﻿5SS 
  Messrs. 
  Cameron 
  and 
  Oettinger 
  on 
  Electromotive 
  

  

  glass 
  tubes 
  connected 
  by 
  a 
  diaphragm 
  o£ 
  burnt 
  clay 
  and 
  

   similar 
  substances. 
  Zollner 
  * 
  showed 
  that 
  what 
  held 
  for 
  a 
  

   bundle 
  of 
  capillaries 
  applied 
  with 
  equal 
  force 
  to 
  a 
  single 
  

   tube, 
  while 
  further 
  experimental 
  work 
  was 
  carried 
  out 
  by 
  

   Edlundf, 
  HagaJ, 
  Clark 
  §, 
  Dorn 
  ||, 
  and 
  Saxeni". 
  Their 
  

   results 
  are 
  in 
  general 
  agreement 
  with 
  each 
  other, 
  and, 
  

   especially 
  those 
  of 
  Dorn, 
  entirely 
  agree 
  with 
  the 
  Helmholtz 
  

   theory. 
  

  

  All 
  these 
  experimental 
  investigations 
  consider 
  the 
  factor 
  

  

  0i 
  — 
  (^a, 
  or 
  its 
  expanded 
  form 
  //, 
  (Lamb's 
  {(j>i—<j)a) 
  -.), 
  as 
  a 
  

  

  constant. 
  Whether 
  this 
  is 
  the 
  case 
  or 
  not 
  has 
  remained 
  

   unverified, 
  since 
  independent 
  determination 
  of 
  this 
  value 
  is 
  

   not 
  possible. 
  The 
  figure 
  calculated 
  by 
  Helmholtz 
  and 
  Dorn 
  

   is 
  about 
  4 
  daniell 
  (5'1 
  volts 
  when 
  corrected 
  for 
  modern 
  

   units), 
  which 
  seems 
  a 
  rather 
  large 
  value 
  for 
  the 
  potential 
  

   between 
  glass 
  and 
  water, 
  considering 
  the 
  fact 
  that 
  much 
  

   smaller 
  potentials, 
  so 
  far 
  as 
  we 
  are 
  aware, 
  always 
  produce 
  

   development 
  of 
  hydrogen 
  gas**. 
  Much 
  smaller 
  values, 
  

   strikingly 
  altering 
  with 
  the 
  concentration 
  of 
  the 
  solution, 
  

   have 
  been 
  derived 
  from 
  the 
  electric 
  endosmose 
  experiments 
  

   of 
  Wiedemann 
  tt^ 
  Quincke 
  J 
  J, 
  and 
  Freund 
  §§, 
  so 
  that 
  one 
  

   point 
  of 
  the 
  theory 
  still 
  remains 
  unsettled. 
  

  

  A 
  way 
  of 
  access 
  to 
  the 
  potential 
  diff'erence 
  between 
  glass 
  

   and 
  solutions 
  has 
  been 
  opened 
  recently 
  by 
  Haber 
  and 
  Kle- 
  

   mensiewicz 
  |||1, 
  who 
  have 
  been 
  able 
  to 
  prove 
  that 
  the 
  surface 
  

   of 
  ordinary 
  glass 
  acts 
  perfectly 
  as 
  a 
  so-called 
  hydrogen 
  

   electrode 
  of 
  constant 
  hydrogen 
  pressure. 
  The 
  change 
  of 
  

   potential 
  produced 
  with 
  such 
  an 
  electrode 
  by 
  altering 
  the 
  

   acidity 
  or 
  alkalinity 
  of 
  the 
  surrounding 
  solution 
  is 
  well 
  

   known. 
  The 
  difference 
  of 
  potential 
  between 
  two 
  such 
  elec- 
  

   trodes, 
  one 
  dipping 
  into 
  acid 
  the 
  other 
  into 
  alkali, 
  was 
  made 
  

  

  * 
  Pogg. 
  An7i. 
  cxlviii. 
  p. 
  640 
  (1873). 
  

  

  t 
  Wied. 
  An7i. 
  i. 
  p. 
  161 
  (1877) 
  ; 
  ix. 
  p. 
  95 
  (1880\ 
  

  

  X 
  Ibid. 
  ii. 
  p. 
  326 
  (1877). 
  

  

  § 
  i^edii. 
  p. 
  336(1877). 
  

  

  II 
  Ibid. 
  V. 
  p. 
  20 
  (1878) 
  ; 
  ix. 
  p. 
  513 
  (1880) 
  ; 
  x. 
  p. 
  71 
  (1880). 
  

  

  H 
  Ibid, 
  xlvii. 
  p. 
  46 
  (1892). 
  

  

  ** 
  See 
  table 
  of 
  absolute 
  potentials 
  by 
  Wilsmore 
  and 
  Ostwald, 
  

   Zeitschr.f. 
  phys. 
  Chemie, 
  xxxvi. 
  p. 
  92 
  (1901). 
  Billiter's 
  absolute 
  zero 
  point 
  

   (Drude's 
  Ann. 
  xi. 
  p. 
  137, 
  1903), 
  althoug-h 
  different, 
  is 
  still 
  near 
  enough 
  

   to 
  Ostwald's 
  for 
  the 
  validity 
  of 
  the 
  above 
  consideration. 
  

  

  ft 
  Pogg. 
  Ann. 
  Ixxxvii. 
  p. 
  321 
  (1852). 
  

  

  XX 
  Ibid, 
  cxiii. 
  p. 
  513 
  (1861). 
  

  

  §§ 
  Wied. 
  Ann. 
  vii. 
  p. 
  44 
  (1879). 
  

  

  nil 
  Zeitschr.f. 
  phys. 
  Chem. 
  1909. 
  

  

  