﻿Energy 
  of 
  Negative 
  Electrons 
  emitted 
  by 
  Hot 
  Bodies. 
  371 
  

  

  potential, 
  and 
  this 
  peculiar 
  state 
  had 
  afterwards 
  been 
  destroyed 
  

   by 
  strongly 
  heating 
  the 
  strip. 
  The 
  last 
  observation 
  but 
  one 
  

   refers 
  to 
  similar 
  conditions, 
  except 
  that 
  the 
  peculiar 
  state 
  

   was 
  induced 
  by 
  charging 
  the 
  upper 
  plate 
  negatively. 
  It 
  is 
  

   possible 
  that 
  some 
  change 
  took 
  place 
  in 
  the 
  strip 
  which 
  made 
  

   the 
  recorded 
  temperatures 
  too 
  high 
  in 
  these 
  two 
  experiments. 
  

   The 
  values 
  of 
  U 
  calculated 
  from 
  the 
  different 
  experiments 
  

   are 
  shown 
  in 
  the 
  last 
  column 
  of 
  the 
  table. 
  These 
  range 
  from 
  

   2-9 
  x 
  10' 
  3 
  to 
  4-2 
  x 
  10 
  3 
  with 
  a 
  mean 
  value 
  of 
  3*5 
  x 
  10 
  3 
  . 
  The 
  

   disagreement 
  of 
  these 
  numbers 
  among 
  each 
  other 
  is 
  probably 
  

   greater 
  than 
  could 
  arise 
  from 
  errors 
  in 
  the 
  measurements 
  of 
  

   any 
  of 
  the 
  physical 
  quantities 
  involved, 
  such 
  as 
  the 
  tempe- 
  

   rature 
  for 
  example. 
  When 
  we 
  consider 
  the 
  number 
  of 
  things 
  

   which 
  appear 
  to 
  affect 
  this 
  phenomenon 
  in 
  a 
  way 
  which 
  is 
  

   not 
  yet 
  understood, 
  the 
  agreement 
  is 
  probably 
  as 
  satisfactory 
  

   as 
  could 
  be 
  expected. 
  The 
  agreement 
  of 
  these 
  numbers 
  with 
  

   the 
  theoretical 
  value 
  R 
  = 
  3'7 
  X 
  10 
  3 
  is 
  very 
  striking, 
  and 
  seems 
  

   scarcely 
  likely 
  to 
  be 
  a 
  chance 
  coincidence. 
  

  

  Date 
  

  

  Jan. 
  29. 
  

   Jan. 
  31. 
  

  

  b. 
  5. 
  

  

  Feb. 
  10. 
  

  

  Mar. 
  8. 
  

   Mar. 
  9. 
  

  

  Mar. 
  13. 
  

  

  Mar. 
  14. 
  

  

  Treatment 
  of 
  Platinum 
  before 
  

   Observations. 
  

  

  1G 
  hours' 
  heating 
  

  

  f 
  Just 
  after 
  lime 
  was 
  placed 
  on 
  

  

  | 
  platinum 
  

  

  f 
  Just 
  after 
  hydrogen 
  was 
  let 
  

  

  \ 
  into 
  vacuum 
  

  

  About, 
  35 
  hours' 
  heating 
  

  

  About 
  30 
  hours' 
  heating 
  

  

  Highly 
  charged 
  with 
  negative 
  

   electricity 
  and 
  strongly 
  

  

  heated 
  subsequently 
  

  

  Highly 
  charged 
  with 
  positive 
  

   electricity 
  and 
  strongly 
  i 
  

   heated 
  subsequently 
  

  

  Pressure, 
  

  

  •015 
  

   •008 
  

   •009 
  

   •006 
  

   •06 
  

  

  •04 
  

  

  •015 
  

   •01 
  

  

  •02 
  

  

  Absolute 
  

   Tempe- 
  

   rature. 
  

  

  1556 
  

   1473 
  

  

  1503 
  

  

  1553 
  

  

  1660 
  

   1560 
  

  

  1840 
  

  

  1813 
  

  

  Maximum 
  

  

  Current, 
  

  

  amperes. 
  

  

  4-7 
  X10" 
  11 
  

   l-2xl0-n 
  

  

  3X10- 
  11 
  

  

  4x10-11 
  

  

  l-4 
  X 
  10-ii 
  

  

  3x10-12 
  

  

  4x10-11 
  

  

  lxio-n 
  

  

  4-lxl0 
  J 
  

   4-2 
  XlO 
  3 
  

  

  3-5 
  X10 
  3 
  

  

  3-6 
  XlO 
  3 
  

  

  2-9 
  XlO 
  3 
  

   3-1X103 
  

  

  3-2x103 
  

   3-4x103 
  

  

  In 
  order 
  to 
  test 
  the 
  theory 
  further 
  the 
  obvious 
  thing 
  to 
  

  

  ve 
  

  

  try 
  was 
  whether 
  the 
  coefficient 
  jtk 
  deduced 
  from 
  the 
  log 
  i, 
  V 
  

  

  diagram 
  really 
  was 
  universally 
  proportional 
  to 
  the 
  absolute 
  

   temperature. 
  A 
  glance 
  at 
  the 
  preceding 
  table 
  will 
  show 
  

   that 
  in 
  the 
  case 
  of 
  platinum 
  this 
  is 
  a 
  difficult 
  if 
  not 
  im- 
  

   possible 
  task. 
  The 
  disagreement 
  between 
  the 
  different 
  deter- 
  

   minations 
  of 
  R 
  shows 
  a 
  greater 
  ratio 
  of 
  variation 
  than 
  the 
  

   fractional 
  change 
  in 
  the 
  absolute 
  temperature 
  over 
  the 
  whole 
  

   range 
  of 
  temperature 
  during 
  which 
  the 
  effect 
  could 
  conve- 
  

   niently 
  be 
  measured. 
  For 
  this 
  reason 
  it 
  seemed 
  likely 
  that 
  

  

  2 
  C2 
  

  

  