﻿472 
  Profs. 
  Cooke 
  and 
  Richardson 
  on 
  Absorption 
  of 
  

  

  which 
  »i/H 
  = 
  about 
  100. 
  This 
  may 
  point 
  to 
  an 
  undiscovered 
  

   common 
  impurity 
  which 
  gives 
  rise 
  to 
  heavy 
  negative 
  ions, 
  

   but 
  the 
  reliability 
  and 
  accuracy 
  of 
  the 
  measurements 
  of 
  m/H 
  

   for 
  these 
  heavy 
  ions 
  are 
  insufficient 
  to 
  establish 
  such 
  a 
  con- 
  

   clusion 
  at 
  present. 
  

  

  In 
  conclusion 
  I 
  wish 
  to 
  thank 
  my 
  assistant, 
  Mr. 
  E. 
  S. 
  

   Taylerson, 
  for 
  his 
  help 
  in 
  carrying 
  out 
  these 
  experiments. 
  

  

  Palmer 
  Physical 
  Laboratoiy, 
  

  

  XXXVI. 
  The 
  Absorption 
  of 
  Heat 
  produced 
  by 
  the 
  Emission 
  

   of 
  Ions 
  from 
  Hot 
  Bodies 
  : 
  II. 
  By 
  H. 
  L. 
  CoOKE, 
  Assistant 
  

   Professor 
  of 
  Physics, 
  and 
  0. 
  W. 
  RlCHAKDSON, 
  F.R.S., 
  

   Professor 
  of 
  Physics 
  , 
  Princeton 
  University 
  *. 
  

  

  IN 
  a 
  recent 
  paper 
  t 
  we 
  have 
  shown 
  that 
  when 
  a 
  current 
  of 
  

   negative 
  electrons 
  is 
  allowed 
  to 
  flow 
  from 
  a 
  heated 
  

   filament 
  of 
  osmium, 
  there 
  is 
  an 
  absorption 
  of 
  heat 
  which 
  is 
  

   equal 
  in 
  amount 
  to 
  the 
  energy 
  required 
  to 
  drive 
  the 
  escaping 
  

   electrons 
  through 
  a 
  potential 
  difference 
  of 
  4*7 
  volts. 
  The 
  

   present 
  paper 
  deals 
  with 
  similar 
  experiments 
  which 
  we 
  have 
  

   made 
  with 
  lime-coated 
  platinum 
  wires 
  and 
  with 
  tungsten 
  

   wires. 
  Xeither 
  the 
  apparatus 
  used 
  nor 
  the 
  method 
  of 
  

   experimenting 
  has 
  been 
  changed 
  in 
  any 
  important 
  particular, 
  

   so 
  that 
  it 
  will 
  be 
  sufficient 
  to 
  refer 
  to 
  the 
  former 
  paper 
  for 
  

   their 
  description 
  and 
  simply 
  to 
  record 
  the 
  results 
  which 
  have 
  

   been 
  obtained. 
  We 
  shall 
  also 
  use 
  the 
  same 
  notation 
  as 
  

   before. 
  

  

  The 
  behaviour 
  of 
  lime-coated 
  platinum 
  wires 
  is 
  of 
  par- 
  

   ticular 
  interest 
  since 
  it 
  was 
  with 
  this 
  combination 
  of 
  sub- 
  

   stances 
  that 
  the 
  first 
  attempts 
  were 
  made, 
  by 
  Wehnelt 
  and 
  

   his 
  pupils 
  J, 
  to 
  detect 
  the 
  effect 
  under 
  investigation. 
  Our 
  

   experiments 
  agree 
  with 
  theirs 
  in 
  showing 
  that 
  the 
  phenomena 
  

   exhibited 
  by 
  lime-coated 
  platinum 
  wires 
  do 
  not 
  exhibit 
  any 
  

   evident 
  relationship 
  with 
  the 
  theory 
  of 
  these 
  effects. 
  Their 
  

   behaviour 
  is 
  quite 
  different 
  from 
  that 
  of 
  the 
  osmium 
  and 
  

   tungsten 
  wires. 
  In 
  the 
  case 
  of 
  the 
  latter 
  substances 
  the 
  

  

  * 
  Communicated 
  by 
  the 
  Authors. 
  

   t 
  Phil. 
  Mag. 
  vol. 
  xxv. 
  (1913) 
  p. 
  624. 
  

  

  t 
  Cf. 
  Wehnelt 
  & 
  Jentzsch, 
  Ann. 
  der 
  Phys. 
  vol. 
  xxviii. 
  p. 
  537 
  (1909), 
  

   and 
  Schneider, 
  Ann. 
  der 
  Phys. 
  vol. 
  xxxvii. 
  p. 
  569 
  (1912). 
  

  

  