﻿R. 
  S. 
  Dean 
  — 
  Electron 
  Theory 
  of 
  Passivity. 
  125 
  

  

  that 
  is 
  the 
  electron 
  density 
  at 
  the 
  surface 
  is 
  less 
  than 
  that 
  

   of 
  the 
  interior 
  and 
  is 
  given 
  by 
  (6). 
  This 
  of 
  course 
  is 
  only 
  

   true 
  for 
  paramagnetic 
  metals 
  and 
  the 
  more 
  paramagnetic 
  

   the 
  substance 
  the 
  greater 
  the 
  passivity, 
  which 
  at 
  once 
  

   explains 
  the 
  extraordinary 
  tendency 
  to 
  passivation 
  found 
  

   in 
  the 
  iron 
  group. 
  

  

  So 
  far 
  we 
  have 
  considered 
  only 
  a 
  constant 
  magnetic 
  

   field; 
  if 
  we 
  examine 
  equation 
  (2) 
  it 
  will 
  be 
  seen 
  that 
  V 
  is 
  

   inversely 
  proportional 
  to 
  F, 
  hence 
  it 
  is 
  apparent 
  that 
  if 
  a 
  

   magnetic 
  field 
  be 
  applied 
  to 
  a 
  conductor, 
  V 
  will 
  be 
  lowered, 
  

   causing 
  the 
  number 
  of 
  electrons 
  with 
  greater 
  velocities 
  

   than 
  Ve 
  to 
  be 
  smaller 
  and 
  hence 
  the 
  passivity 
  produced 
  

   by 
  any 
  given 
  set 
  of 
  conditions 
  will 
  be 
  less 
  in 
  a 
  magnetic 
  

   field 
  than 
  without 
  or 
  the 
  force 
  necessary 
  to 
  produce 
  a 
  

   given 
  degree 
  of 
  passivity 
  will 
  be 
  proportional 
  to 
  F. 
  

   However 
  if 
  a 
  conductor 
  be 
  once 
  passivated 
  no 
  effect 
  of 
  

   changing 
  the 
  magnetic 
  field 
  should 
  be 
  anticipated. 
  This 
  

   is 
  practically 
  the 
  effect 
  found 
  by 
  Nichols 
  and 
  Franklin 
  3 
  

   and 
  by 
  Byers 
  4 
  and 
  his 
  collaborators. 
  

  

  3 
  Nichols 
  and 
  Franklin, 
  this 
  Journal, 
  (3) 
  31, 
  272, 
  1886; 
  (3) 
  34, 
  419, 
  

   1887. 
  

  

  4 
  Byers 
  and 
  Darrin, 
  Journ. 
  Amer. 
  Chem. 
  Soc, 
  32, 
  550, 
  1910. 
  

  

  4145 
  Maryland 
  Ave., 
  

   St. 
  Louis. 
  Mo. 
  

  

  