﻿Bajjs 
  and 
  Product 
  of 
  Uranium 
  X. 
  863 
  

  

  limit 
  does 
  not 
  appear 
  to 
  be 
  reached 
  at 
  9000 
  io 
  11,000. 
  

   Further 
  study 
  may 
  show 
  that 
  they 
  are 
  to 
  be 
  connected 
  with 
  

   the 
  scattering 
  of 
  the 
  /3-rays, 
  though 
  the 
  experiments 
  done 
  

   rather 
  point 
  to 
  the 
  view 
  that 
  they 
  may 
  be 
  a 
  new 
  kind 
  of 
  

   radiation. 
  So 
  far 
  attention 
  has 
  been 
  concentrated 
  rather 
  

   upon 
  the 
  main 
  problem. 
  

  

  The 
  electroscope 
  used 
  for 
  hydrogen 
  had 
  a 
  very 
  thin 
  mica 
  

   screen, 
  thick 
  enough 
  to 
  absorb 
  a-rays, 
  hinged 
  inside, 
  which 
  

   could 
  be 
  turned 
  up 
  or 
  down 
  from 
  the 
  outside, 
  without 
  

   opening 
  the 
  instrument, 
  to 
  uncover 
  or 
  cover 
  the 
  preparation 
  

   at 
  will. 
  The 
  first 
  measurements, 
  with 
  the 
  third 
  set 
  of 
  

   preparations, 
  were 
  interfered 
  with 
  somewhat 
  by 
  difficulties 
  

   encountered 
  in 
  making 
  and 
  keejdng 
  the 
  electroscope 
  perfectly 
  

   ^as-tight. 
  Later 
  a 
  new 
  instrument 
  with 
  properly 
  soldered 
  

   j 
  ints 
  throughout 
  was 
  constructed 
  and 
  is 
  now 
  used 
  entirely. 
  

   There 
  were 
  three 
  preparations 
  in 
  the 
  third 
  set, 
  two 
  practically 
  

   identical 
  in 
  every 
  particular, 
  containing 
  initially 
  the 
  uranium 
  

   X 
  in 
  equilibrium 
  with 
  5*1 
  kilograms 
  of 
  uranium, 
  and 
  a 
  

   third 
  containing 
  that 
  of 
  2 
  kilograms, 
  as 
  measured 
  by 
  means 
  

   of 
  the 
  7-radiation. 
  They 
  all 
  show^ed 
  the 
  same 
  behaviour, 
  

   and 
  one 
  only 
  of 
  the 
  two 
  stronger 
  preparations 
  need 
  be 
  

   considered 
  here. 
  It 
  weighed 
  200 
  milligrams. 
  Measurements 
  

   were 
  done 
  in 
  hydrogen 
  only. 
  No 
  evidence 
  of 
  a 
  growth 
  of 
  

   a-rays 
  either 
  initially 
  or 
  at 
  any 
  subsequent 
  time 
  w^as 
  obtained. 
  

   The 
  mean 
  of 
  the 
  first 
  five 
  observations 
  over 
  the 
  first 
  28 
  days 
  

   gave 
  14 
  for 
  the 
  a-rays, 
  which, 
  corrected 
  for 
  the 
  difference 
  

   between 
  the 
  two 
  instruments, 
  gives 
  16 
  for 
  the 
  leak 
  in 
  terms 
  

   of 
  the 
  present 
  instrument. 
  The 
  actual 
  observations 
  varied 
  a 
  

   few 
  per 
  cent, 
  from 
  the 
  mean 
  for 
  the 
  reason 
  staled. 
  Sub- 
  

   sequent 
  measurements 
  with 
  the 
  new 
  electroscope 
  76, 
  99, 
  and 
  

   137 
  days 
  from 
  the 
  start, 
  gave 
  for 
  the 
  a-radiation 
  17, 
  17*2, 
  

   and 
  16'6 
  respectively. 
  

  

  In 
  the 
  fourth 
  se})aration 
  there 
  was 
  one 
  preparation 
  only, 
  

   weighing 
  77*6 
  milligrams, 
  and 
  coTitaining 
  initially 
  the 
  

   uranium 
  X 
  in 
  equilibrium 
  w^itli 
  5'05 
  kilogi-ams 
  of 
  uranium. 
  

   The 
  measurements 
  of 
  the 
  a-radiation 
  were 
  done 
  at 
  first 
  both 
  

   in 
  hydrogen 
  and 
  air. 
  Those 
  in 
  liydrogen, 
  at 
  different 
  times 
  

   from 
  preparation, 
  are 
  given 
  in 
  the 
  following 
  table. 
  They 
  

   are 
  the 
  most 
  accurate 
  so 
  far 
  done 
  and 
  are 
  all 
  comparable 
  with 
  

   one 
  another. 
  

  

  I 
  

   Time 
  (dajs). 
  I 
  

  

  a-rajs 
  .''S*6 
  

  

  0-5 
  

  

  10 
  20: 
  3 
  

  

  40 
  

  

  39-7 
  I36-8 
  ;J8-9 
  390 
  392 
  37-2 
  371 
  I 
  39-8' 
  405' 
  

  

  18 
  33 
  

  

  