﻿Effects 
  at 
  the 
  Cathode 
  in 
  Vacuum 
  Tubes. 
  

  

  417 
  

  

  of 
  the 
  positive 
  carriers, 
  and 
  there 
  the 
  electric 
  field 
  is 
  very- 
  

   weak, 
  and 
  hence 
  in 
  the 
  negative 
  glow 
  little 
  energy 
  can 
  be 
  

   acquired. 
  So 
  that 
  the 
  maximum 
  energy 
  a 
  positive 
  carrier 
  

   •can 
  give 
  up 
  to 
  the 
  cathode 
  is 
  that 
  obtained 
  by 
  its 
  passing 
  

   through 
  the 
  normal 
  cathode 
  fall. 
  For 
  this 
  reason 
  V 
  was 
  

   taken 
  as 
  the 
  normal 
  cathode 
  fall. 
  

  

  § 
  6. 
  Preparation 
  of 
  Gases, 
  

  

  Experiments 
  were 
  performed 
  in 
  air, 
  oxygen, 
  hydrogen, 
  

   and 
  nitrogen. 
  

  

  The 
  oxygen 
  was 
  prepared 
  from 
  pure 
  potassium 
  perman- 
  

   ganate 
  crystals. 
  These 
  were 
  placed 
  in 
  a 
  glass 
  tube 
  sealed 
  

   -on 
  to 
  the 
  vacuum-tube. 
  The 
  whole 
  was 
  pumped 
  out 
  empty, 
  

   and 
  frequently 
  washed 
  out 
  with 
  gas 
  before 
  use. 
  

  

  Hydrogen* 
  was 
  obtained 
  by 
  the 
  electrolysis 
  of 
  water 
  and 
  

   purified 
  in 
  the 
  following 
  way. 
  The 
  hydrogen 
  was 
  prepared 
  

   in 
  the 
  tube 
  C 
  (fig. 
  3) 
  and 
  admitted 
  through 
  a 
  tap 
  to 
  the 
  

   vessel 
  A, 
  previously 
  evacuated 
  by 
  means 
  of 
  an 
  aspirator. 
  

   In 
  this 
  vessel 
  was 
  a 
  palladium 
  wire 
  B 
  sealed 
  through 
  the 
  

   end 
  of 
  a 
  tube 
  D 
  which 
  was 
  connected 
  to 
  the 
  vacuum-tube, 
  

  

  * 
  This 
  method 
  was 
  seen 
  in 
  use 
  in 
  the 
  Physical 
  Institute 
  of 
  the 
  

   University 
  of 
  Gottingen. 
  

  

  