﻿714 
  ,Prof. 
  G. 
  N. 
  Lewis 
  : 
  A 
  Revision 
  of 
  the 
  

  

  of 
  m/m 
  as 
  a 
  function 
  of 
  /3, 
  namely, 
  

  

  , 
  . 
  m 
  3 
  1 
  /1 
  + 
  /3 
  2 
  , 
  1+/3 
  ,\ 
  

  

  (a) 
  ^ 
  = 
  iM^" 
  log 
  T^- 
  1 
  > 
  

  

  (b) 
  

  

  (c) 
  

  

  m_ 
  i_ 
  

  

  m 
  -(l-y3 
  2 
  )^- 
  

  

  The 
  extraordinary 
  significance 
  o£ 
  the 
  similarity 
  of 
  the 
  first 
  

   two 
  of 
  these 
  equations 
  and 
  the 
  identity 
  of 
  the 
  third 
  with 
  

   equation 
  (15) 
  , 
  which 
  we 
  have 
  derived 
  from 
  strikingly 
  different 
  

   principles, 
  needs 
  no 
  emphasis. 
  Kaufmann 
  shows 
  that 
  his 
  

   results 
  agree 
  better 
  with 
  the 
  first 
  two 
  of 
  these 
  equations 
  than 
  

   with 
  the 
  third, 
  but 
  to 
  regard 
  this 
  as 
  serious 
  evidence 
  as 
  to 
  the 
  

   validity 
  of 
  equation 
  (15) 
  would, 
  as 
  Planck 
  has 
  pointed 
  out, 
  

   be 
  laying 
  too 
  great 
  a 
  stress 
  on 
  the 
  accuracy 
  of 
  the 
  experi- 
  

   mental 
  observations. 
  

  

  The 
  agreement 
  of 
  Kaufmann's 
  results 
  with 
  the 
  above 
  

   equations 
  has 
  led 
  him, 
  and 
  all 
  others 
  who 
  have 
  discussed 
  his 
  

   results, 
  to 
  the 
  conclusion 
  that 
  all 
  of 
  the 
  mass 
  of 
  an 
  electron 
  

   is 
  electromagnetic. 
  

  

  Their 
  argument 
  is 
  based 
  on 
  the 
  assumption 
  that 
  ordinary 
  

   mass, 
  the 
  mass 
  of 
  " 
  ponderable 
  matter," 
  is 
  independent 
  of 
  the 
  

   velocity, 
  while 
  " 
  electromagnetic 
  mass 
  " 
  varies 
  with 
  the 
  

   velocity 
  according 
  to 
  one 
  of 
  the 
  above 
  equations. 
  But 
  in 
  

   this 
  paper 
  we 
  have 
  assumed 
  that 
  all 
  mass 
  is 
  one, 
  and 
  that 
  any 
  

   bodies, 
  whether 
  charged 
  or 
  not, 
  moving 
  at 
  the 
  velocities 
  of 
  

   Kaufmann's 
  electrons 
  would 
  show 
  the 
  same 
  values 
  of 
  m/m 
  . 
  

  

  There 
  is 
  some 
  hope 
  that 
  the 
  correctness 
  of 
  this 
  view 
  may 
  

   be 
  decided 
  by 
  an 
  experimental 
  study 
  of 
  the 
  mass 
  of 
  a 
  positive 
  

   or 
  a 
  particle 
  at 
  different 
  speeds. 
  According 
  to 
  the 
  ordinary 
  

   view, 
  the 
  mass 
  of 
  such 
  a 
  positive 
  particle 
  as 
  issues 
  from 
  a 
  

   radioactive 
  source 
  is 
  chiefly 
  that 
  of 
  its 
  " 
  ponderable 
  " 
  matter 
  

   and 
  only 
  to 
  a 
  very 
  small 
  extent 
  " 
  electromagnetic 
  mass." 
  

   It 
  would 
  therefore 
  be 
  generally 
  assumed 
  that 
  at 
  the 
  highest 
  

   velocity 
  of 
  the 
  particle, 
  about 
  one-tenth 
  of 
  the 
  velocity 
  of 
  

   light, 
  it 
  would 
  have 
  substantially 
  the 
  same 
  mass 
  as 
  at 
  rest. 
  

   According 
  to 
  our 
  view, 
  on 
  the 
  other 
  hand, 
  the 
  mass 
  of 
  this 
  

   or 
  any 
  other 
  particle 
  would 
  change 
  with 
  the 
  velocity 
  in 
  the 
  

   same 
  way 
  as 
  the 
  mass 
  of 
  an 
  electron. 
  From 
  equation 
  (15) 
  

   we 
  should 
  therefore 
  expect 
  the 
  particle 
  moving 
  with 
  one- 
  

   tenth 
  of 
  the 
  velocity 
  of 
  light 
  to 
  have 
  a 
  mass 
  two 
  per 
  cent, 
  

   greater 
  than 
  when 
  at 
  rest. 
  The 
  experimental 
  difficulties 
  in 
  

  

  