﻿374 
  Prof. 
  Richardson 
  and 
  Mr. 
  Brown 
  on 
  the 
  Kinetic 
  

  

  as 
  yet 
  to 
  enable 
  much 
  to 
  be 
  said 
  positively 
  as 
  to 
  the 
  causes 
  

   which 
  make 
  the 
  distribution 
  of 
  the 
  energy 
  differ 
  from 
  the 
  

   Maxwell 
  type. 
  There 
  are, 
  however, 
  certain 
  obvious 
  causes 
  

   which 
  might 
  change 
  the 
  distribution 
  of 
  energy. 
  If 
  a 
  double 
  

   layer 
  formed 
  outside 
  the 
  metal, 
  and 
  the 
  direction 
  of 
  the 
  

   electric 
  force 
  in 
  the 
  double 
  layer 
  was 
  such 
  that 
  it 
  tended 
  to 
  

   drive 
  the 
  ions 
  away 
  from 
  the 
  metal, 
  the 
  distribution 
  of 
  

   energy 
  would 
  be 
  altered. 
  Admitting 
  that 
  the 
  free 
  electrons 
  

   inside 
  the 
  metal 
  have 
  the 
  distribution 
  of 
  velocity 
  given 
  by 
  

   Maxwell's 
  law, 
  those 
  which 
  escaped 
  into 
  the 
  double 
  layer 
  

   would 
  also 
  have 
  this 
  distribution 
  provided 
  they 
  were 
  enabled 
  

   to 
  get 
  out 
  by 
  virtue 
  of 
  their 
  kinetic 
  energy 
  overcoming 
  the 
  

   surface 
  forces. 
  All 
  the 
  ions 
  which 
  reached 
  the 
  double 
  layer 
  

   would 
  escape 
  into 
  the 
  region 
  outside, 
  but 
  the 
  value 
  of 
  \mu 
  2 
  

   for 
  each 
  of 
  them 
  would 
  be 
  increased 
  by 
  the 
  work 
  done 
  in 
  

   passing 
  through 
  the 
  layer. 
  Thus, 
  in 
  this 
  simple 
  case, 
  the 
  

   distribution 
  of 
  energy 
  among 
  the 
  emitted 
  particles 
  would 
  be 
  

   that 
  given 
  by 
  Maxwell's 
  law 
  + 
  a 
  constant. 
  If 
  the 
  electrons 
  

   escaping 
  were 
  deflected 
  by 
  collisions 
  with 
  atoms 
  inside 
  the 
  

   double 
  layer 
  itself 
  this 
  simple 
  law 
  of 
  distribution 
  would 
  be 
  

   altered 
  and 
  would 
  become 
  very 
  complex, 
  but 
  in 
  any 
  case 
  we 
  

   should 
  expect 
  that 
  any 
  variation 
  from 
  the 
  normal 
  would 
  

   result 
  in 
  an 
  increase 
  in 
  the 
  average 
  energy 
  of 
  the 
  particles. 
  

   This 
  explanation 
  is 
  supported 
  by 
  the 
  facts, 
  so 
  far 
  as 
  this 
  

   particular 
  conclusion 
  is 
  concerned 
  ; 
  for 
  in 
  all 
  the 
  cases 
  of 
  

   deviation 
  from 
  the 
  type 
  which 
  we 
  have 
  examined 
  the 
  mean 
  

   kinetic 
  energy 
  appeared 
  to 
  be 
  greater 
  than 
  that 
  required 
  by 
  

   Maxwell's 
  law. 
  

  

  The 
  most 
  reasonable 
  way 
  of 
  interpreting 
  the 
  results 
  which 
  

   have 
  been 
  obtained 
  so 
  far 
  appears 
  to 
  us 
  to 
  be 
  to 
  suppose 
  that 
  

   generally 
  speaking 
  the 
  distribution 
  of 
  velocity 
  among 
  the 
  free 
  

   electrons 
  inside 
  the 
  metal 
  is 
  that 
  given 
  by 
  Maxwell's 
  law 
  for 
  

   a 
  molecule 
  of 
  gas 
  at 
  the 
  same 
  temperature 
  as 
  that 
  of 
  the 
  

   metal. 
  That 
  when 
  the 
  electrons 
  which 
  escape 
  simply 
  have 
  

   to 
  do 
  a 
  certain 
  amount 
  of 
  work 
  against 
  surface 
  forces 
  this 
  

   law 
  also 
  holds 
  for 
  the 
  distribution 
  of 
  energy 
  among 
  the 
  

   electrons 
  which 
  have 
  escaped. 
  It 
  seems 
  probable, 
  however, 
  

   that 
  there 
  are 
  a 
  large 
  number 
  of 
  cases 
  of 
  the 
  escape 
  of 
  

   electrons 
  from 
  hot 
  metals 
  when 
  the 
  mechanism 
  is 
  not 
  so 
  

   simple 
  as 
  this. 
  There 
  may 
  for 
  instance 
  be 
  a 
  double 
  layer 
  like 
  

   the 
  one 
  already 
  alluded 
  to 
  ; 
  there 
  is 
  some 
  evidence 
  that 
  the 
  

   very 
  large 
  change 
  produced 
  by 
  absorbed 
  hydrogen 
  on 
  the 
  leak 
  

   from 
  hot 
  platinum 
  may 
  be 
  due 
  to 
  an 
  effect 
  of 
  this 
  kind. 
  It 
  

   is 
  possible 
  also 
  that 
  the 
  expulsion 
  of 
  these 
  electrons 
  in 
  some 
  

   cases 
  is 
  due 
  to 
  a 
  more 
  indirect 
  process. 
  It 
  might 
  for 
  

  

  