﻿Positive 
  Ions 
  emitted 
  from 
  various 
  Hot 
  Bodies. 
  

   Summary 
  of 
  Results. 
  

  

  665 
  

  

  Kadiator 
  material. 
  

  

  Form 
  of 
  

   iRadiator. 
  

  

  Gold(l) 
  

  

  Gold(2) 
  

  

  Silver(l) 
  

  

  Silver(2) 
  , 
  

  

  Palladium 
  , 
  

  

  Aluminium 
  phospbate(l) 
  

   Aluminium 
  phosphate 
  (2) 
  

  

  Nickel 
  

  

  Iron(l) 
  

  

  Iron 
  (2) 
  

  

  Iron 
  (3) 
  

  

  Platinum 
  

  

  Tungsten 
  

  

  Tantalum 
  

  

  Tantalum 
  

  

  Osmium 
  

  

  disk 
  

  

  disk 
  

  

  disk 
  

   disk 
  

   disk 
  

   disk 
  

   disk 
  

   strip 
  

   disk 
  

   disk 
  

   disk 
  

   wire 
  

   filament 
  

   filament 
  

  

  strip 
  

   filament 
  

  

  Temper- 
  

   ature, 
  

   absolute, 
  

  

  Current 
  i 
  

   at 
  zero 
  j 
  Vacuum 
  

   potential 
  Pressure, 
  

  

  J 
  1030 
  1 
  

   1 
  973] 
  

   / 
  11901 
  

   11163/ 
  

   1020 
  

   1150 
  

   1170 
  

   1230 
  

   1170 
  

   1120 
  

   1100 
  

   1100 
  

   1240 
  

   1695 
  

   1150 
  

   1050 
  

   1050 
  

   1120 
  

  

  10 
  

  

  60-0 
  

  

  •8 
  

  

  35-0 
  

  

  250 
  

  

  100-0 
  

  

  1200 
  

  

  2-5 
  

  

  1-0 
  

  

  •8 
  

  

  10 
  

   •7 
  

  

  1-0 
  

   30 
  

  

  •007 
  

  

  •01 
  

  

  •002 
  

   •008 
  

   •04 
  

  

  •006 
  

   •003 
  

  

  •005 
  

   •01 
  

  

  •0003 
  

   •0005 
  

   •002 
  

  

  Gas 
  

  

  Constant, 
  

  

  E/103 
  

  

  4-2 
  

  

  3-9 
  

  

  3-0 
  

   2-9 
  

   3-4 
  

   3-9 
  

   3-4 
  

   3-6 
  

   4-6 
  

   5-2 
  

   4-4 
  

   5^1 
  

   5-1 
  

   9-6 
  

   30 
  

   2-5 
  

  

  Discussion 
  of 
  Results. 
  

  

  In 
  interpreting 
  the 
  results 
  of 
  the 
  measurements 
  it 
  is 
  

   necessary 
  to 
  consider 
  to 
  what 
  extent 
  they 
  are 
  reliable. 
  In 
  

   our 
  discussion 
  we 
  have 
  a 
  right 
  to 
  discard 
  the 
  values 
  obtained 
  

   with 
  tungsten, 
  osmium, 
  and 
  with 
  tantalum 
  and 
  platinum 
  

   wires, 
  because 
  the 
  form 
  of 
  the 
  thermionic 
  radiator 
  is 
  quite 
  

   different 
  from 
  that 
  required 
  by 
  the 
  theory. 
  There 
  is, 
  how- 
  

   ever, 
  no 
  obvious 
  reason 
  why 
  the 
  results 
  with 
  filaments 
  should 
  

   show 
  such 
  wide 
  variations 
  in 
  the 
  values 
  of 
  R. 
  The 
  obser- 
  

   vations 
  with 
  osmium 
  were 
  taken 
  after 
  several 
  hours' 
  heating, 
  

   and 
  negative 
  ions 
  may 
  have 
  been 
  emitted 
  simultaneously 
  

   with 
  the 
  positive 
  ions. 
  This 
  might 
  account 
  for 
  the 
  much 
  

   lower 
  value 
  of 
  E. 
  than 
  those 
  obtained 
  with 
  the 
  other 
  filaments. 
  

   The 
  other 
  wires 
  all 
  gave 
  values 
  distinctly 
  higher 
  than 
  those 
  

   obtained 
  with 
  plane 
  surfaces 
  of 
  metal, 
  and 
  it 
  seems 
  reasonable 
  

   to 
  attribute 
  the 
  discrepancy 
  to 
  the 
  curvature 
  of 
  the 
  surface 
  

   used. 
  

  

  In 
  the 
  calculations 
  of 
  the 
  mean 
  energy 
  certain 
  h3^potheses 
  

   are 
  assumed, 
  and 
  strictly 
  speaking 
  we 
  are 
  justified 
  in 
  these 
  

   hypotheses 
  and 
  calculations 
  only 
  by 
  virtue 
  of 
  the 
  result. 
  

   The 
  theoretical 
  value 
  of 
  the 
  gas 
  constant 
  is 
  taken 
  from 
  the 
  

   equations 
  ^6 
  = 
  ^nmv'^ 
  and 
  l\6=pv^ 
  and 
  is 
  easily 
  calculated 
  to 
  

   be 
  3*7x10^ 
  for 
  a 
  unit 
  volume 
  of 
  gas 
  under 
  standard 
  con- 
  

   -flitions 
  of 
  pressure 
  and 
  temperature. 
  The 
  lowest 
  experimental 
  

  

  Phil. 
  Mag. 
  S. 
  6. 
  Vol. 
  18. 
  No. 
  106. 
  Oct. 
  1909. 
  2 
  Y 
  

  

  