﻿Volta 
  Electricity 
  of 
  Metals. 
  421 
  

  

  experiment, 
  obtaining 
  the 
  same 
  result 
  as 
  lie 
  had 
  obtained. 
  

   This 
  shows 
  that 
  the 
  result 
  given 
  above 
  was 
  not 
  likely 
  to 
  be 
  

   due 
  to 
  an 
  impurity 
  which 
  had 
  influenced 
  the 
  action 
  of 
  the 
  

   oxygen. 
  

  

  § 
  58. 
  Without 
  any 
  further 
  treatment 
  the 
  same 
  copperplate 
  

   was 
  placed 
  in 
  the 
  bell-jar 
  and 
  the 
  oxygen 
  admitted. 
  After 
  

   forty-five 
  minutes 
  it 
  was 
  taken 
  out 
  and 
  its 
  potential 
  again 
  

   measured 
  by 
  comparison 
  with 
  the 
  other 
  plate. 
  The 
  results 
  

   are 
  given 
  in 
  the 
  following 
  table, 
  time 
  being 
  counted 
  from 
  the 
  

   moment 
  the 
  plate 
  was 
  taken 
  out 
  of 
  the 
  oxygen 
  : 
  — 
  

  

  Time, 
  

   li. 
  m. 
  

   2 
  

  

  Contact-potential 
  

   v. 
  

  

  •13 
  

  

  10 
  

  

  •08 
  

  

  21 
  

  

  •07 
  

  

  29 
  

  

  •06 
  

  

  The 
  experiment 
  was 
  discontinued 
  before 
  the 
  plate 
  had 
  

   returned 
  to 
  its 
  original 
  value 
  ; 
  but 
  it 
  would 
  no 
  doubt 
  have 
  

   done 
  so 
  in 
  a 
  few 
  hours, 
  for 
  the 
  amount 
  of 
  change, 
  and 
  its 
  

   rate, 
  are 
  almost 
  exactly 
  the 
  same 
  as 
  in 
  the 
  former 
  experiment 
  

   (see 
  § 
  56). 
  

  

  § 
  59. 
  In 
  the 
  following 
  experiment 
  the 
  conditions 
  were 
  

   somewhat 
  varied. 
  A 
  copper 
  plate 
  was 
  polished 
  on 
  glass- 
  

   paper. 
  It 
  gave, 
  with 
  a 
  standard 
  copper 
  plate, 
  

  

  -•05 
  v. 
  

  

  A 
  jet 
  of 
  oxygen 
  was 
  now 
  sent 
  against 
  its 
  surface 
  for 
  two 
  or 
  

   three 
  minutes, 
  and 
  with 
  the 
  same 
  standard 
  plate 
  it 
  now 
  gave 
  

  

  -•06 
  v. 
  

  

  It 
  was 
  then 
  left 
  in 
  oxygen 
  for 
  twenty- 
  five 
  minutes, 
  and 
  on 
  

   being 
  taken 
  out 
  gave 
  

  

  Time. 
  Contact-potential, 
  

  

  h. 
  m. 
  v. 
  

  

  4 
  +-060 
  

  

  13 
  + 
  '035 
  

  

  which 
  shows 
  that 
  its 
  immersion 
  had 
  raised 
  its 
  potential 
  "12 
  v 
  

   I 
  now 
  warmed 
  it 
  with 
  a 
  soldering-bolt 
  applied 
  to 
  its 
  back. 
  

   When 
  about 
  47° 
  G. 
  (see 
  Chap. 
  IX.) 
  it 
  gave 
  

  

  Time. 
  Contact-potential, 
  

  

  h. 
  m. 
  v. 
  

  

  16 
  +-020. 
  

  

  