﻿502 
  Mr. 
  W. 
  Sutherland 
  : 
  Another 
  Method 
  of 
  

  

  with 
  values 
  ranging 
  from 
  1 
  to 
  6. 
  In 
  the 
  following 
  table 
  are 
  

   compared 
  the 
  values 
  of 
  A 
  02 
  previously 
  derived 
  in 
  this 
  paper 
  

   from 
  the 
  experimental 
  data 
  with 
  those 
  derived 
  from 
  (10) 
  and 
  

   multiplied 
  by 
  1-18 
  to 
  convert 
  from 
  18° 
  to 
  25°. 
  The 
  values 
  

   of 
  B 
  the 
  limiting 
  volume 
  of 
  a 
  gram-ion 
  are 
  derived 
  from 
  the 
  

   data 
  of 
  Table 
  IV. 
  of 
  Further 
  Studies 
  on 
  Molecular 
  Force 
  

   (Phil. 
  Mag. 
  [5] 
  xxxix. 
  p. 
  1). 
  B 
  for 
  certain 
  elements 
  has 
  the 
  

   approximate 
  values 
  C 
  8, 
  H 
  4, 
  N 
  8, 
  and 
  6. 
  The 
  substances 
  

   are 
  taken 
  in 
  the 
  same 
  order 
  as 
  in 
  Table 
  I. 
  of 
  the 
  present 
  

   paper. 
  

  

  Table 
  II. 
  

  

  B 
  98 
  172 
  121 
  138 
  155 
  176 
  

  

  A 
  02 
  exp 
  38-6 
  540 
  93-6 
  115-3 
  140-9 
  1530 
  

  

  Alcaic. 
  ...... 
  37-8 
  558 
  95-9 
  1173 
  136'3 
  151-9 
  

  

  It 
  ought 
  to 
  be 
  mentioned 
  that 
  the 
  theoretical 
  considerations 
  

   here 
  used 
  have 
  led 
  to 
  very 
  different 
  values 
  for 
  A 
  02 
  from 
  those 
  

   found 
  by 
  Bredig 
  from 
  the 
  application 
  of 
  Ostwald's 
  original 
  

   valency 
  rule 
  and 
  other 
  empirical 
  considerations. 
  For 
  

   example, 
  Bredig 
  gives 
  the 
  ionic 
  conductivity 
  of 
  the 
  ion 
  of 
  

   pyridinepentacarboxylic 
  acid 
  as 
  89*2 
  in 
  the 
  Siemens 
  unit, 
  

   equivalent 
  to 
  94 
  with 
  the 
  ohm, 
  to 
  be 
  compared 
  with 
  the 
  

   140' 
  9 
  of 
  Table 
  II. 
  above, 
  and 
  there 
  are 
  similar 
  differences 
  

   with 
  the 
  other 
  ions 
  though 
  they 
  tend 
  to 
  vanish 
  when 
  v=l. 
  

   The 
  fact 
  that 
  the 
  values 
  A 
  02 
  exp. 
  in 
  Table 
  II. 
  agree 
  

   with 
  those 
  given 
  by 
  (10) 
  is 
  favourable 
  to 
  the 
  conclusion 
  that 
  

   the 
  theory 
  has 
  led 
  to 
  more 
  correct 
  limiting 
  values 
  A 
  02 
  than 
  

   Bredig 
  could 
  obtain 
  at 
  the 
  time 
  when 
  he 
  collected 
  and 
  calcu- 
  

   lated 
  the 
  wealth 
  of 
  data 
  in 
  his 
  paper. 
  

  

  We 
  can 
  now 
  see 
  how 
  the 
  foregoing 
  considerations 
  lead 
  to 
  a 
  

   new 
  method 
  of 
  measuring 
  large 
  molecular 
  masses, 
  or 
  more 
  

   strictly 
  large 
  ionic 
  masses 
  from 
  which 
  the 
  related 
  molecular 
  

   masses 
  can 
  be 
  inferred. 
  If 
  the 
  mass 
  of 
  an 
  ion 
  is 
  large 
  and 
  

   v 
  is 
  not 
  large, 
  then 
  the 
  ionic 
  velocity, 
  say 
  A 
  02 
  , 
  is 
  small 
  com- 
  

   pared 
  with 
  A 
  01 
  + 
  A 
  2, 
  which 
  is 
  measured 
  experimentally 
  and 
  

   is 
  liable 
  to 
  error 
  comparable 
  with 
  A 
  2, 
  thus 
  involving 
  A02 
  in 
  

   very 
  considerable 
  error. 
  But 
  if 
  b 
  is 
  measured 
  and 
  used 
  in 
  

   (8) 
  along 
  with 
  the 
  measured 
  A 
  i-+-A 
  2 
  it 
  gives 
  -A02/V2 
  which 
  in 
  

   (10) 
  gives 
  B. 
  The 
  conditions 
  of 
  the 
  solution 
  are 
  best 
  

   understood 
  by 
  re-writing 
  (10) 
  in 
  the 
  following 
  form 
  : 
  — 
  

  

  v 
  _ 
  0-005471/ 
  0-0097 
  

  

  BiA 
  ~ 
  Btr 
  + 
  1 
  + 
  10'5/B 
  • 
  * 
  * 
  ' 
  l 
  ll 
  > 
  

  

  Here 
  there 
  is 
  a 
  second 
  unknown 
  v 
  in 
  addition 
  to 
  B. 
  But 
  it 
  

   occurs 
  as 
  factor 
  of 
  a 
  term 
  which 
  is 
  small 
  when 
  v 
  is 
  small. 
  So, 
  

   the 
  values 
  of 
  B 
  can 
  be 
  calculated 
  for 
  such 
  small 
  values 
  of 
  v 
  

  

  