﻿56 
  Mr. 
  R. 
  F. 
  Earhart 
  on 
  the 
  Discharge 
  

  

  Character 
  of 
  the 
  Discharge 
  produced 
  by 
  Potentials 
  less 
  

   than 
  those 
  required 
  to 
  ionize 
  a 
  gas. 
  

  

  In 
  order 
  to 
  determine 
  whether 
  the 
  carriers 
  of 
  the 
  discharge 
  

   through 
  these 
  abnormally 
  small 
  distances 
  are 
  negative 
  cor- 
  

   puscles 
  or 
  positive 
  metal 
  ions 
  or 
  both, 
  I 
  have 
  made 
  a 
  

   modification 
  o£ 
  Dr. 
  Hobbs' 
  s 
  experiment. 
  

  

  It 
  is 
  possible 
  for 
  a 
  discharge 
  to 
  occur 
  between 
  electrodes 
  

   whose 
  potential-difference 
  is 
  less 
  than 
  that 
  required 
  to 
  ionize 
  

   the 
  gas. 
  The 
  distance 
  through 
  which 
  this 
  discharge 
  occurs 
  

   depends 
  on 
  the 
  character 
  of 
  the 
  electrodes. 
  

  

  PI. 
  I. 
  fig. 
  4 
  shows 
  the 
  results 
  obtained 
  by 
  Hobbs 
  for 
  elec- 
  

   trodes 
  of 
  Pt, 
  Ag, 
  and 
  Al. 
  Hobbs 
  also 
  used 
  Bi, 
  Ni, 
  Sb, 
  Zn, 
  

   and 
  Mg. 
  The 
  potential 
  gradients 
  for 
  these 
  elements 
  lie 
  

   within 
  the 
  limits 
  of 
  those 
  for 
  Pt 
  and 
  Al. 
  

  

  In 
  Tables 
  VII. 
  to 
  XV. 
  distances 
  in 
  wave-lengths 
  are 
  given 
  

   in 
  the 
  first 
  column 
  under 
  A. 
  Potential-differences 
  in 
  the 
  

   second 
  column 
  are 
  indicated 
  by 
  V. 
  

  

  Table 
  VII. 
  

  

  Al 
  + 
  Al 
  - 
  

  

  X. 
  

  

  < 
  

  

  X. 
  

   \ 
  

  

  V. 
  

  

  2 
  

  

  121 
  

  

  295 
  

  

  2 
  

  

  159 
  

  

  4 
  

  

  254 
  

  

  2-5 
  

  

  164 
  

  

  4-5 
  

  

  301 
  

  

  2-5 
  

  

  212 
  

  

  5 
  

  

  306 
  

  

  3 
  

  

  197 
  

  

  5 
  

  

  320 
  

  

  3 
  

  

  188 
  

  

  6 
  

  

  329 
  

  

  35 
  

  

  188 
  

  

  6 
  

  

  342 
  

  

  Table 
  VIII. 
  

   Al 
  4- 
  Pt 
  - 
  

  

  X. 
  

  

  V. 
  

  

  x 
  

  

  v 
  

  

  2 
  

  

  103 
  

  

  . 
  

  

  305 
  

  

  2-5 
  

  

  169 
  

  

  4 
  

  

  301 
  

  

  3 
  

  

  258 
  

  

  4'5 
  

  

  304 
  

  

  3 
  

  

  2(58 
  

  

  5 
  

  

  329 
  

  

  3-5 
  

  

  277 
  

  

  5 
  

  

  329 
  

  

  4 
  

  

  805 
  

  

  6 
  

  

  338 
  

  

  4 
  

  

  320 
  

  

  c» 
  

  

  338 
  

  

  