﻿Energy 
  of 
  the 
  Ions 
  emitted 
  by 
  Hot 
  Bodies. 
  

  

  905 
  

  

  +.r 
  (cms.). 
  

  

  Arbitrary 
  units. 
  

  

  log?. 
  

  

  x 
  2, 
  (cm. 
  2 
  ). 
  

  

  i+. 
  

  

  i 
  — 
  . 
  

  

  i 
  (mean). 
  

  

  •00 
  

  

  5 
  

  

  5 
  

  

  5 
  

  

  •699 
  

  

  

  

  •01 
  

  

  4-47 
  

  

  4-17 
  

  

  432 
  

  

  •635 
  

  

  lxicr 
  4 
  

  

  •02 
  

  

  1-8 
  

  

  2-95 
  

  

  2-38 
  

  

  •376 
  

  

  4xl0~ 
  4 
  

  

  •03 
  

  

  •7 
  

  

  1-8 
  

  

  1-25 
  

  

  •097 
  

  

  9xl0- 
  4 
  

  

  •04 
  

  

  •35 
  

  

  •70 
  

  

  •525 
  

  

  1-720 
  

  

  16X10- 
  4 
  

  

  •05 
  

  

  •15 
  

  

  •30 
  

  

  •225 
  

  

  1-353 
  

  

  25XI0- 
  4 
  

  

  •06 
  

  

  ■05 
  

  

  •13 
  

  

  •09 
  

  

  2-954 
  

  

  36X10 
  -4 
  

  

  On 
  plotting 
  these 
  values 
  of 
  log 
  i 
  against 
  a? 
  they 
  behave 
  

   exactly 
  like 
  those 
  in 
  the 
  preceding 
  table. 
  The 
  first 
  four 
  

   values 
  lie 
  on 
  a 
  straight 
  line 
  from 
  which 
  the 
  others 
  show 
  a 
  

   gradually 
  increasing 
  divergence. 
  On 
  substituting 
  the 
  values 
  

   of 
  x?—x£ 
  and 
  of 
  log 
  10 
  «2 
  — 
  logio 
  h 
  obtained 
  from 
  this 
  line 
  

   and 
  the 
  Values 
  V=78'3xl0 
  8 
  , 
  = 
  1-15 
  x 
  10 
  3 
  , 
  and 
  ^ 
  = 
  '534 
  

   proper 
  to 
  the 
  experiment, 
  together 
  with 
  ne 
  = 
  '814:, 
  we 
  obtain 
  

   R 
  = 
  2*8xl0 
  3 
  . 
  If 
  we 
  had 
  taken 
  ne 
  = 
  '4c07 
  we 
  should 
  have 
  

   found 
  R 
  = 
  l'4xl0 
  3 
  . 
  The 
  results 
  given 
  by 
  this 
  method 
  are 
  

   therefore 
  in 
  general 
  agreement 
  with 
  those 
  obtained 
  by 
  the 
  

   first 
  method 
  for 
  this 
  experiment. 
  

  

  § 
  6. 
  Third 
  Method. 
  

  

  (a) 
  Negative 
  Ions. 
  — 
  The 
  third 
  method, 
  which 
  is 
  inde- 
  

   pendent 
  of 
  the 
  first 
  two, 
  is 
  based 
  upon 
  equation' 
  (6) 
  and 
  

   depends 
  on 
  the 
  measurement 
  of 
  i 
  , 
  the 
  fraction 
  of 
  the 
  total 
  

   number 
  of 
  ions 
  which 
  pass 
  through 
  the 
  slit 
  when 
  in 
  the 
  

   symmetrical 
  position, 
  and 
  f, 
  the 
  width 
  of 
  the 
  slit. 
  Unfor- 
  

   tunately 
  the 
  present 
  apparatus 
  was 
  not 
  constructed 
  so 
  that 
  

   this 
  method 
  could 
  be 
  applied 
  in 
  an 
  accurate 
  way. 
  In 
  

   deducing 
  equation 
  (6) 
  we 
  assumed 
  that 
  the 
  slit 
  extended 
  

   the 
  whole 
  way 
  across 
  the 
  plates 
  and 
  that 
  the 
  electrode 
  

   behind 
  covered 
  the 
  whole 
  of 
  the 
  slit 
  and 
  received 
  all 
  of 
  the 
  

   ions 
  which 
  passed 
  through 
  it. 
  In 
  the 
  experiments 
  this 
  was 
  

   far 
  from 
  being 
  the 
  case 
  ; 
  the 
  length 
  of 
  the 
  electrode 
  behind 
  

   the 
  slit 
  was 
  3*7 
  mms., 
  whilst 
  the 
  breadth 
  of 
  the 
  plates 
  was 
  

   7*7 
  mms. 
  If 
  the 
  hot 
  strip 
  were 
  indefinitely 
  long 
  this 
  would 
  

   easily 
  be 
  corrected 
  by 
  simply 
  multiplying 
  the 
  observed 
  

   values 
  of 
  i 
  by 
  7'7/3*7 
  = 
  2 
  , 
  08. 
  The 
  matter 
  is 
  not 
  so 
  simple 
  

   as 
  this, 
  however, 
  for 
  the 
  length 
  of 
  the 
  hot 
  strip 
  was 
  only 
  

  

  