﻿474 
  

  

  Mr. 
  L. 
  Yeo-arcl 
  on 
  the 
  Electric 
  Discharqe 
  

  

  gradient 
  for 
  each 
  pressure 
  is 
  a 
  function 
  of 
  current. 
  These 
  

   relations 
  are 
  represented 
  in 
  figs. 
  6 
  and 
  7, 
  and 
  show 
  that 
  

   except 
  for 
  very 
  small 
  currents 
  the 
  variation 
  of 
  P.G. 
  obeys 
  

   Herz's 
  law, 
  and 
  especially 
  in 
  such 
  a 
  way 
  that 
  the 
  P.G. 
  

   is 
  very 
  nearly 
  independent 
  of 
  current. 
  

  

  The 
  relation 
  between 
  P.G. 
  and 
  pressure 
  for 
  currents 
  of 
  

   about 
  0*8 
  . 
  10"^ 
  am. 
  is 
  given 
  in 
  fig. 
  8. 
  For 
  pressures 
  less 
  than 
  

   0*3 
  mm. 
  there 
  is 
  a 
  peculiar 
  difference 
  between 
  the 
  curves 
  for 
  

   HOI 
  and 
  HBr. 
  The 
  P.G. 
  for 
  HBr 
  falls 
  rapidly 
  with 
  

   diminution 
  of 
  pressure 
  while 
  for 
  HCl 
  it 
  keeps 
  nearly 
  constant. 
  

   We 
  see 
  that 
  at 
  least 
  for 
  pressures 
  above 
  0*25 
  mm. 
  the 
  

   potential 
  gradients 
  of 
  HCl, 
  HBr, 
  and 
  HI 
  follow 
  in 
  the 
  same 
  

   order 
  as 
  the 
  molecular 
  weights 
  of 
  the 
  gases, 
  when 
  compared 
  

   for 
  equal 
  pressures. 
  The 
  value 
  of 
  the 
  P.G. 
  for 
  oxygen 
  is 
  

   between 
  that 
  of 
  HCl 
  and 
  HBr 
  and 
  nearest 
  to 
  the 
  latter. 
  

  

  Table 
  V. 
  gives 
  the 
  P.G. 
  for 
  the 
  four 
  gases 
  for 
  a 
  series 
  of 
  

   pressures 
  . 
  

  

  Table 
  V— 
  lO-^I 
  = 
  ca. 
  0-8. 
  

  

  p- 
  

  

  HCl. 
  

  

  HBr. 
  

  

  HI. 
  

  

  O2. 
  

  

  1 
  

  

  mm. 
  

   0-4 
  

  

  Tolt/cm. 
  

   36 
  

  

  volt/ciu. 
  

   413 
  

  

  Tolt/cm. 
  

   70 
  

  

  Toit'cm. 
  

   41 
  1 
  

  

  07 
  

  

  41 
  

  

  57 
  

  

  98 
  

  

  53 
  

  

  10 
  

  

  f.l 
  

  

  C8 
  

  

  ISO 
  

  

  64 
  1 
  

  

  1-4 
  

  

  67 
  

  

  86 
  

  

  182 
  

  

  82 
  

  

  1-8 
  

  

  85 
  

  

  106 
  

  

  ... 
  

  

  

  2"2 
  

  

  104 
  

  

  127 
  

  

  

  i 
  

  

  ... 
  j 
  

  

  The 
  results 
  got 
  with 
  respect 
  to 
  the 
  potential 
  gradients 
  for 
  

   HCl, 
  HBr, 
  and 
  HI 
  as 
  far 
  as 
  the 
  I 
  compound 
  is 
  concerned 
  

   is 
  contrary 
  to 
  those 
  found 
  by 
  Matthies 
  for 
  the 
  similarly 
  con- 
  

   stituted 
  gases. 
  Further 
  measurements 
  with 
  the 
  halogen 
  

   elements 
  and 
  their 
  mercury 
  compounds 
  would 
  be 
  desirable 
  to 
  

   find 
  the 
  cause 
  of 
  this 
  discrepancy. 
  In 
  these 
  experiments 
  

   special 
  attention 
  ought 
  to 
  be 
  paid 
  to 
  the 
  structure 
  of 
  the 
  

   discharge, 
  for 
  the 
  possibility 
  is 
  not 
  excluded 
  that 
  the 
  small 
  

   P.G.^'s 
  for 
  the 
  iodine 
  compounds 
  may 
  be 
  due 
  to 
  a 
  striated 
  

   structure, 
  and 
  the 
  fact 
  that 
  the 
  tube 
  had 
  to 
  be 
  surrounded 
  

   with 
  an 
  electrical 
  oven 
  may 
  have 
  made 
  an 
  examination 
  of 
  the 
  

   discharge 
  difficult. 
  

  

  If 
  the 
  values 
  found 
  by 
  Matthies 
  really 
  correspond 
  to 
  a 
  

   uniform 
  structure 
  it 
  seems 
  natural 
  to 
  seek 
  the 
  cause 
  for 
  the 
  

   small 
  P.G. 
  in 
  the 
  case 
  of 
  the 
  iodine 
  compounds 
  in 
  some 
  kind 
  

  

  