﻿146 
  ANNUAL, 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1922. 
  

  

  as 
  a 
  theory 
  but 
  as 
  a 
  fact. 
  But 
  when 
  we 
  attempt 
  to 
  explain 
  all 
  the 
  

   physical 
  and 
  chemical 
  properties 
  of 
  matter 
  as 
  due 
  to 
  these 
  electrons 
  

   and 
  the 
  electromagnetic 
  forces 
  between 
  them 
  we 
  encounter 
  some 
  sur- 
  

   prising 
  and 
  unexpected 
  facts 
  regarding 
  the 
  behavior 
  of 
  electrons 
  

   when 
  influenced 
  by 
  other 
  electrons 
  or 
  by 
  radiation, 
  so 
  that 
  this 
  is 
  

   still 
  a 
  field 
  of 
  hypothesis 
  and 
  experimentation. 
  

  

  NEGATIVE 
  AND 
  POSITIVE 
  ELECTRONS. 
  

  

  Properties 
  of 
  the 
  negative 
  electron. 
  — 
  When 
  an 
  electric 
  discharge 
  

   at 
  several 
  thousand 
  volts 
  is 
  passed 
  between 
  two 
  metallic 
  electrodes 
  

   sealed 
  into 
  a 
  glass 
  vessel 
  from 
  which 
  most 
  of 
  the 
  air 
  or 
  other 
  gas 
  

   has 
  been 
  pumped, 
  the 
  remaining 
  gas 
  and 
  the 
  walls 
  of 
  the 
  glass 
  vessel 
  

   become 
  luminous. 
  This 
  luminosity 
  is 
  of 
  different 
  sorts 
  in 
  different 
  

   parts 
  of 
  the 
  vessel 
  and 
  can 
  easily 
  be 
  shown 
  to 
  be 
  due 
  to 
  two 
  different 
  

   agents. 
  One 
  of 
  these 
  consists 
  of 
  something 
  shooting 
  out 
  from 
  the 
  

   cathode, 
  or 
  negative 
  electrode, 
  and 
  producing 
  luminosity 
  in 
  every- 
  

   thing 
  in 
  its 
  path. 
  The 
  other 
  consists 
  of 
  something 
  shooting 
  out 
  from 
  

   the 
  anode 
  and 
  moving 
  toward 
  the 
  cathode, 
  also 
  producing 
  luminosity 
  

   of 
  gas 
  molecules 
  or 
  other 
  objects 
  in 
  its 
  path, 
  but 
  luminosity 
  of 
  a 
  

   different 
  color 
  from 
  that 
  produced 
  by 
  the 
  stream 
  from 
  the 
  cathode. 
  

  

  The 
  so-called 
  cathode 
  rays 
  are 
  found 
  to 
  consist 
  of 
  a 
  stream 
  of 
  

   negatively 
  charged 
  particles, 
  as 
  is 
  proved 
  by 
  the 
  fact 
  that 
  their 
  

   paths 
  are 
  bent 
  if 
  placed 
  in 
  an 
  electric 
  or 
  magnetic 
  field, 
  or 
  by 
  the 
  

   fact 
  that 
  if 
  they 
  are 
  caught 
  in 
  a 
  metallic 
  cup, 
  this 
  cup 
  receives 
  a 
  

   charge 
  of 
  negative 
  electricity. 
  From 
  the 
  amount 
  of 
  bending 
  in 
  elec- 
  

   tric 
  and 
  magnetic 
  fields 
  of 
  known 
  strength, 
  which 
  may 
  be 
  seen 
  by 
  

   the 
  luminous 
  trace 
  of 
  the 
  path 
  of 
  the 
  stream 
  along 
  a 
  properly 
  placed 
  

   fluorescent 
  plate, 
  it 
  is 
  possible 
  to 
  calculate 
  the 
  speed 
  of 
  the 
  particles 
  

   and 
  the 
  ratio 
  of 
  their 
  charge 
  to 
  their 
  mass, 
  denoted 
  by 
  e/m. 
  The 
  

   speed 
  of 
  the 
  particles 
  depends 
  upon 
  the 
  voltage 
  applied 
  to 
  the 
  dis- 
  

   charge 
  tube, 
  but 
  the 
  value 
  of 
  e/m 
  does 
  not 
  depend 
  on 
  the 
  voltage 
  

   or 
  the 
  kind 
  of 
  gas 
  in 
  the 
  vessel 
  or 
  the 
  material 
  of 
  the 
  electrodes. 
  

   It 
  is 
  a 
  definite 
  constant 
  about 
  1,846 
  times 
  larger 
  than 
  the 
  ratio 
  of 
  

   the 
  charge 
  to 
  the 
  mass 
  of 
  hydrogen 
  ions 
  liberated 
  by 
  electrolysis. 
  

   Thus, 
  if 
  the 
  charge 
  on 
  one 
  of 
  these 
  particles 
  is 
  equal 
  to 
  the 
  charge 
  

   on 
  a 
  hydrogen 
  ion 
  (as 
  we 
  shall 
  see 
  is 
  the 
  case), 
  then 
  these 
  particles 
  

   must 
  be 
  1,846 
  times 
  lighter 
  than 
  hydrogen 
  atoms. 
  These 
  particles, 
  

   which 
  constitute 
  the 
  cathode 
  rays, 
  are 
  the 
  negative 
  electrons. 
  They 
  

   may 
  be 
  driven 
  out 
  of 
  metals 
  by 
  raising 
  the 
  temperature 
  or 
  by 
  ex- 
  

   posing 
  to 
  ultra-violet 
  light 
  or 
  X 
  rays, 
  or 
  by 
  intense 
  bombardment, 
  

   or 
  by 
  chemical 
  actions, 
  etc. 
  Their 
  properties, 
  as 
  regards 
  mass 
  and 
  

   charge, 
  are 
  the 
  same 
  however 
  they 
  are 
  liberated 
  and 
  they 
  must 
  be 
  

   considered 
  as 
  one 
  of 
  the 
  fundamental 
  units 
  of 
  which 
  matter 
  is 
  com- 
  

   posed. 
  

  

  