﻿Ionic 
  Velocities, 
  and 
  Atomic 
  Sizes, 
  175 
  

  

  zero, 
  which 
  can 
  be 
  closely 
  estimated, 
  ^equation 
  (15) 
  would 
  

   become 
  a 
  definite 
  one 
  for 
  a 
  l 
  the 
  atomic 
  radius. 
  For 
  an 
  ion 
  

   of 
  valency 
  v, 
  e 
  l 
  must 
  be 
  replaced 
  by 
  vV 
  and 
  ^o 
  by 
  v{K 
  and 
  

   (15) 
  becomes 
  

  

  l 
  \ 
  = 
  ^K 
  /69n 
  ? 
  a 
  l 
  K 
  1 
  (16) 
  

  

  We 
  can 
  derive 
  values 
  of 
  K 
  T 
  from 
  the 
  relation 
  KjsssNx 
  2 
  , 
  where 
  

   N 
  x 
  is 
  the 
  index 
  of 
  refraction 
  of 
  the 
  stuff 
  of 
  the 
  atom. 
  In 
  

   a 
  recent 
  paper 
  (" 
  The 
  Cause 
  of 
  the 
  Structure 
  of 
  Spectra/' 
  

   Phil. 
  Mag. 
  [6] 
  ii.) 
  I 
  have 
  given 
  values 
  of 
  Nj 
  for 
  a 
  number 
  

   of 
  metals 
  of 
  known 
  density, 
  which 
  may 
  be 
  taken 
  to 
  be 
  the 
  

   limiting 
  density, 
  and 
  so 
  the 
  data 
  are 
  to 
  hand 
  for 
  calculating 
  

   cii 
  for 
  a 
  number 
  of 
  elements. 
  But 
  before 
  proceeding 
  to 
  

   absolute 
  values 
  we 
  can 
  test 
  how 
  the 
  equation 
  behaves 
  

   relatively 
  for 
  a 
  number 
  of 
  elements. 
  As 
  e"\ 
  rj, 
  and 
  K 
  are 
  

   the 
  same 
  for 
  all 
  ions 
  when 
  we 
  deal 
  with 
  infinitely 
  dilute 
  

   aqueous 
  solutions, 
  we 
  must 
  have 
  1 
  \ 
  a 
  l 
  K 
  l 
  /v 
  the 
  same 
  for 
  all 
  

   ions. 
  To 
  test 
  this 
  relation 
  we 
  gather 
  for 
  several 
  atoms 
  and 
  

   radicals 
  in 
  Table 
  III. 
  the 
  values 
  of 
  N 
  1? 
  and 
  of 
  B 
  which 
  is 
  

   the 
  limiting 
  volume 
  o£ 
  a 
  gramme-atom 
  or 
  gramme-radical, 
  

   of 
  jXq 
  according 
  to 
  Kohlrausch, 
  and 
  of 
  1 
  \B 
  ll 
  ' 
  s 
  Ni/v 
  which 
  

   by 
  (16) 
  is 
  to 
  be 
  constant. 
  The 
  values 
  of 
  N 
  x 
  are 
  derived 
  from 
  

   the 
  refraction 
  formula 
  (/i 
  — 
  l)M/p= 
  (N 
  — 
  1)B 
  with 
  the 
  values 
  

   of 
  (n-1'M./p 
  given 
  in 
  the 
  text-books 
  as 
  atomic 
  refractions 
  

   (see 
  for 
  example 
  L. 
  Meyer's 
  f 
  Modern 
  Chemistry'), 
  and 
  with 
  

   values 
  of 
  B 
  as 
  given 
  in 
  " 
  Further 
  Studies 
  on 
  Molecular 
  

   Force" 
  (Phil. 
  Mag. 
  [5] 
  xxxix.) 
  and 
  reproduced 
  here. 
  v 
  = 
  2 
  

   for 
  Mg, 
  Ca, 
  Sr, 
  Ba, 
  and 
  Zn, 
  and 
  v 
  = 
  l 
  for 
  the 
  rest. 
  

  

  Table 
  III. 
  

  

  Li. 
  Na. 
  K. 
  Eb. 
  Cs. 
  Mg. 
  Ca. 
  Sr. 
  Ba. 
  Zn. 
  

  

  T 
  X 
  (1 
  ... 
  35-5 
  44-4 
  65-3 
  67*3 
  67'8 
  48 
  53 
  54 
  573 
  47*5 
  

  

  B... 
  2 
  7-4 
  18-6 
  344 
  56 
  56 
  8-6 
  106 
  16-6 
  10-6 
  

  

  N... 
  2-9 
  1-65 
  1-44 
  141 
  1-24 
  225 
  221 
  228 
  195 
  1-96. 
  

  

  .XqBVW'/p 
  375 
  235 
  360 
  435 
  400 
  215 
  265 
  310 
  277 
  200 
  

  

  R 
  CI. 
  Br. 
  I. 
  H. 
  OH. 
  

  

  X 
  X 
  46-1 
  65-9 
  67 
  '5 
  66-7 
  318 
  174 
  

  

  B 
  9 
  19 
  26 
  36 
  4-5 
  95 
  

  

  N 
  116 
  1-56 
  1-65 
  1-76 
  1-37 
  1'44 
  

  

  iXoBi/SN 
  2 
  v 
  ... 
  130 
  430 
  545 
  680 
  980 
  765 
  

  

  HCOO. 
  CH 
  3 
  COO. 
  C,H 
  5 
  COO. 
  C 
  3 
  H 
  7 
  COO. 
  C.H.COO. 
  C 
  5 
  H 
  u 
  COCK 
  

  

  t 
  X 
  47-2 
  35-4 
  " 
  31-8 
  28-3 
  26-5 
  25-3 
  

  

  B 
  24-5 
  42 
  59-5 
  77 
  94-5 
  112 
  

  

  ]S 
  T 
  1-494 
  1-469 
  1-458 
  1*454 
  T450 
  1-448 
  

  

  ,\ 
  n 
  Bi'3N 
  2 
  /r 
  • 
  305 
  265 
  264 
  255 
  253 
  256 
  

  

  