﻿Analysis 
  of 
  ft 
  Rays 
  from 
  Radium 
  B 
  and 
  Radium 
  C. 
  723 
  

  

  found 
  to 
  be 
  in 
  good 
  agreement 
  with 
  those 
  previously 
  tabu- 
  

   lated 
  by 
  Danysz 
  *. 
  The 
  a-ray 
  tube 
  could 
  be 
  used 
  for 
  

   determination 
  of 
  ft 
  rays 
  from 
  radium 
  B 
  and 
  together 
  of 
  

   velocities 
  not 
  less 
  than 
  "67 
  of 
  that 
  of 
  light. 
  For 
  the 
  lower 
  

   velocities, 
  a 
  fine 
  wire 
  was 
  made 
  intensely 
  active 
  by 
  exposure 
  

   in 
  a 
  capillary 
  tube 
  to 
  about 
  150 
  millicuries 
  of 
  purified 
  

   emanation. 
  Since 
  here 
  no 
  correction 
  for 
  absorption 
  of 
  the 
  

   ft 
  rays 
  is 
  required, 
  the 
  measurements 
  afforded 
  a 
  useful 
  check 
  

   on 
  the 
  corrections 
  made 
  in 
  some 
  of 
  the 
  lower 
  velocity 
  lines 
  

   obtained 
  with 
  the 
  a-ray 
  tube. 
  

  

  From 
  the 
  experiments 
  of 
  Hahn, 
  Baeyer, 
  and 
  Meitner, 
  it 
  

   was 
  known 
  that 
  of 
  nine 
  strong 
  groups 
  of 
  ft 
  rays, 
  five 
  were 
  

   due 
  to 
  radium 
  B, 
  and 
  the 
  remaining 
  four 
  to 
  radium 
  C. 
  Since 
  

   it 
  was 
  of 
  great 
  importance 
  to 
  distinguish 
  definitely 
  between 
  

   the 
  lines 
  to 
  be 
  ascribed 
  to 
  radium 
  B 
  and 
  radium 
  C, 
  a 
  large 
  

   number 
  of 
  experiments 
  were 
  made 
  using 
  pure 
  radium 
  C 
  as 
  

   a 
  source. 
  This 
  was 
  obtained 
  by 
  von 
  Lerch's 
  method, 
  by 
  

   immersing 
  a 
  nickel 
  wire 
  about 
  1*2 
  cm. 
  long 
  and 
  0*3 
  mm. 
  

   diameter 
  in 
  a 
  solution 
  of 
  the 
  active 
  deposit 
  ot 
  radium 
  in 
  hot 
  

   hydrochloric 
  acid. 
  By 
  the 
  use 
  of 
  large 
  quantities 
  of 
  eman- 
  

   ation 
  in 
  narrow 
  tubes, 
  it 
  was 
  found 
  possible 
  to 
  make 
  the 
  wire 
  

   so 
  active 
  as 
  to 
  equal 
  in 
  y 
  ray 
  effect 
  50 
  milligrams 
  of 
  radium 
  

   in 
  equilibrium. 
  To 
  avoid 
  all 
  possibility 
  of 
  admixture 
  of 
  

   radium 
  B, 
  the 
  nickel 
  wire 
  was 
  not 
  introduced 
  into 
  the 
  

   solution 
  until 
  20 
  minutes 
  after 
  the 
  withdrawal 
  of 
  the 
  eman- 
  

   ation. 
  Not 
  a 
  single 
  trace 
  of 
  even 
  the 
  strongest 
  lines 
  of 
  

   radium 
  B 
  was 
  detected 
  in 
  any 
  of 
  these 
  photographs. 
  On 
  the 
  

   other 
  hand, 
  the 
  wire 
  was 
  sufficiently 
  active 
  to 
  bring 
  out 
  all 
  

   but 
  the 
  faintest 
  of 
  the 
  radium 
  C 
  lines 
  observed 
  with 
  the 
  

   relatively 
  much 
  stronger 
  source 
  afforded 
  by 
  the 
  a-ray 
  tube. 
  

   The 
  advantage 
  of 
  using 
  a 
  wide 
  slit 
  was 
  especially 
  marked 
  in 
  

   the 
  experiment 
  with 
  radium 
  C. 
  It 
  was 
  found 
  that 
  the 
  lines 
  

   of 
  the 
  spectrum 
  of 
  radium 
  C 
  extended 
  even 
  into 
  the 
  regions 
  

   occupied 
  by 
  the 
  lowest 
  velocity 
  lines 
  of 
  radium 
  B, 
  although 
  

   in 
  the 
  photographs 
  taken 
  with 
  the 
  sources 
  containing 
  both 
  ft- 
  

   ray 
  products, 
  they 
  were 
  to 
  a 
  large 
  extent 
  masked 
  by 
  the 
  

   strong 
  photographic 
  effect 
  of 
  the 
  radium 
  B 
  rays. 
  As 
  a 
  result 
  

   of 
  our 
  experiments, 
  we 
  have 
  found 
  that 
  radium 
  C 
  emits 
  a 
  

   very 
  large 
  number 
  of 
  distinct 
  groups 
  of 
  ft 
  rays 
  : 
  in 
  all 
  we 
  

   have 
  observed 
  more 
  than 
  50 
  on 
  the 
  radium 
  C 
  plates 
  alone. 
  

   In 
  addition, 
  there 
  are 
  a 
  number 
  of 
  other 
  lines 
  which 
  can 
  be 
  

   seen 
  only 
  with 
  great 
  difficulty 
  with 
  specially 
  arranged 
  

   illumination. 
  Only 
  those 
  lines 
  are 
  included 
  in 
  our 
  list 
  which 
  

   have 
  been 
  definitely 
  located 
  on 
  several 
  photographs 
  with 
  at 
  

   least 
  two 
  different 
  fields. 
  There 
  are 
  very 
  great 
  variations 
  in 
  

   * 
  Danysz, 
  Compt, 
  Rend. 
  cliv. 
  p. 
  1502 
  (1912). 
  

  

  