomenon to be 

 represented as a motion from the kathode, even by the de- 

 fenders of the convection theory. 



If a solid body be placed in a pencil of the kathode-light, 

 or of the secondary negative light, then, as may be observed 

 directly, that portion of the pencil falling upon the object which 

 lies between its end turned towards the kathode and the object 

 itself remains in every case intact, but that portion of the in- 

 cident pencil lying on the further side of the space occupied 

 by the object is wanting. The shadows previously described f, 



* E. Wiedemann, Wied. Ann. x. p. 245, 1880 ; Phil. Mag. [5] x. p. 419. 

 t Phil. Mag. [5] x. p. 236. 



