June 26, 1903.] 



SCIENCE. 



997 



Gauss, Zollner, Hertz, Helmholtz John- 

 stone Stoney, Sir Oliver Lodge, have all 

 contributed to develop the idea— origin- 

 ally due to Weber— which took concrete 

 form when Stoney showed that Faraday's 

 law of electrolysis involved the existence 

 of a definite charge of electricity associated 

 with the ions of matter. This definite 

 charge he called an electron. It was not 

 till some time after the name had been 

 given that electrons were found to be ca- 

 pable of existing separately. 



In 1891, in my inaugural address as 

 president of the Institution of Electrical 

 Engineers,* I showed that the stream of 

 cathode rays near the negative pole was 

 always negatively electrified, the other con- 

 tents of the tube being positively electri- 

 fied, and I explained that 'the division of 

 the molecule into groups of electro-positive 

 and electro-negative atoms is necessary for 

 a consistent explanation of the genesis of 

 the elements. ' In a vacuum tube the nega- 

 tive pole is the entrance and the positive 

 pole the exit for electrons. Falling on a 

 phosphorescent body, yttria, for instance, 

 — a collection of Hertz molecular reson- 

 ators — the electrons excite vibrations of, 

 say, 550 billion times a second, producing 

 ether waves of the approximate length of 

 5.75 ten-millionths of a millimeter, and 

 occasioning in the eye the sensation of 

 citron-colored light. If, however, the elec- 

 trons dash against a heavy metal or other 

 body which will not phosphoresce, they 

 produce ether waves of a far higher fre- 

 quency than light, and are not continuous 

 vibrations, but, according to Sir George 



" Every monad atom has associated with it a 

 certain definite quantity of electricity; every 

 dyad has twice this quantity associated with it; 

 every triad three times as much, and so on." O. 

 Lodge, ' On Electrolysis,' British Association Re- 

 port, 1885. 



* ' Electricity in Transitu : from Plenum to 

 Vacuum,' Journ. Inst Electrical Engineers, Vol. 

 XX., p. 10, January 15, 1891. 



Stokes, simple shocks or solitary impulses; 

 more like discordant shouts as compared 

 with musical notes. 



During that address an experiment was 

 shown which went far to prove the dissocia- 

 tion of silver into electrons and positive 

 atoms.* A silver pole was used, and near 

 it in front was a sheet of mica with a hole 

 in its center. The vacuum was very high, 

 and when the poles were connected with the 

 coil, the silver being negative, electrons 

 shot from it in all directions, and passing 

 through the hole in the mica screen, formed 

 a bright phosphorescent patch on the oppo- 

 site side of the bulb. The action of the coil 

 was continued for some hours, to volatilize 

 a certain portion of the silver. Silver was 

 seen to be deposited on the mica screen 

 only in the immediate neighborhood of the 

 pole; the far end of the bulb, which had 

 been glowing for hours from the impact 

 of electrons, being free from silver deposit. 

 -Here, then, are two simultaneous actions. 

 Electrons, or radiant matter shot from the 

 negative pole, caused the glass against 

 which they struck to glow with phosphores- 

 cent light. Simultaneously, the heavy 

 positive ions of silver, freed from negative 

 electrons, and under the influence of the 

 electrical stress, likewise flew off and were 

 deposited in the metallic state near the 

 pole. The ions of metal thus deposited in 

 all cases showed positive electrification, f 



In the years 1893-1895 a sudden impulse 

 was given to electric vacuum work by the 

 publication in German of the remarkable 

 results obtained by Lenard and Rontgen, 

 who showed that the phenomena inside the 

 vacuum tube were surpassed in interest by 

 what took place outside. It is not too 

 much to say that from this date what had 

 been a scientiflc conjecture became a sober 

 reality. 



* In describing the experiment, one of funda- 

 mental importance, modern terms are employed, 

 t Proc. Roy. Soc, Vol. LXIX., p. 421. 



