368 Dr. E. Goldstein on the Electric 



trode ought evidently to remain free from the platinum deposit. 

 If, however, we examine the glass wall, we find that the sur- 

 face from which the kathode-rays are deflected — as determined 

 at high pressures by the visibility of the blue rays themselves, 

 and at low pressures by means of the phosphorescence which 

 they excite — is just as thickly covered with the platinum as the 

 surrounding portion of the icall, and exactly as we observe to 

 be the case in cylinders where the platinum wire alone acts 

 as kathode while b is not excited. It follows that the rays of 

 the kathode-light are deflected, but not the projected particles 

 of the electrode ; the two cannot therefore be essentially con- 

 nected. 



The discharge is therefore not to be explained by a projec- 

 tion of material particles, either of the substance of the elec- 

 trodes or of the gas. It follows from the experiments on the 

 order of magnitude of the velocity of propagation of electricity, 

 taken together with the views held on the constitution of gases, 

 that the assumption of oscillations of these particles does not 

 afford a satisfactory explanation, and the assumption of motions 

 of rotation remains equally unfruitful. The wall of the con- 

 taining vessel is not altogether neutral in the passage of elec- 

 tricity through the space enclosed by it ; it shows itself 

 phenomena of charge and discharge which appear to be not 

 altogether without influence upon the main discharge between 

 the metallic electrodes. If we wish to go so far as to ascribe 

 to particles possibly torn off from the walls of the vessel when 

 they are discharged the same function which, in the view just 

 considered, gas-particles or electrode-particles were unable to 

 perform, this assumption, quite apart from all new objections, 

 is open to all the objections urged against the previous hypo- 

 thesis. 



Recent investigations have shown that the dust suspended 

 in gases plays an important and previously unsuspected part 

 in the loss of electricity suffered by feebly-charged conductors 

 in the open air, or in gases not specially purified. In almost 

 all cases in which we have hitherto regarded a mass of gas as 

 a carrier of statical electricity, we must now regard the dust 

 suspended in the gas, in cases where drops of liquid cannot be 

 present, as the only vehicle of the electricity. We might 

 easily imagine an hypothesis ascribing a similar essential func- 

 tion to the dust in gases in the case of current electricity as 

 in the case of statical electricity, but that the objections we 

 have previously considered might easily be employed to refute 

 an assumption of the kind. 



The discharge cannot then in general be explained by the 

 motions of ponderable particles ; it follows therefore directly 



