﻿G. 
  F. 
  Becker 
  — 
  Computing 
  Diffusion. 
  

  

  285 
  

  

  In 
  the 
  last 
  line 
  I 
  have 
  shown 
  the 
  product 
  /cjjl% 
  which 
  evi- 
  

   dently 
  varies 
  slowly 
  and 
  irregularly. 
  Expressed 
  in 
  two 
  figures 
  

   the 
  average 
  of 
  the 
  two 
  sulphates 
  gives 
  0*22 
  ; 
  the 
  average 
  of 
  

   the 
  three 
  chlorides 
  gives 
  0*22 
  ; 
  the 
  average 
  of 
  the 
  five 
  alkaline 
  

   salts 
  gives 
  0*22 
  ; 
  the 
  average 
  for 
  the 
  seven 
  compounds 
  is 
  022. 
  

   The 
  average 
  for 
  the 
  three 
  potassium 
  salts 
  on 
  the 
  other 
  hand 
  is 
  

   only 
  0'20, 
  and 
  the 
  average 
  for 
  the 
  two 
  sodium 
  salts 
  is 
  0*24. 
  

  

  The 
  variation 
  of 
  /c/jl' 
  from 
  a 
  single 
  value 
  is 
  perhaps 
  not 
  

   greater 
  than 
  might 
  be 
  expected 
  from 
  the 
  data 
  on 
  diffusivity 
  

   (which, 
  as 
  Mr. 
  Schuhmeister 
  himself 
  points 
  out, 
  accord 
  only 
  

   approximately) 
  if 
  fc/j, 
  2 
  were 
  really 
  a 
  constant. 
  It 
  is 
  clear 
  that 
  

   the 
  hypothesis 
  — 
  diffusivity 
  is 
  inversely 
  proportional 
  to 
  the 
  

   square 
  of 
  the 
  viscosity 
  for 
  uniform 
  temperature 
  and 
  concentra- 
  

   tion, 
  expresses 
  approximately 
  the 
  facts 
  for 
  these 
  seven 
  com- 
  

   pounds. 
  The 
  number 
  of 
  compounds 
  is 
  small, 
  but 
  it 
  embraces 
  

   salts 
  of 
  four 
  bases 
  and 
  of 
  four 
  acids 
  showing 
  rather 
  a 
  wide 
  

   range 
  of 
  diffusivities 
  and 
  of 
  viscosities. 
  The 
  probability 
  that 
  

   the 
  accord 
  is 
  a 
  mere 
  coincidence 
  seems 
  to 
  me 
  extremely 
  slight, 
  

   and 
  I 
  infer 
  that 
  the 
  hypothesis 
  just 
  stated 
  probably 
  expresses, 
  

   at 
  least 
  roughly, 
  the 
  relations 
  of 
  diffusivity 
  to 
  viscosity 
  for 
  an 
  

   important 
  class 
  of 
  compounds. 
  Should 
  it 
  prove 
  that 
  solutions 
  

   such 
  as 
  rock 
  magmas 
  are 
  to 
  be 
  included 
  in 
  this 
  class, 
  it 
  would 
  

   greatly 
  facilitate 
  the 
  discussion 
  of 
  rock 
  differentiation. 
  Some 
  

   approach 
  to 
  a 
  quantitative 
  determination 
  of 
  the 
  viscosity 
  of 
  

   lavas 
  might 
  be 
  attained. 
  Direct 
  investigation 
  of 
  their 
  dif- 
  

   fusivity 
  would 
  seem 
  impossible. 
  

  

  

  Liquids 
  

  

  diffusing 
  into 
  wo 
  

  

  ter. 
  

  

  

  

  

  

  Solution 
  of 
  

  

  Temp. 
  

  

  Concentration. 
  

  

  1 
  

  

  

  K 
  

  

  Authority. 
  

  

  Chlorhydric 
  acid, 
  

  

  11° 
  

  

  lHCl/7-l7H' 
  2 
  2 
  

  

  671 
  

  

  •000 
  

  

  030 
  

  

  91 
  " 
  

  

  

  u 
  

  

  ll-° 
  v 
  

  

  1HC1/I08-4H 
  2 
  1 
  

  

  837 
  

  

  000 
  

  

  021 
  

  

  26 
  

  

  ^ 
  

  

  " 
  

  

  o-° 
  

  

  1HC 
  

  

  L/6 
  86H 
  2 
  2 
  

  

  080 
  

  

  000 
  

  

  024 
  

  

  07 
  

  

  

  Sulphuric 
  acid, 
  

  

  7-5° 
  

  

  lH 
  2 
  S0 
  4 
  /685-7H 
  2 
  1 
  

  

  042 
  

  

  000 
  

  

  012 
  

  

  06 
  

  

  !( 
  

  

  8-° 
  

  

  1H 
  2 
  S0 
  4 
  /362H 
  2 
  1 
  

  

  008 
  

  

  000 
  

  

  Oil 
  

  

  67 
  

  

  c£ 
  

  

  " 
  

  

  13-° 
  

  

  lH 
  2 
  S0 
  4 
  /35-4H 
  2 
  1 
  

  

  244 
  

  

  000 
  

  

  014 
  

  

  40 
  

  

  

  Sodium 
  chloride, 
  

  

  7-r 
  

  

  •147 
  

  

  85 
  g. 
  per 
  cm 
  3 
  

  

  810 
  

  

  000 
  

  

  009 
  

  

  38 
  : 
  

  

  

  " 
  

  

  8-3° 
  

  

  •322 
  

  

  38 
  

  

  798 
  

  

  000 
  

  

  009 
  

  

  24 
  

  

  

  n 
  

  

  14-° 
  

  

  •139 
  

  

  75 
  

  

  9015 
  

  

  000 
  

  

  010 
  

  

  43 
  

  

  

  " 
  (Mean), 
  

  

  io-° 
  

  

  •10 
  

  

  

  840 
  

  

  000 
  

  

  009 
  

  

  72 
  

  

  

  Sodium 
  carbonate, 
  

  

  55° 
  

  

  •099 
  

  

  86 
  

  

  319 
  

  

  000 
  

  

  003 
  

  

  69 
  

  

  

  " 
  

  

  9-5° 
  

  

  •134 
  

  

  03 
  " 
  . 
  

  

  375 
  

  

  000 
  

  

  004 
  

  

  34 
  

  

  

  " 
  

  

  20-5° 
  

  

  •182 
  

  

  42 
  

  

  613 
  

  

  000 
  

  

  007 
  

  

  10 
  

  

  :-! 
  

  

  " 
  (Mean), 
  

  

  io-° 
  

  

  •13 
  

  

  

  390 
  

  

  000 
  

  

  004 
  

  

  51 
  

  

  1 
  

  

  Sodium 
  sulphate, 
  

  

  5-3° 
  

  

  •046 
  

  

  19 
  " 
  

  

  614 
  

  

  000 
  

  

  007 
  

  

  11 
  

  

  i 
  

  

  " 
  

  

  10-7° 
  

  

  •073 
  

  

  24 
  " 
  

  

  678 
  

  

  000 
  

  

  007 
  

  

  85 
  

  

  " 
  (Mean), 
  

  

  io-° 
  

  

  •10 
  

  

  

  660 
  

  

  •ooo 
  

  

  007 
  

  

  63 
  

  

  s 
  

  

  Copper 
  sulphate, 
  

  

  8-1° 
  

  

  •177 
  

  

  64 
  

  

  212 
  

  

  000 
  

  

  002 
  

  

  45 
  

  

  O 
  

   U2 
  

  

  (i 
  

  

  8-1° 
  

  

  ■088 
  

  

  57 
  

  

  230 
  

  

  000 
  

  

  002 
  

  

  66 
  

  

  

  u 
  

  

  4'6° 
  

  

  '129 
  

  

  26 
  

  

  203 
  

  

  •ooo 
  

  

  002 
  

  

  35 
  

  

  

  " 
  (Mean), 
  

  

  io-° 
  

  

  •10 
  

  

  

  210 
  

  

  000 
  

  

  002 
  

  

  43 
  

  

  

  Magnesium 
  sulphate, 
  4-5° 
  

  

  •244 
  

  

  05 
  " 
  

  

  209 
  

  

  000 
  

  

  002 
  

  

  42 
  

  

  

  u 
  

  

  9-4° 
  

  

  •309 
  

  

  92 
  

  

  279 
  

  

  000 
  

  

  003 
  

  

  23 
  

  

  

  u 
  

  

  12 
  7° 
  

  

  •311 
  

  

  56 
  " 
  

  

  305 
  

  

  000 
  

  

  003 
  

  

  53 
  

  

  

  " 
  (Mean), 
  

  

  io-° 
  

  

  •10 
  

  

  

  •280 
  

  

  000 
  

  

  003 
  

  

  24^ 
  

  

  

  Cane 
  sugar, 
  

  

  10° 
  

  

  10 
  per 
  cent 
  

  

  456 
  

  

  000 
  

  

  005 
  

  

  28 
  

  

  Graham 
  

   ' 
  Stefan. 
  

  

  Caramel, 
  

  

  10-°-ll 
  

  

  •° 
  10 
  per 
  cent 
  

  

  047 
  

  

  000 
  

  

  000 
  

  

  54 
  

  

  Am. 
  Jour. 
  Sci.- 
  

   20 
  

  

  -Fourth 
  

  

  Series, 
  Yol. 
  Ill, 
  Nc 
  

  

  . 
  16- 
  

  

  -April, 
  

  

  1897 
  

  

  

  