﻿370 
  Prof. 
  Richardson 
  and 
  Mr. 
  Brown 
  on 
  the 
  Kinetic 
  

  

  conclusions 
  from 
  ; 
  but 
  in 
  the 
  case 
  of 
  the 
  lime-covered 
  strip 
  

  

  more 
  consistency 
  was 
  observed. 
  The 
  main 
  feature 
  of 
  the 
  

  

  change 
  consisted 
  in 
  a 
  reduction 
  of 
  the 
  curvature 
  of 
  the 
  curve 
  

  

  connecting 
  the 
  current 
  and 
  the 
  potential. 
  This 
  reduction 
  

  

  was 
  greater 
  the 
  higher 
  the 
  temperature 
  of 
  the 
  lime-coated 
  

  

  strip, 
  and 
  also 
  therefore 
  the 
  greater 
  the 
  absolute 
  value 
  of 
  the 
  

  

  current. 
  At 
  higher 
  temperatures 
  the 
  current 
  appeared 
  

  

  within 
  the 
  limits 
  of 
  experimental 
  error 
  to 
  be 
  a 
  linear 
  

  

  function 
  of 
  the 
  potential 
  instead 
  of 
  an 
  exponential 
  function, 
  

  

  In 
  one 
  experiment 
  the 
  current 
  was 
  3*4 
  x 
  10 
  -8 
  amp. 
  for 
  ^ 
  = 
  

  

  and 
  diminished 
  as 
  a 
  linear 
  function 
  of 
  the 
  potential-difference 
  

  

  to 
  the 
  value 
  zero 
  for 
  Y 
  = 
  l*22 
  volts. 
  Usually 
  the 
  current 
  

  

  reached 
  zero 
  for 
  a 
  somewhat 
  smaller 
  voltage 
  than 
  this. 
  The 
  

  

  general 
  effect 
  of 
  both 
  hydrogen 
  and 
  lime 
  on 
  the 
  hot 
  platinum 
  

  

  appears 
  to 
  be 
  to 
  change 
  the 
  law 
  of 
  distribution 
  of 
  energy 
  

  

  among 
  the 
  emitted 
  electrons 
  entirely, 
  and 
  also 
  to 
  change 
  the 
  

  

  average 
  value 
  of 
  the 
  kinetic 
  energy 
  to 
  some 
  extent. 
  In 
  

  

  every 
  case 
  the 
  average 
  value 
  of 
  the 
  kinetic 
  energy 
  was 
  found 
  

  

  to 
  be 
  greater 
  than 
  what 
  it 
  would 
  have 
  been 
  for 
  pure 
  platinum 
  

  

  at 
  the 
  same 
  temperature 
  in 
  air. 
  This 
  change 
  is, 
  comparatively 
  

  

  speaking, 
  not 
  very 
  great. 
  The 
  greatest 
  increase 
  recorded 
  in 
  

  

  our 
  experiments 
  amounted 
  to 
  about 
  twice 
  the 
  value 
  for 
  

  

  platinum 
  alone. 
  

  

  It 
  has 
  been 
  pointed 
  out 
  that 
  the 
  normal 
  behaviour 
  of 
  the 
  

   strip 
  was 
  also 
  deranged 
  if 
  the 
  hot 
  metal 
  was 
  subjected 
  to 
  the 
  

   action 
  of 
  a 
  strong 
  electric 
  field 
  at 
  any 
  time. 
  In 
  this 
  case 
  

   both 
  the 
  law 
  of 
  distribution 
  of 
  energy 
  and 
  the 
  average 
  value 
  

   of 
  the 
  latter 
  appear 
  to 
  be 
  entirely 
  changed. 
  This 
  peculiar 
  

   state 
  of 
  the 
  metal 
  can 
  be 
  got 
  rid 
  of 
  very 
  rapidly 
  by 
  heating- 
  

   it 
  for 
  a 
  short 
  time 
  to 
  a 
  high 
  temperature. 
  After 
  this 
  treat- 
  

   ment 
  the 
  current 
  against 
  the 
  potential 
  again 
  obeys 
  the 
  formula 
  

  

  log 
  e 
  i 
  — 
  log 
  c 
  i 
  = 
  -jjTj 
  V 
  with 
  the 
  same 
  value 
  of 
  the 
  coefficient 
  

  

  tj 
  as 
  in 
  the 
  normal 
  case. 
  

   Jtt 
  

  

  The 
  value 
  of 
  II 
  calculated 
  from 
  eight 
  different 
  series 
  of 
  

   experiments 
  which 
  have 
  been 
  selected 
  as 
  illustrating 
  all 
  the 
  

   different 
  conditions 
  under 
  which 
  the 
  linear 
  relation 
  between 
  

   log 
  i 
  and 
  V 
  was 
  found 
  to 
  be 
  satisfied 
  are 
  given 
  in 
  the 
  accom- 
  

   panying 
  table. 
  It 
  will 
  be 
  observed 
  that 
  other 
  conditions 
  

   besides 
  the 
  previous 
  treatment 
  of 
  the 
  hot 
  metal 
  were 
  varied 
  

   during 
  the 
  experiments. 
  The 
  pressure 
  of 
  the 
  gas 
  varied 
  from 
  

   *006 
  to 
  '06 
  mm., 
  the 
  temperature 
  from 
  1473 
  to 
  1840 
  ab- 
  

   lute, 
  and 
  the 
  maximum 
  current 
  from 
  3 
  x 
  10 
  -12 
  to 
  4*7 
  X 
  10 
  -12 
  

   ampere. 
  The 
  last 
  series 
  in 
  the 
  table 
  was 
  obtained 
  after 
  the 
  

   hot 
  metal 
  had 
  been 
  put 
  into 
  the 
  peculiar 
  state 
  already 
  de- 
  

   scribed 
  by 
  charging 
  the 
  upper 
  plate 
  with 
  a 
  high 
  negative 
  

  

  