﻿572 
  Prof. 
  E. 
  H. 
  Barton 
  and 
  Mr. 
  W. 
  B. 
  Kilby 
  on 
  

  

  ionized 
  either 
  by 
  X-rays, 
  by 
  the 
  radiation 
  from 
  5 
  mg. 
  of 
  

   radium 
  bromide, 
  or 
  by 
  both 
  these 
  agencies 
  together. 
  

  

  Fig. 
  3. 
  — 
  Diagram 
  illustrating 
  Initial 
  Experiments. 
  

  

  J 
  

  

  en 
  

  

  The 
  method 
  was 
  to 
  take 
  readings 
  alternately 
  for 
  the 
  air 
  

   ionized 
  and 
  nn-ionized, 
  the 
  exact 
  positions 
  on 
  the 
  scale 
  

   where 
  the 
  tube 
  just 
  commenced 
  and 
  also 
  just 
  failed 
  to 
  glow 
  

   being 
  in 
  each 
  case 
  observed. 
  

  

  Another 
  plan 
  was 
  to 
  use 
  a 
  leyden-jar 
  as 
  the 
  capacity 
  in 
  

   the 
  primary 
  circuit, 
  and 
  to 
  place 
  a 
  multiple-plate 
  air- 
  

   condenser 
  in 
  parallel 
  with 
  the 
  cylindrical 
  capacity 
  of 
  the 
  

   responding 
  circuit, 
  and 
  to 
  observe 
  the 
  change 
  needed 
  in 
  the 
  

   induction 
  and 
  in 
  the 
  latter 
  capacity 
  to 
  compensate 
  for 
  that 
  

   in 
  the 
  former 
  when 
  the 
  air 
  between 
  the 
  plates 
  was 
  ionized. 
  

   A 
  large 
  number 
  of 
  readings 
  showed 
  that 
  the 
  fractional 
  

   change, 
  if 
  any, 
  in 
  the 
  capacity 
  was 
  very 
  small. 
  Moreover, 
  

   as 
  with 
  the 
  straight 
  wire 
  inductance 
  in 
  use 
  the 
  neon 
  tube 
  

   glowed 
  over 
  a 
  length 
  of 
  at 
  least 
  15 
  cm., 
  it 
  appeared 
  desirable 
  

   to 
  use 
  some 
  still 
  more 
  sensitive 
  device. 
  

  

  Final 
  Arrangement. 
  — 
  The 
  method 
  described 
  below, 
  and 
  

   shown 
  in 
  fig. 
  4, 
  was 
  thereupon 
  devised, 
  and 
  it 
  was 
  along 
  

   these 
  lines 
  that 
  the 
  work 
  proceeded. 
  The 
  primary 
  circuit 
  

   was 
  that 
  of 
  the 
  Fleming 
  cymometer 
  in 
  its 
  original 
  form, 
  

   having 
  a 
  spark-gap 
  G 
  of 
  2 
  mm. 
  at 
  one 
  end 
  and 
  a 
  leyden-jar 
  

   J 
  (quart 
  size) 
  at 
  the 
  other. 
  The 
  circuit 
  had 
  a 
  frequency 
  of 
  

   1*93 
  x 
  10 
  6 
  per 
  second. 
  At 
  a 
  clear 
  distance 
  of 
  10 
  cm. 
  from 
  the 
  

   primary 
  circuit 
  was 
  placed 
  the 
  responding 
  circuit, 
  having 
  a 
  

   straight 
  wire 
  AB 
  of 
  0'5 
  cm. 
  diameter 
  soldered 
  on 
  at 
  one 
  end 
  

   in 
  place 
  of 
  the 
  usual 
  helix. 
  Connected 
  to 
  the 
  terminals 
  of 
  

   the 
  variable 
  cylindrical 
  condenser 
  of 
  the 
  cymometer, 
  and 
  

  

  