﻿tlie 
  Ions 
  of 
  Gases. 
  353 
  

  

  spicuously 
  small, 
  as 
  in 
  the 
  case 
  of 
  CI2, 
  and 
  so 
  also 
  is 
  

   10B23CV288 
  conspicuously 
  small. 
  But 
  in 
  C2H5CI 
  this 
  effect 
  

   does 
  not 
  appear. 
  In 
  aldehyde, 
  alcohol, 
  and 
  acetone, 
  which 
  

   are 
  known 
  to 
  be 
  associative 
  liquids, 
  the 
  potential 
  energy 
  and 
  

   its 
  product 
  by 
  B^'^ 
  are 
  both 
  large. 
  The 
  other 
  substances 
  of 
  

   the 
  table 
  give 
  values 
  of 
  10B2/3C7288 
  near 
  to 
  240, 
  except 
  

   C5H12, 
  which 
  has 
  the 
  value 
  165. 
  This 
  240 
  is 
  nearly 
  double 
  

   138'5 
  found 
  for 
  compound 
  gases 
  in 
  the 
  last 
  table. 
  We 
  learn 
  

   then, 
  that 
  on 
  the 
  whole 
  B^/^C' 
  increases 
  with 
  the 
  liquefiability 
  

   of 
  a 
  substance. 
  For 
  the 
  substances 
  of 
  Table 
  III. 
  the 
  values 
  

   of 
  10007^88 
  are 
  only 
  apparent 
  values 
  of 
  the 
  potential 
  

   energy, 
  since 
  our 
  theory 
  would 
  apply 
  to 
  them 
  strictly 
  only 
  

   at 
  temperatures 
  above 
  the 
  critical. 
  Probably 
  the 
  values 
  of 
  

   10007^88 
  in 
  Table 
  III. 
  are 
  roughly 
  proportional 
  to 
  the 
  

   desired 
  potential 
  energies. 
  As 
  stated 
  above, 
  the 
  Table 
  

   has 
  been 
  drawn 
  up 
  to 
  give 
  only 
  preliminary 
  information. 
  

   Returning 
  to 
  the 
  more 
  definite 
  facts 
  of 
  Table 
  II., 
  we 
  see 
  that 
  

   constancy 
  of 
  B^^C^ 
  would 
  imply 
  that 
  the 
  potential 
  energy 
  of 
  

   ion 
  and 
  molecule 
  in 
  contact 
  varies 
  inversely 
  as 
  the 
  square 
  

   of 
  the 
  distance 
  between 
  their 
  centres. 
  Now 
  one 
  of 
  the 
  

   main 
  results 
  found 
  in 
  my 
  studies 
  on 
  molecular 
  attraction 
  

   is 
  this, 
  that 
  molecules 
  attract 
  one 
  another 
  as 
  though 
  

   each 
  were 
  a 
  uniformly 
  electrized 
  sphere 
  of 
  total 
  electric 
  

   moment 
  E. 
  If 
  an 
  ion 
  of 
  charge 
  e 
  and 
  volume 
  half 
  that 
  of 
  

   the 
  molecule 
  were 
  in 
  contact 
  with 
  the 
  molecule 
  in 
  the 
  

   position 
  of 
  minimum 
  potential 
  energy, 
  that 
  energy 
  would 
  

   be 
  proportional 
  to 
  — 
  E^/B^''^. 
  This 
  shows 
  the 
  probable 
  

   origin 
  of 
  the 
  constancy 
  of 
  B^/^^C. 
  But 
  I 
  have 
  shown 
  that 
  in 
  

   most 
  cases 
  E 
  is 
  proportional 
  to 
  B. 
  So 
  it 
  appears 
  that, 
  if 
  the 
  

   ion 
  were 
  able 
  to 
  turn 
  the 
  whole 
  field 
  of 
  electrization 
  of 
  the 
  

   molecule 
  so 
  that 
  its 
  axis 
  passes 
  through 
  the 
  ion 
  in 
  the 
  

   position 
  of 
  minimum 
  potential 
  energy, 
  C 
  would 
  be 
  propor- 
  

   tional 
  to 
  B/B^'^, 
  that 
  is 
  to 
  W^l^, 
  instead 
  of 
  to 
  l/B^/^, 
  as 
  we 
  have 
  

   found 
  above 
  to 
  be 
  the 
  case 
  for 
  Hg, 
  He, 
  N2, 
  and 
  O2. 
  It 
  

   appears 
  then 
  that 
  instead 
  of 
  the 
  E 
  which 
  is 
  proportional 
  to 
  

   B 
  we 
  have 
  to 
  do 
  with 
  another 
  electric 
  moment 
  E' 
  which 
  is 
  

   the 
  same 
  for 
  these 
  four 
  element 
  gases. 
  An 
  ion 
  does 
  not 
  

   turn 
  the 
  whole 
  electric 
  field 
  of 
  a 
  molecule 
  so 
  that 
  its 
  axis 
  

   passes 
  through 
  the 
  ion, 
  but 
  on 
  the 
  average 
  it 
  turns 
  tliat 
  

   electric 
  field 
  so 
  that 
  its 
  component 
  along 
  the 
  line 
  joining 
  the 
  

   centre 
  of 
  ion 
  to 
  centre 
  of 
  molecule 
  is 
  that 
  arising 
  from 
  an 
  

   electric 
  moment 
  E' 
  which 
  is 
  the 
  same 
  for 
  four 
  out 
  of 
  five 
  

   element 
  gases 
  in 
  Table 
  II. 
  The 
  absolute 
  magnitude 
  of 
  this 
  

   moment 
  can 
  be 
  found 
  by 
  means 
  of 
  the 
  following 
  data 
  for 
  

   H2 
  at 
  15° 
  C.^ 
  using 
  4x10^'^ 
  for 
  the 
  number 
  of 
  molecules 
  

  

  