﻿Forces 
  produced 
  hy 
  Flowing 
  Solutions. 
  597 
  

  

  to 
  make 
  measurements 
  only 
  with 
  such 
  concentrations 
  that 
  

   the 
  E.M.F. 
  obtained 
  was 
  o£ 
  a 
  higher 
  order 
  of 
  magnitude 
  

   than 
  the 
  error. 
  Hence 
  high 
  concentrations 
  could 
  not 
  be 
  

   used. 
  On 
  the 
  other 
  hand, 
  concentrations 
  of 
  1/10000 
  nor- 
  

   mality 
  must 
  also 
  be 
  avoided 
  because 
  impurities 
  of 
  the 
  water 
  

   can 
  then 
  exert 
  too 
  great 
  an 
  influence, 
  and 
  the 
  value 
  in 
  the 
  

   couducti^-ity 
  becomes 
  too 
  uncertain, 
  so 
  that 
  of 
  the 
  many 
  

   preliminary 
  experiments 
  those 
  between 
  N/5000 
  and 
  N/1500 
  

   were 
  found 
  best 
  : 
  our 
  final 
  experiments 
  were 
  carried 
  out 
  

   between 
  these 
  concentrations 
  in 
  the 
  following 
  manner 
  : 
  — 
  

  

  The 
  solutions 
  used 
  were 
  prepared 
  synthetically; 
  in 
  each 
  

   case 
  a 
  definite 
  amount 
  of 
  solution 
  of 
  known 
  strength 
  was 
  

   added 
  to 
  a 
  definite 
  amount 
  of 
  distilled 
  water 
  in 
  the 
  containing 
  

   vessel, 
  and 
  the 
  whole 
  mixed 
  thoroughly. 
  By 
  addition 
  of 
  

   more 
  water 
  or 
  solution 
  a 
  second 
  concentration 
  was 
  obtained. 
  

   The 
  conductivity 
  of 
  each 
  solution 
  was 
  determined 
  immediately 
  

   after 
  the 
  measurements 
  of 
  the 
  potential. 
  The 
  experiments 
  

   with 
  each 
  concentration 
  lasted 
  from 
  one 
  to 
  one 
  and 
  a 
  half 
  

   hours. 
  The 
  capillary 
  tube 
  was 
  cleaned 
  with 
  chromic 
  acid 
  

   mixture 
  before 
  each 
  change 
  of 
  solution, 
  and 
  it 
  was 
  assumed 
  

   that 
  durino- 
  the 
  time 
  of 
  measurement 
  the 
  time 
  effect 
  was 
  no 
  

   greater 
  than 
  that 
  previously 
  observed. 
  

  

  If 
  the 
  conductivities 
  are 
  compared 
  with 
  those 
  derived 
  from 
  

   the 
  ionic 
  mobilities 
  of 
  the 
  solutions 
  at 
  these 
  concentrations, 
  it 
  

   will 
  be 
  seen 
  that 
  differences 
  exist. 
  These 
  are 
  due 
  to 
  the 
  fact 
  

   that 
  the 
  distilled 
  water 
  was 
  not 
  of 
  such 
  a 
  high 
  degree 
  of 
  

   purity 
  as 
  that 
  employed 
  in 
  exact 
  conductivity 
  measurements 
  ; 
  

   larger 
  quantities 
  were 
  required 
  than 
  could 
  be 
  obtained 
  con- 
  

   veniently 
  with 
  water 
  of 
  such 
  purity. 
  The 
  errors 
  introduced 
  

   from 
  this 
  source, 
  however, 
  were 
  not 
  large. 
  

  

  Kohlrausch 
  has 
  shown 
  * 
  that 
  the 
  temperature 
  coefficients 
  

   of 
  the 
  conductivity 
  and 
  of 
  friction, 
  for 
  very 
  dilute 
  solutions, 
  

   are 
  very 
  nearly 
  the 
  same, 
  so 
  that 
  as 
  the 
  temperature 
  at 
  which 
  

   the 
  conductivity 
  was 
  measured 
  was 
  always 
  very 
  little 
  dif- 
  

   ferent 
  from 
  that 
  of 
  experiment, 
  the 
  actual 
  conductivity 
  and 
  

   coefficient 
  of 
  friction 
  for 
  that 
  temperature 
  were 
  employed. 
  

   The 
  coefficient 
  of 
  friction 
  was 
  assumed 
  to 
  be 
  the 
  same 
  as 
  that 
  

   for 
  w^aterf, 
  and 
  was 
  calculated 
  from 
  0. 
  E. 
  Meyer's 
  formula 
  J 
  

  

  1-775 
  

   V 
  = 
  

  

  H-0-03315^ 
  + 
  0-0002437<2 
  

  

  * 
  Wied. 
  Ann. 
  vi. 
  p. 
  193 
  (1879). 
  

  

  T 
  This 
  assumption 
  is 
  justifiable, 
  since 
  changes 
  of 
  concentration 
  of 
  

   one-eighth 
  normality 
  with 
  these 
  solutions 
  only 
  produce 
  a 
  difference 
  

   of 
  from 
  0-3-l'7 
  per 
  cent, 
  in 
  the 
  coefficient 
  of 
  friction. 
  

  

  X 
  Wied. 
  Ann. 
  ii. 
  p. 
  394 
  (1877). 
  

  

  