Discharge in Rarefied Gases, 375 



charge by the free aether is commonly supposed to be refuted 

 (where it is mentioned at all as a possible case, e. g. in text- 

 books) by a reference to the experience of spectrum-analysis. 

 If the aether were the vehicle of the discharge, it is said, all 

 gases would give the same spectrum — the spectrum of aether — 

 when subjected to the discharge. But since each gas has a 

 special characteristic spectrum, the gass mass must be regarded 

 as the conductor of the electricity. But it is well known that 

 the aether itself has no power of emitting light. The fact that 

 it has no " spectrum " is therefore no evidence that it cannot 

 conduct electricity. With equal justice it might be argued 

 that the phenomena of light and heat due to a current can 

 only be produced in the molecules of the conducting substance; 

 every conductor in whose mass non-conducting particles are 

 embedded proves the contrary. The luminosity of a gas pro- 

 duced by the discharge depends entirely upon its molecules 

 possessing the form and period of oscillation which are neces- 

 sary for the emission of visible rays. That this vibrating 

 motion is accompanied by motion due to electricity, executed 

 by the particles themselves or their aether-envelopes, does not 

 seem to be necessary; but, as the phenomena of fluorescence 

 and phosphorescence in sunlight show, the molecules of bodies 

 may execute motions of the form and period of the vibrations 

 of light by taking up the vibrations of the surrounding free 

 aether. 



I assume that a similar process take place when a gas is 

 rendered luminous by the electric discharge. The discharge 

 itself represents a motion of the free aether, and is in itself 

 non-luminous. This motion of the aether disappears, being 

 communicated to the gas-molecules and their constituent 

 atoms ; the particles of each molecule then vibrate in accord- 

 ance with their special structure and the conditions as to 

 elasticity of the molecule, and communicate again to the 

 aether the transversal vibrations so produced as such; thus the 

 original motion which the aether possessed as electricity is 

 converted into light, and of course into light whose oscilla- 

 tion-periods depend upon the specific nature of the gas-mole- 

 cules. The difference in spectrum between chemically dif- 

 ferent gases thus in no way disproves the conduction of elec- 

 tricity by the aether. I thus regard the luminosity of gases 

 traversed by the electric current as a phenomenon of reson- 

 ance. I should not be disposed to regard it as a phenomenon 

 of fluorescence or phosphorescence, for two reasons : — (1) 

 Because in fluorescence and phosphorescence the vibrations 

 are transferred from the aether to the atoms, and back again to 

 the aether, without changing their character as transversal 



