282 ANNUAL EEPORT SMITHSONIAN INSTITUTION, 1910. 



The application of this theory to experimental results has shown 

 that emission and absorption in the spectra of gases and vapors are' 

 caused hy corpuscles identical with the cathode corpuscles,' in otJier 

 words, hy negative electrons. 



Since the discovery of Zeeman nnmerons experimental and theo- 

 retical researches have been carried out with regard to this phe- 

 nomenon which have thrown a new light on the mechanism of emis- 

 sion and absorption. The action of magnetism on the absorption of 

 light has been observed in our laboratory with solid bodies, crystals, 

 and minerals, and experiments have been made at temperatures as low 

 as the solidification of hydrogen (^259°). We shall touch further 

 on upon the novel and unexpected results which attended these re- 

 searches. 



From the foregoing observation, therefore, we find the electron at 

 the very source of all phenomena of light. According to modern 

 theories the transmission of heat and electricity in metals and also the 

 sound and color of metals are explained by the movements of elec- 

 trons circulating freely among the molecules. These numerous facts, 

 of which I have given you a resume, establish the idea that the nega- 

 tive electron which appears in a way tangibly in the /3 rays is a uni- 

 versal constituent of matter. 



We must now take up a vital question : What is the nature of the 

 electrified corpuscle? Is it composed of matter or is it made up of 

 some other essence? Present-clay physics seems to have partially 

 solved this problem. 



Let us consider an electrified body : In the first place such a body 

 possesses a material mass, in the mechanical sense of the word mass ; 

 that is, the ratio of the force acting on the body to the acceleration 

 which it gives that body ; secondly, by reason of the fact that the body 

 is electrified, it possesses another mass of electromagnetic origin; as 

 a matter of fact, if it is in movement, it constitutes an element of the 

 current which is flowing. 



Now, then, every modification in the intensity and direction of the 

 current — that is to say, in the value or direction of the velocity — 

 brings energy into play and gives rise to an effect of induction in 

 the ether. This induction, which opposes every change in direction 

 or intensity (Lenz's law), is a true inertia of electric origin. It is 

 therefore evident that the electrified body has two masses, its mate- 

 rial mass and the electromagnetic mass of the charge which it 

 carries. 



Now, it has been demonstrated that electromagnetic inertia should 

 depend on velocity; that it should remain practically constant if the 

 velocity does not reach a considerable figure (less than 100,000 kilo- 

 meters per second), but that it should increase and approach infinity 



