﻿600 
  Messrs. 
  Cameron 
  and 
  Oettinger 
  on 
  Electromotive 
  

  

  In 
  the 
  next 
  table 
  are 
  given 
  the 
  values 
  found 
  for 
  alkaline 
  

   solutions. 
  

  

  Solution. 
  

   NH4OH 
  

  

  Concentration. 
  

  

  A. 
  

  

  B. 
  

  

  0. 
  

  

  Temp. 
  

  

  E,. 
  1 
  E,. 
  

  

  N/5000 
  

  

  410 
  

  

  805 
  

  

  203 
  

  

  398 
  

  

  0-050 
  

  

  17° 
  

  

  +0-018 
  

  

  +0-496 
  

   0-834 
  

  

  

  N/2500 
  

  

  845 
  

  

  418 
  

  

  0-050 
  

  

  170 
  

  

  +0-022 
  

  

  +0-599 
  

  

  

  N/2500 
  

  

  405 
  

  

  200 
  

  

  0-050 
  

  

  17° 
  

  

  +0-027 
  

  

  +0-308 
  

  

  KOH 
  

  

  N/2000 
  

  

  400 
  

  

  760 
  

  

  198 
  

   376 
  

  

  0-033 
  

  

  16° 
  

  

  +0-003 
  

  

  +0-283 
  

   0-489 
  

  

  1 
  

  

  Solution. 
  

  

  .3 
  

  

  E, 
  

  

  l/«. 
  

  

  ExoooK 
  

  

  

  <Pi-(pa. 
  

  

  NH.OH 
  

  

  -0005 
  

  

  +0-485+5 
  «/o 
  

   0-823+3 
  % 
  

  

  0-4302x105 
  

  

  5-55 
  xlC 
  

  

  4-81 
  

  

  -5 
  

  

  5-45+5 
  % 
  

  

  4-72+3 
  % 
  

  

  

  -0-016 
  

  

  +0-596+6 
  > 
  

  

  0-2602 
  

  

  5-48 
  

  

  

  5-37 
  ±6 
  % 
  

  

  

  +0-009 
  

  

  +0-290+6 
  «/o 
  

  

  2654 
  

  

  5-46 
  

  

  

  5-35±6 
  0/0 
  

  

  KOH 
  

  

  -0016 
  

  

  +0-289+6 
  0/0 
  

   0-483+4 
  o/„ 
  

  

  0-2028 
  

  

  7-20 
  

   6-41 
  

  

  

  7-23+6 
  0/0 
  

   6-44+4 
  0,. 
  

  

  

  

  

  

  

  

  -^ 
  ' 
  1 
  

  

  It 
  is 
  at 
  once 
  apparent 
  that 
  these 
  values 
  are 
  all 
  greater 
  than 
  

   4*5 
  volts* 
  ; 
  the 
  mean 
  can 
  be 
  taken 
  perhaps 
  in 
  the 
  neighbourhood 
  

   of 
  5*5 
  volts, 
  so 
  that 
  there 
  is 
  a 
  distinct 
  difference 
  between 
  acid 
  

   and 
  alkali 
  much 
  greater 
  than 
  the 
  error 
  of 
  experiment. 
  In 
  all 
  

   cases 
  the 
  solutions 
  were 
  tested 
  and 
  the 
  acidity 
  and 
  alkalinity 
  

   were 
  just 
  perceptible. 
  

  

  The 
  values 
  obtained 
  for 
  water 
  by 
  Helmholtz 
  from 
  Quincke's 
  

   experiments, 
  and 
  by 
  Dorn, 
  are 
  both 
  given 
  as 
  nearly 
  exactly 
  

   4 
  daniell, 
  which, 
  when 
  corrected 
  to 
  modern 
  units, 
  is 
  equal 
  to 
  

   5*07 
  volts. 
  This 
  value 
  lies 
  between 
  our 
  average 
  values 
  for 
  

   acids 
  and 
  bases. 
  The 
  exact 
  degree 
  of 
  acidity 
  or 
  alkalinity 
  of 
  

   such 
  " 
  pure 
  " 
  water, 
  or 
  of 
  neutral 
  solutions 
  is 
  of 
  course 
  

   uncertain. 
  It 
  is 
  of 
  interest, 
  however, 
  to 
  note 
  that 
  an 
  experi- 
  

   ment 
  which 
  we 
  carried 
  out 
  with 
  a 
  solution 
  of 
  potassium 
  

   chloride 
  also 
  gave 
  intermediate 
  values. 
  

  

  * 
  To 
  try 
  the 
  influence 
  of 
  concentration, 
  an 
  experiment 
  was 
  carried 
  

   out 
  witli 
  N/50 
  ammonia 
  whicli, 
  although 
  the 
  value 
  of 
  E4 
  was 
  so 
  small 
  

   that 
  little 
  stress 
  could 
  be 
  laid 
  on 
  it, 
  at 
  least 
  supports 
  the 
  contention 
  

   xhat 
  the 
  higher 
  value 
  for 
  (pi—cpa 
  is 
  valid. 
  The 
  figures 
  are: 
  — 
  A 
  =920, 
  

   B=455, 
  C 
  = 
  0-060, 
  temp. 
  18° 
  ; 
  E 
  =+0-035, 
  E.,= 
  +0-087, 
  E3 
  = 
  +0-023, 
  

   E, 
  = 
  +0-057+15 
  °/o 
  volt 
  5 
  l/*c 
  = 
  0-02130x10- 
  5; 
  Eiooo'c 
  = 
  5-89x10-5, 
  

  

  