﻿Conductivity 
  imparted 
  to 
  Liquid 
  Air 
  by 
  Alpha 
  Rays. 
  879 
  

  

  experiments 
  show 
  that 
  of 
  the 
  three 
  alcohols, 
  the 
  amyl 
  was 
  

   the 
  best 
  insulator 
  and 
  the 
  methyl 
  the 
  poorest. 
  The 
  experi- 
  

   ments 
  also 
  show 
  that 
  the 
  liquid 
  air 
  was 
  a 
  very 
  much 
  better 
  

   insulator 
  than 
  any 
  of 
  the 
  three 
  alcohols. 
  

  

  In 
  another 
  set 
  of 
  experiments 
  a 
  small 
  air-condenser 
  of 
  

   about 
  100 
  e.s.u. 
  enpacity 
  was 
  made 
  up 
  of 
  brass 
  plates 
  and 
  

   inserted 
  in 
  a 
  brass 
  box, 
  the 
  latter 
  being 
  placed 
  in 
  a 
  second 
  

   box 
  resting 
  on 
  and 
  surrounded 
  with 
  wool. 
  This 
  condenser 
  

   was 
  charged 
  to 
  a 
  potential 
  of 
  894 
  volts 
  with 
  a 
  battery 
  of 
  

   small 
  storage-cells. 
  When 
  air 
  at 
  atmospheric 
  pressure, 
  

   carefully 
  filtered 
  liquid 
  air, 
  and 
  xylene 
  were 
  in 
  turn 
  used 
  as 
  

   the 
  dielectric, 
  and 
  the 
  potential 
  difference 
  mentioned 
  applied 
  

   to 
  the 
  condenser, 
  the 
  charge 
  obtained 
  in 
  each 
  case 
  was 
  

   ascertained 
  by 
  discharging 
  the 
  condenser 
  through 
  a 
  sensitive 
  

   ballistic 
  galvanometer 
  with 
  a 
  specially 
  constructed 
  key 
  

   supported 
  upon 
  a 
  paraffin 
  block. 
  

  

  The 
  deflexions 
  obtained 
  in 
  a 
  series 
  of 
  measurements 
  with 
  

   the 
  three 
  dielectrics 
  are 
  given 
  in 
  Table 
  I. 
  

  

  Table 
  T. 
  

  

  

  Deflexions 
  

  

  on 
  scale 
  of 
  galvanometer 
  with 
  

  

  

  

  iifferent 
  dielectrics 
  

  

  

  Charging 
  

   potential. 
  

  

  

  

  

  

  

  

  

  Air 
  at 
  atmo- 
  

  

  Liquid 
  

   air. 
  

  

  Xylene. 
  

  

  

  spheric 
  pressure. 
  

  

  894 
  volts. 
  

  

  11*75 
  mm. 
  

  

  16*5 
  mm. 
  

  

  21-9 
  mm. 
  

  

  

  11-75 
  

  

  170 
  

  

  222 
  

  

  

  11-4 
  

  

  1(5-75 
  

  

  23-0 
  

  

  

  12-0 
  

  

  168 
  

  

  23-0 
  

  

  

  1T6 
  

  

  167 
  

  

  24-0 
  

  

  

  120 
  

  

  16 
  5 
  

  

  21-0 
  

  

  

  11-50 
  

  

  16 
  5 
  

  

  23 
  5 
  

  

  

  

  16-4 
  

  

  22-5 
  

  

  

  

  16-7 
  

  

  233 
  

  

  

  

  16-4 
  

  

  24-2 
  

  

  

  Means 
  11*71 
  

  

  166 
  

  

  22-86 
  

  

  These 
  numbers, 
  it 
  will 
  be 
  seen, 
  if 
  we 
  take 
  the 
  dielectric 
  

   constants 
  of 
  air 
  at 
  atmospheric 
  pressure 
  to 
  be 
  unity, 
  give 
  

   1*95 
  and 
  1*42 
  as 
  the 
  dielectric 
  constants 
  for 
  xylene 
  and 
  liquid 
  

   air 
  respectively. 
  The 
  value 
  obtained 
  for 
  liquid 
  air 
  is, 
  there- 
  

   fore, 
  about 
  50 
  per 
  cent, 
  lower 
  than 
  that 
  given 
  by 
  Fleming 
  

   and 
  Dewar. 
  

  

  