﻿45 
  

  

  of 
  Pressure 
  which 
  accompany 
  Point 
  Discharge. 
  

  

  depends 
  only 
  on 
  the 
  current 
  from 
  the 
  point 
  and 
  the 
  specific 
  

   velocities 
  of 
  the 
  ions, 
  for 
  given 
  geometrical 
  conditions. 
  

  

  Curves 
  VIII. 
  — 
  Negative 
  Peak. 
  

  

  O06 
  % 
  Oxtj. 
  

  

  The 
  greater 
  the 
  wind 
  the 
  more 
  rapidly 
  will 
  the 
  gas 
  be 
  

   cooled 
  by 
  the 
  plate, 
  if, 
  as 
  in 
  our 
  case, 
  the 
  plate 
  is 
  in 
  thermal 
  

   contact 
  with 
  a 
  large 
  mass 
  of 
  metal 
  ; 
  and 
  this 
  will 
  mean 
  that 
  

   the 
  temporary 
  expansion 
  during 
  discharge 
  will 
  be 
  less, 
  other 
  

   things 
  equal. 
  It 
  follows 
  that 
  changes 
  in 
  the 
  amount 
  of 
  this 
  

   expansion 
  per 
  watt 
  will 
  indicate 
  changes 
  in 
  the 
  specific 
  

   velocities, 
  and 
  therefore 
  in 
  the 
  sizes 
  of 
  the 
  ions, 
  if 
  the 
  ex- 
  

   pansion 
  is 
  dependent 
  only 
  on 
  the 
  temperature 
  of 
  the 
  gas 
  ; 
  large 
  

   expansions 
  implying 
  small 
  ions 
  and 
  vice 
  versa. 
  

  

  Of 
  course 
  the 
  expansion 
  is 
  not 
  a 
  certain 
  guide 
  to 
  ionic 
  

   dimensions 
  as 
  heat 
  may 
  not 
  be 
  its 
  only 
  cause 
  ; 
  and 
  the 
  fact 
  

   that 
  in 
  pure 
  hydrogen 
  with 
  a 
  clean 
  point 
  the 
  expansion 
  per 
  

   watt 
  is 
  more 
  than 
  100 
  per 
  cent, 
  greater 
  for 
  negative 
  than 
  for 
  

   positive 
  discharge, 
  seems 
  to 
  show 
  that 
  the 
  smaller 
  size 
  of 
  the 
  

   negative 
  ions 
  is 
  not 
  responsible 
  for 
  the 
  whole 
  of 
  the 
  difference 
  

   between 
  the 
  expansions 
  for 
  positive 
  and 
  negative. 
  

  

  In 
  Table 
  7 
  are 
  given 
  numbers 
  which 
  are 
  proportional 
  to 
  

   the 
  expansions 
  per 
  watt 
  during 
  discharge 
  in 
  the 
  first 
  set 
  of 
  

   oxygen 
  observations 
  ; 
  h 
  being 
  the 
  difference 
  between 
  the 
  

  

  