﻿862 
  Mr. 
  F. 
  Soddy 
  on 
  the 
  

  

  9 
  hours 
  later, 
  showed 
  a 
  diminution 
  in 
  the 
  interval 
  in 
  the 
  

   ratio 
  of 
  4 
  to 
  3. 
  The 
  7-rays 
  of 
  the 
  preparation, 
  measured 
  

   in 
  the 
  usual 
  way 
  in 
  a 
  lead 
  electroscope 
  at 
  the 
  same 
  times, 
  

   showed 
  no 
  perceptible 
  variation. 
  It 
  was 
  later 
  found 
  thsjt 
  

   the 
  value 
  of 
  the 
  leak 
  due 
  to 
  the 
  difficultly 
  deviable 
  radiation 
  

   varied 
  in 
  a 
  completely 
  unaccountable 
  way. 
  The 
  variation 
  is 
  

   far 
  more 
  marked 
  in 
  air 
  than 
  in 
  hydrogen. 
  The 
  behaviour 
  

   suggested 
  strongly 
  in 
  certain 
  cases 
  that 
  the 
  preparation 
  was 
  

   giving 
  off 
  a 
  radioactive 
  emanation, 
  and 
  from 
  the 
  manner 
  of 
  

   its 
  preparation 
  thorium 
  was 
  suspected. 
  But 
  this 
  was 
  

   completely 
  disproved 
  by 
  special 
  experiments. 
  But 
  the 
  most 
  

   striking 
  proof 
  that 
  the 
  behaviour 
  was 
  not 
  in 
  any 
  way 
  due 
  to 
  

   this 
  cause 
  or 
  to 
  defects 
  in 
  the 
  method 
  of 
  measurement 
  is 
  

   that 
  the 
  ^-radiation 
  as 
  measured 
  by 
  the 
  difference 
  between, 
  

   the 
  leaks 
  with 
  the 
  preparation 
  covered 
  and 
  uncovered 
  

   remained 
  from 
  the 
  start 
  perfectly 
  constant. 
  This 
  shows 
  that 
  

   all 
  the 
  numerous 
  errors 
  to 
  be 
  guarded 
  against 
  in 
  experiments 
  

   where 
  the 
  gas 
  in 
  the 
  instrument 
  is 
  changed 
  have 
  been 
  

   avoided. 
  

  

  A 
  good 
  many 
  rapidly 
  improvised 
  experiments, 
  done 
  with 
  

   the 
  first 
  batch 
  of 
  preparations 
  before 
  their 
  activity 
  decayed, 
  

   had 
  indicated 
  that 
  the 
  difficultly 
  deviable 
  radiation 
  was 
  

   entirely 
  similar 
  in 
  general 
  character, 
  both 
  in 
  the 
  direction 
  

   of 
  their 
  deviation 
  and 
  in 
  the 
  value 
  of 
  their 
  absorption 
  

   coefficient, 
  to 
  the 
  ordinary 
  jS-rajs. 
  The 
  absorption 
  coefficient 
  

   for 
  aluminium, 
  determined 
  by 
  placing 
  strips 
  of 
  foil 
  directly 
  

   over 
  the 
  preparation, 
  placed 
  in 
  the 
  magnetic 
  field, 
  had 
  been 
  

   found 
  to 
  be 
  about 
  24 
  (cm.)~^. 
  Tliis 
  is 
  much 
  less 
  ihan 
  the 
  

   usual 
  value 
  (14), 
  given 
  for 
  the 
  ordinary 
  y8-rays, 
  and 
  is 
  about 
  

   equal 
  to 
  the 
  value 
  after 
  2*5 
  mm. 
  of 
  aluminium 
  have 
  been 
  

   traversed. 
  The 
  field 
  would 
  cause 
  the 
  trajectories 
  of 
  the 
  rays 
  

   in 
  the 
  metal 
  to 
  be 
  lengthened^ 
  but 
  owing 
  to 
  the 
  complete 
  

   scattering 
  suffered 
  by 
  these 
  rays 
  by 
  even 
  thin 
  films 
  of 
  metal, 
  

   it 
  is 
  difficult 
  to 
  state 
  precisely 
  what 
  the 
  effect 
  of 
  the 
  field 
  on 
  

   the 
  absorption 
  coefficient 
  would 
  be. 
  If 
  these 
  rays 
  are 
  really 
  

   yS-rays, 
  the 
  value 
  of 
  Up 
  shows 
  that 
  they 
  must 
  possess 
  a 
  

   velocity 
  practically 
  that 
  of 
  light, 
  and 
  a 
  kinetic 
  energy 
  many 
  

   times 
  that 
  of 
  the 
  ordinary 
  ^-rays. 
  In 
  view 
  of 
  the 
  great 
  

   decrease 
  in 
  penetrating 
  power 
  which 
  a 
  very 
  slight 
  diminution 
  

   of 
  velocity 
  appears 
  to 
  produce 
  in 
  this 
  type 
  of 
  radiation, 
  it 
  

   might 
  be 
  expected 
  that 
  the 
  difficultly 
  deviable 
  rays 
  w 
  ould 
  

   have 
  a 
  very 
  great 
  penetrating 
  power, 
  whereas 
  the 
  value 
  

   found 
  was 
  actually 
  less 
  than 
  the 
  normal 
  value. 
  Similar 
  

   difficultly 
  deviable 
  radiation 
  is 
  given 
  out 
  also 
  by 
  radium, 
  

   although 
  here 
  the 
  value 
  of 
  Hp 
  is 
  even 
  higher^ 
  and 
  the 
  upper 
  

  

  