﻿Chemistry 
  and 
  Physics. 
  149 
  

  

  3. 
  On 
  the 
  Electrolysis 
  of 
  Water. 
  — 
  The 
  electromotive 
  force 
  

   required 
  for 
  the 
  electrolysis 
  of 
  water 
  was 
  shown 
  by 
  v. 
  Helmholtz 
  

   to 
  depend 
  upon 
  the 
  density 
  of 
  the 
  oxygen 
  and 
  the 
  hydrogen 
  at 
  

   the 
  electrodes, 
  being 
  lower 
  in 
  proportion 
  as 
  this 
  density 
  is 
  smaller; 
  

   so 
  that 
  if 
  all 
  gas 
  be 
  removed 
  from 
  the 
  liquid, 
  its 
  value 
  must 
  be 
  

   zero. 
  From 
  an 
  equation 
  connecting 
  the 
  electromotive 
  force 
  of 
  

   polarization 
  A, 
  for 
  any 
  given 
  pressures 
  of 
  the 
  oxygen 
  and 
  hydro- 
  

   gen 
  p 
  and 
  p 
  h 
  , 
  with 
  the 
  electromotive 
  force 
  when 
  the 
  pressure 
  

   is 
  the 
  pressure 
  of 
  the 
  atmosphere 
  p 
  a 
  , 
  he 
  has 
  determined 
  the 
  

   value,A 
  a 
  tobe 
  1-783 
  volts. 
  Sokoloff 
  has 
  sought 
  to 
  obtain 
  a 
  

   direct 
  proof 
  that 
  water 
  can 
  be 
  decomposed 
  with 
  any 
  electromo- 
  

   tive 
  force 
  however 
  small. 
  For 
  this 
  purpose 
  he 
  used 
  a 
  voltameter 
  

   containing 
  two 
  platinum 
  plates, 
  an 
  insulated 
  platinum 
  point 
  being 
  

   placed 
  near 
  each 
  plate. 
  On 
  passing 
  a 
  current, 
  the 
  electrodes 
  

   became 
  polarized 
  by 
  gas 
  layers 
  of 
  definite 
  density. 
  Since 
  these 
  

   gases 
  are 
  electrically 
  neutral 
  and 
  therefore 
  free, 
  they 
  diffuse 
  

   through 
  the 
  liquid, 
  reach 
  the 
  platinum 
  points, 
  and 
  polarize 
  them 
  

   also. 
  By 
  using 
  a 
  sensitive 
  electrometer, 
  the 
  author 
  has 
  shown 
  

   that 
  any 
  electromotive 
  force, 
  however 
  small, 
  can 
  effect 
  the 
  electro- 
  

   lysis. 
  Moreover, 
  he 
  finds 
  that 
  an 
  electromotive 
  force 
  of 
  one 
  volt 
  

   suffices 
  to 
  produce 
  gas 
  having 
  a 
  measureable 
  pressure. 
  In 
  one 
  

   experiment, 
  which 
  lasted 
  16 
  months, 
  a 
  calomel 
  cell 
  (1*072 
  volt) 
  

   produced 
  gas 
  of 
  2*53 
  mm 
  pressure; 
  and 
  this 
  even 
  seems 
  not 
  to 
  be 
  

   the 
  limiting 
  value, 
  as 
  the 
  pressure 
  continued 
  to 
  increase. 
  Similar 
  

   difficulties 
  were 
  met 
  with 
  here 
  to 
  those 
  encountered 
  in 
  ordinary 
  

   electrolysis. 
  Forces 
  are 
  active 
  on 
  the 
  surfaces 
  of 
  the 
  electrodes 
  

   which 
  hinder 
  the 
  free 
  diffusion 
  of 
  the 
  gases 
  and 
  bring 
  about 
  the 
  

   absorption 
  of 
  these 
  gases 
  by 
  the 
  platinum 
  and 
  other 
  metals. 
  

   Hence 
  the 
  accurate 
  determination 
  of 
  A 
  a 
  is 
  not 
  easy. 
  Measure- 
  

   ments 
  at 
  low 
  pressures 
  gave 
  the 
  author 
  a 
  value 
  of 
  0*745 
  volt 
  for 
  

   A 
  a 
  ; 
  a 
  value 
  much 
  smaller 
  than 
  that 
  given 
  by 
  v. 
  Helmholtz. 
  — 
  

  

  Wied. 
  Ann., 
  II, 
  lviii, 
  209-248, 
  June, 
  1896. 
  G. 
  f. 
  b. 
  

  

  4. 
  On 
  the 
  Electrolytic 
  Production 
  of 
  Hypochlorites 
  and 
  Chlo- 
  

   rates. 
  — 
  The 
  electrolysis 
  of 
  solutions 
  of 
  potassium 
  chloride 
  has 
  

   been 
  investigated 
  by 
  Oettel. 
  The 
  current 
  from 
  four 
  storage 
  

   cells 
  was 
  passed 
  through 
  (1) 
  a 
  copper 
  voltameter 
  for 
  measuring 
  

   its 
  strength, 
  (2) 
  an 
  electrolytic 
  gas 
  voltameter, 
  (3) 
  the 
  cells 
  for 
  

   the 
  experiments, 
  (4) 
  an 
  ampere 
  meter, 
  and 
  (5) 
  a 
  resistance 
  box. 
  

   The 
  electrodes 
  of 
  the 
  gas 
  voltameter 
  were 
  of 
  nickel 
  rolled 
  into 
  

   two 
  concentric 
  cylinders, 
  and 
  immersed 
  in 
  solution 
  of 
  caustic 
  

   soda. 
  The 
  experiment 
  cell 
  had 
  a 
  capacity 
  of 
  about 
  115 
  cc 
  and 
  was 
  

   closed 
  tight 
  by 
  means 
  of 
  a 
  rubber 
  cover. 
  Through 
  this 
  cover 
  

   passed 
  the 
  wires 
  to 
  the 
  electrodes, 
  both 
  being 
  of 
  platinum, 
  a 
  

   capillary 
  delivery 
  tube 
  and 
  another 
  glass 
  tube 
  reaching 
  to 
  the 
  

   bottom 
  of 
  the 
  cell, 
  by 
  means 
  of 
  which 
  it 
  could 
  be 
  filled 
  or 
  

   emptied. 
  The 
  current 
  strength 
  employed 
  was 
  from 
  1 
  to 
  1*2 
  

   ampere, 
  and 
  it 
  was 
  continued 
  for 
  two 
  hours. 
  Using 
  neutral 
  

   solutions, 
  the 
  author 
  finds 
  that 
  the 
  main 
  product 
  is 
  hypochlorite, 
  

   83 
  per 
  cent 
  of 
  the 
  active 
  chlorine 
  existing 
  in 
  this 
  form 
  at 
  the 
  end 
  

   of 
  the 
  experiment, 
  and 
  17 
  per 
  cent 
  as 
  chlorate. 
  Addition 
  of 
  

  

  