﻿590 
  Messrs. 
  Cameron 
  and 
  Oettinger 
  on 
  Electromotive 
  

  

  (metal, 
  salt 
  solution, 
  as 
  well 
  as 
  other 
  two-phase 
  systems) 
  has 
  

   for 
  twenty 
  years 
  formed 
  the 
  subject 
  o£ 
  unsettled 
  dispute, 
  even 
  

   such 
  a 
  qualitative 
  result 
  did 
  not 
  seem 
  to 
  lack 
  importance. 
  

   Moreover, 
  the 
  electromotive 
  £oi-ce 
  at 
  the 
  boundary 
  o£ 
  two 
  

   phase 
  systems 
  such 
  as 
  glass 
  and 
  liquid 
  is 
  of 
  special 
  interest, 
  

   since 
  Haber 
  has 
  shown 
  that 
  the 
  law^s 
  governing 
  this 
  electro- 
  

   motive 
  force 
  are 
  applicable 
  to 
  interesting 
  electro-physiological 
  

   phenomena. 
  

  

  This 
  paper 
  contains 
  an 
  account 
  of 
  attempts 
  to 
  verify 
  the 
  

   theory 
  from 
  this 
  point 
  of 
  view, 
  and 
  though 
  our 
  results 
  give 
  

   only 
  a 
  qualitative 
  confirmation, 
  for 
  the 
  reasons 
  just 
  stated, 
  

   it 
  seems 
  desirable 
  to 
  publish 
  them, 
  especially 
  since 
  considerable 
  

   time 
  maj^ 
  elapse 
  before 
  the 
  experimental 
  difficulties 
  are 
  

   sufficiently 
  overcome 
  to 
  permit 
  of 
  completer 
  verification. 
  

  

  Experimental 
  Part 
  : 
  Apparatus. 
  

  

  The 
  apparatus 
  differs 
  in 
  a 
  number 
  of 
  essentials 
  from 
  those 
  

   emploj^ed 
  by 
  previous 
  investigators, 
  and 
  as 
  it 
  seems 
  easier 
  to 
  

   construct 
  and 
  to 
  use 
  than 
  these, 
  it 
  may 
  be 
  described 
  shortly. 
  

   It 
  consists 
  essentially 
  of 
  four 
  parts, 
  an 
  instrument 
  for 
  

   measuring 
  potentials, 
  a 
  capillary 
  tube 
  containing 
  electrodes, 
  

   a 
  stout 
  glass 
  vessel 
  to 
  which 
  it 
  is 
  joined, 
  containing 
  the 
  liquid 
  

   under 
  examination, 
  and 
  an 
  apparatus 
  for 
  maintaining 
  constant 
  

   pressure. 
  The 
  apparatus 
  was 
  tested 
  by 
  repeating 
  the 
  ex- 
  

   periments 
  of 
  Dorn 
  wdth 
  pure 
  water; 
  in 
  this 
  way 
  a 
  number 
  

   of 
  errors 
  in 
  it 
  were 
  detected 
  which 
  require 
  to 
  be 
  avoided, 
  and 
  

   may 
  therefore 
  be 
  mentioned. 
  

  

  In 
  all 
  cases 
  a 
  quadrant 
  electrometer 
  was 
  used 
  to 
  measure 
  

   the 
  potential 
  difference 
  ; 
  in 
  this 
  w^ay 
  errors 
  arising 
  from 
  

   polarization, 
  which 
  occur 
  with 
  galvanometers 
  or 
  with 
  electro- 
  

   meters 
  of 
  greater 
  capacity, 
  were 
  avoided. 
  Both 
  the 
  Thomson 
  

   instrument 
  with 
  bifilar 
  suspension 
  and 
  that 
  with 
  a 
  platinum 
  

   hair-suspension 
  and 
  Dolezalek 
  needle, 
  were 
  employed 
  at 
  

   different 
  times. 
  The 
  capillaries 
  used 
  were 
  calibrated 
  with 
  a 
  

   shifting 
  thread 
  of 
  mercury, 
  and 
  selected 
  so 
  that 
  the 
  variation 
  

   in 
  diameter 
  was 
  slight. 
  Different 
  forms 
  of 
  electrodes 
  were 
  

   tested. 
  At 
  first 
  side 
  tubes 
  w^ere 
  blown 
  on 
  to 
  the 
  capillary, 
  

   and 
  completely 
  filled 
  with 
  mercury, 
  so 
  that 
  the 
  mercury 
  was 
  

   in 
  contact 
  with 
  the 
  stream 
  of 
  liquid; 
  contact 
  w^as 
  allowed 
  

   with 
  the 
  electrometer 
  by 
  platinum 
  wires 
  sealed 
  through 
  the 
  

   ends 
  of 
  the 
  side 
  tubes. 
  The 
  potentials 
  derived 
  from 
  these 
  

   electrodes 
  were 
  not 
  proportional 
  to 
  the 
  fall 
  of 
  pressure 
  

   between 
  them, 
  i. 
  e. 
  did 
  not 
  agree 
  with 
  the 
  Helmholtz 
  formula; 
  

   on 
  using 
  the 
  same 
  tubes 
  without 
  mercury 
  worse 
  results 
  were 
  

  

  