﻿662 
  Dr. 
  F. 
  C. 
  Brown 
  on 
  the 
  Kinetic 
  Energy 
  of 
  the 
  

  

  absolute. 
  The 
  value 
  of 
  the 
  gas 
  constant 
  is 
  calculated 
  to 
  

   be 
  3-6 
  X 
  103. 
  

  

  Tungsten 
  and 
  Osmium. 
  

  

  Because 
  of 
  the 
  difficulty 
  of 
  getting 
  many 
  of 
  the 
  materials 
  

   in 
  the 
  form 
  of 
  a 
  strip, 
  it 
  was 
  thought 
  advisable 
  to 
  try 
  a 
  round 
  

   emittijig 
  surface, 
  such 
  as 
  the 
  surface 
  of 
  a 
  wire 
  or 
  a 
  filament, 
  

   A 
  platinum 
  wire 
  and 
  tungsten, 
  tantalum, 
  and 
  osmium 
  fila- 
  

   ments 
  were 
  substituted 
  for 
  the 
  strip 
  or 
  the 
  disk. 
  At 
  

   1G50 
  degrees 
  absolute 
  a 
  platinum 
  wire 
  'll 
  mm. 
  diameter 
  

   gave 
  the 
  observations 
  represented 
  by 
  curve 
  6 
  (fig. 
  5). 
  For 
  a 
  

   tungsten 
  filament 
  similar 
  observations 
  at 
  1200° 
  absolute 
  gave 
  

   the 
  points 
  marked 
  [•], 
  which 
  are 
  also 
  shown 
  roughly 
  by 
  

   •curve 
  6. 
  The 
  corresponding 
  logarithms 
  of 
  the 
  current 
  are 
  

   shown 
  in 
  curve 
  6 
  h. 
  

  

  The 
  value 
  of 
  the 
  gas 
  constant 
  for 
  the 
  platinum 
  wire 
  was 
  

   6'2 
  X 
  10^ 
  and 
  for 
  the 
  tungsten 
  filament 
  was 
  8*0 
  x 
  10^. 
  We 
  

   might 
  readily 
  ascribe 
  the 
  results 
  to 
  the 
  form 
  of 
  the 
  emitting 
  

   surface 
  were 
  it 
  not 
  for 
  the 
  results 
  from 
  osmium, 
  which 
  show 
  

   the 
  value 
  of 
  the 
  gas 
  constant 
  to 
  be 
  11 
  = 
  2*5 
  xlO^. 
  The 
  ob- 
  

   servations 
  in 
  the 
  case 
  of 
  osmium 
  are 
  shown 
  by 
  curve 
  8 
  and 
  

   the 
  corresponding 
  logarithms 
  in 
  curve 
  %h. 
  

  

  Silver, 
  

  

  The 
  form 
  of 
  the 
  thermionic 
  radiator 
  in 
  the 
  investigations 
  

   with 
  silver^ 
  palladium, 
  aluminium 
  phosphate, 
  and 
  iron 
  was 
  

   that 
  of 
  a 
  disk. 
  The 
  silver 
  disk 
  was 
  of 
  the 
  same 
  dimensions 
  

   as 
  the 
  gold 
  disk 
  previously 
  described. 
  It 
  was 
  welded 
  to 
  a 
  

   palladium 
  strip 
  similar 
  to 
  the 
  way 
  the 
  gold 
  disk 
  was 
  welded 
  

   to 
  the 
  platinum. 
  Two 
  series 
  of 
  observations 
  were 
  taken, 
  

   using 
  the 
  same 
  disk 
  at 
  different 
  temperatures, 
  in 
  which 
  the 
  

   magnitude 
  of 
  the 
  ionic 
  current 
  was 
  44 
  times 
  as 
  large 
  in 
  the 
  

   one 
  case 
  as 
  it 
  was 
  in 
  the 
  other. 
  The 
  mean 
  energy 
  was 
  

   deduced 
  from 
  the 
  curves 
  in 
  the 
  ordinary 
  way. 
  It 
  is 
  given 
  

   by 
  R 
  = 
  3'0xl0^ 
  and 
  2*9 
  x 
  10^. 
  There 
  is 
  no 
  evident 
  reason 
  

   why 
  these 
  results 
  should 
  not 
  be 
  fairly 
  accurate. 
  The 
  

   mechanical 
  adjustment 
  seemed 
  perfect. 
  

  

  Palladium, 
  

  

  Palladium 
  gave 
  quite 
  a 
  large 
  ionization 
  at 
  first. 
  One 
  

   series 
  of 
  observations 
  were 
  taken 
  from 
  a 
  palladium 
  disk 
  at 
  a 
  

   -temperature 
  of 
  1170 
  degrees 
  absolute. 
  The 
  value 
  of 
  R 
  was 
  

   3-4 
  X 
  10^ 
  The 
  amount 
  of 
  gas 
  emitted 
  was 
  also 
  large. 
  

  

  