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  LXXVI. 
  The 
  Kinetic 
  Energy 
  of 
  the 
  Ions 
  emitted 
  by 
  Hot 
  

   Bodies. 
  By 
  0. 
  W. 
  RlCHABDSON 
  *. 
  

  

  § 
  1. 
  |X 
  a 
  recent 
  paper 
  the 
  Author 
  and 
  Dr. 
  F. 
  C. 
  Brown 
  t 
  

   X 
  have 
  shown 
  how 
  the 
  magnitude 
  and 
  mode 
  of 
  distri- 
  

   bution 
  of 
  that 
  portion 
  of 
  the 
  translational 
  kinetic 
  energy 
  of 
  

   the 
  ions 
  emitted 
  by 
  hot 
  bodies, 
  which 
  depends 
  on 
  their 
  

   velocity 
  com] 
  onenl 
  perpendicular 
  to 
  the 
  surface 
  at 
  which 
  

   they 
  originate, 
  may 
  be 
  measured. 
  This 
  was 
  done 
  by 
  observ- 
  

   ing 
  the 
  way 
  in 
  which 
  an 
  insulated 
  plate 
  charged 
  up, 
  when 
  it 
  

   was 
  placed 
  at 
  a 
  Bhort 
  distance 
  from 
  a 
  similar 
  and 
  parallel 
  

   plate, 
  a 
  portion 
  of 
  the 
  surface 
  of 
  which 
  consisted 
  of 
  the 
  hot 
  

   metal. 
  The 
  two 
  plate- 
  were 
  initially 
  at 
  the 
  same 
  potential. 
  

   The 
  results 
  of 
  the 
  experiments 
  showed 
  that 
  the 
  mean 
  value 
  

   of 
  this 
  portion 
  of 
  the 
  kinetic 
  energy 
  was 
  the 
  same 
  as 
  the 
  

   corres] 
  onding 
  quantity 
  i'er 
  a 
  molecule 
  of 
  gas 
  at 
  the 
  tempera- 
  

   ture 
  of 
  the 
  hot 
  metal, 
  and 
  thai 
  the 
  velocity 
  component 
  

   perpendicular 
  to 
  the 
  metal 
  surface 
  was 
  distributed 
  among 
  

   the 
  negative 
  ions 
  in 
  accordance 
  with 
  Maxwell's 
  law 
  of 
  the 
  

   distribution 
  of 
  velocity 
  among 
  the 
  molecules 
  of 
  a 
  gas. 
  By 
  

   using 
  the 
  Bame 
  method, 
  I 
  >r. 
  Brown, 
  in 
  an 
  investigation 
  which 
  

   i- 
  n«»t 
  yet 
  published, 
  ha- 
  succeeded 
  in 
  showing 
  that 
  the 
  

   magnitude 
  and 
  mode 
  of 
  distribution 
  of 
  this 
  portion 
  of 
  the 
  

   kinetic 
  energy 
  follow- 
  the 
  Bame 
  law- 
  in 
  the 
  case 
  of 
  the 
  posi- 
  

   tive 
  ion- 
  al-o. 
  

  

  § 
  2. 
  The 
  method 
  employed 
  in 
  those 
  researches 
  yields 
  no 
  

   information 
  about 
  the 
  part 
  of 
  the 
  kinetic 
  energy 
  which 
  

   depends 
  on 
  the 
  component 
  of 
  velocity 
  of 
  the 
  ions 
  parallel 
  to 
  

   the 
  emitting 
  surface. 
  Both 
  the 
  magnitude 
  and 
  distribution 
  

   of 
  this 
  among 
  the 
  ions 
  may. 
  however, 
  he 
  investigated 
  by 
  

   experiments 
  of 
  a 
  somewhat 
  different 
  character. 
  Consider 
  the 
  

  

  Fig. 
  1. 
  

  

  B 
  !A 
  

  

  OH 
  

  

  X 
  Q 
  

  

  arrangement, 
  of 
  which 
  fig. 
  1 
  is 
  a 
  section, 
  to 
  extend 
  indefinitely 
  

   perpendicularly 
  to 
  the 
  plane 
  of 
  the 
  paper. 
  A 
  is 
  a 
  section 
  of 
  an 
  

   infinitely 
  long 
  narrow 
  strip 
  of 
  hot 
  metal 
  which 
  almost 
  fills 
  a 
  

  

  * 
  Communicated 
  bv 
  the 
  Author. 
  

  

  f 
  Phil. 
  Mag. 
  [6] 
  vol. 
  xvi. 
  p. 
  353 
  (1908). 
  

  

  