﻿the 
  Ions 
  of 
  Gases. 
  351 
  

  

  Thus 
  we 
  transform 
  (13) 
  to 
  

  

  ,,Mi'2B2/3(i 
  + 
  C7288) 
  = 
  106-9 
  (14) 
  

  

  wliicli 
  is 
  the 
  desired 
  equation 
  for 
  finding 
  C^ 
  from 
  a 
  single 
  

   measurement 
  of 
  u 
  for 
  a 
  substance 
  and 
  its 
  known 
  values 
  of 
  

   M 
  and 
  B. 
  The 
  values 
  of 
  u 
  have 
  been 
  collected 
  by 
  J. 
  J. 
  

   Thomsou 
  in 
  his 
  book 
  on 
  ' 
  The 
  Conduction 
  of 
  Electricity 
  

   through 
  Gases/ 
  and 
  by 
  Wellisch 
  with 
  new 
  determinations 
  of 
  

   his 
  own 
  for 
  a 
  number 
  of 
  vapours, 
  in 
  a 
  paper 
  read 
  before 
  the 
  

   Austr. 
  Assoc. 
  Adv. 
  Sc. 
  Jan. 
  1909. 
  There 
  is 
  a 
  difficulty 
  in 
  

   comparing 
  the 
  values 
  of 
  B 
  when 
  these 
  are 
  arrived 
  at 
  by 
  

   different 
  methods 
  for 
  different 
  substances. 
  This 
  can 
  be 
  

   seen 
  by 
  comparing 
  the 
  results 
  of 
  two 
  methods 
  for 
  one 
  

   substance, 
  for 
  example, 
  CI2. 
  For 
  this 
  gas 
  its 
  viscosity 
  gives 
  

   2a 
  = 
  3'13 
  X 
  10"^ 
  and 
  so 
  B 
  = 
  27*4, 
  whereas 
  in 
  the 
  inorganic 
  

   chlorides 
  as 
  well 
  as 
  in 
  the 
  organic 
  B 
  for 
  GI2 
  is 
  38 
  (Phil. 
  Mag. 
  

   [5] 
  xxxix. 
  p. 
  1). 
  It 
  cannot 
  be 
  assumed 
  that 
  the 
  value 
  of 
  

   B 
  for 
  CI 
  in 
  CI2 
  is 
  necessarily 
  the 
  same 
  as 
  that 
  for 
  CI 
  in 
  

   compounds, 
  but 
  I 
  think 
  the 
  chief 
  part 
  of 
  the 
  discrepancy 
  

   between 
  27*4 
  and 
  38 
  is 
  to 
  be 
  traced 
  to 
  the 
  assumption 
  that 
  

   molecules 
  of 
  a 
  gas 
  can 
  still 
  be 
  treated 
  as 
  spheres 
  while 
  they 
  

   are 
  in 
  collision. 
  The 
  kinetic 
  theory 
  of 
  gases 
  gives 
  us 
  2a 
  as 
  

   the 
  distance 
  between 
  the 
  centres 
  of 
  two 
  molecules 
  while 
  they 
  

   are 
  in 
  collision, 
  which 
  may 
  be 
  less 
  than 
  the 
  mean 
  diameter 
  

   of 
  either. 
  For 
  this 
  reason 
  I 
  shall 
  present 
  the 
  data 
  for 
  

   discussion 
  in 
  two 
  ways, 
  first 
  using 
  only 
  the 
  values 
  of 
  B 
  

   derivable 
  from 
  the 
  kinetic 
  theory 
  of 
  gases, 
  and 
  second 
  only 
  

   those 
  derived 
  from 
  the 
  apparent 
  limiting 
  volumes 
  of 
  liquids 
  

   and 
  solids. 
  

  

  H, 
  

   2rtxlOio 
  181 
  

  

  ICMJB 
  528 
  

  

  \{)u 
  73 
  

  

  M 
  2 
  

  

  100C7288 
  241 
  

  

  100C'(2a)-7288 
  731 
  

  

  The 
  values 
  given 
  for 
  lOw 
  are 
  ^(u^ 
  + 
  u^), 
  that 
  for 
  He 
  being 
  

   obtained 
  by 
  Franck 
  and 
  Pohl 
  {Ann. 
  d. 
  Ph. 
  Beihl. 
  xxxi. 
  

   1907, 
  p. 
  1133), 
  namely 
  u^ 
  = 
  5-09 
  and 
  u^ 
  = 
  6*31. 
  To 
  this 
  

   monatomic 
  gas 
  the 
  formula 
  (14) 
  for 
  diatomic 
  and 
  compound 
  

  

  

  Table 
  II. 
  

  

  

  

  

  

  He. 
  

  

  N,. 
  

  

  0, 
  

  

  CI, 
  

  

  CO. 
  

  

  CO,. 
  

  

  N,0. 
  

  

  160 
  

  

  246 
  

  

  225 
  

  

  313 
  

  

  228 
  

  

  241 
  

  

  277 
  

  

  368 
  

  

  1330 
  

  

  1026 
  

  

  2742 
  

  

  1066 
  

  

  1254 
  

  

  1912 
  

  

  57 
  

  

  16 
  

  

  16 
  

  

  10 
  

  

  10-7 
  

  

  7-9 
  

  

  8-2 
  

  

  4 
  

  

  28 
  

  

  32 
  

  

  71 
  

  

  28 
  

  

  44 
  

  

  44 
  

  

  293 
  

  

  125 
  

  

  133 
  

  

  39-5 
  

  

  290 
  

  

  278 
  

  

  175 
  

  

  G98 
  

  

  702 
  

  

  708 
  

  

  359 
  

  

  1404 
  

  

  1501 
  

  

  1251 
  

  

  