﻿1030 
  Mr. 
  H. 
  a. 
  J. 
  Moseley 
  on 
  the 
  

  

  and 
  the 
  V 
  only 
  a 
  trace 
  of 
  Ou. 
  No 
  other 
  lines 
  have 
  been 
  

   found 
  ; 
  bat 
  a 
  search 
  over 
  a 
  wide 
  range 
  of 
  wave-lengths 
  

   has 
  been 
  made 
  only 
  for 
  one 
  or 
  two 
  elements, 
  and 
  perhaps 
  

   prolonged 
  exposures, 
  which 
  have 
  not 
  yet 
  been 
  attempted, 
  

   will 
  show 
  more 
  complex 
  spectra. 
  The 
  prevalence 
  of 
  lines 
  

   due 
  to 
  impurities 
  suggests 
  that 
  this 
  may 
  prove 
  a 
  powerful 
  

   method 
  of 
  chemical 
  analysis. 
  Its 
  advantage 
  over 
  ordinary 
  

   spectroscopic 
  methods 
  lies 
  in 
  the 
  simplicity 
  of 
  the 
  spectra 
  

   and 
  the 
  impossibility 
  of 
  one 
  substance 
  masking 
  the 
  radiation 
  

   from 
  another. 
  It 
  may 
  even 
  lead 
  to 
  the 
  discovery 
  of 
  missing- 
  

   elements, 
  as 
  it 
  will 
  be 
  possible 
  to 
  predict 
  the 
  position 
  of 
  

   their 
  characteristic 
  lines. 
  

  

  It 
  will 
  be 
  seen 
  from 
  Table 
  I. 
  that 
  the 
  wave-lengths 
  calcu- 
  

   lated 
  from 
  the 
  two 
  orders 
  are 
  in 
  good 
  agreement. 
  The 
  third 
  

   order 
  gives 
  the 
  stronger 
  reflexion, 
  and 
  as 
  the 
  angles 
  dealt 
  

   with 
  are 
  the 
  larger 
  these 
  results 
  are 
  the 
  more 
  accurate. 
  

   The 
  similarity 
  of 
  the 
  different 
  spectra 
  is 
  shown 
  by 
  the 
  fact 
  

   that 
  the 
  two 
  lines 
  a 
  and 
  /3 
  remain 
  approximately 
  constant, 
  

   not 
  only 
  in 
  relative 
  intensity 
  but 
  also 
  in 
  relative 
  wave- 
  

   length. 
  The 
  frequency 
  of 
  increases, 
  however, 
  slightly 
  

   faster 
  than 
  that 
  of 
  a. 
  The 
  same 
  two 
  lines 
  a 
  strong 
  and 
  

   weak 
  constitute 
  the 
  rhodium 
  spectrum 
  examined 
  by 
  Bragg 
  *, 
  

   and 
  they 
  are 
  obviously 
  in 
  some 
  way 
  closely 
  related. 
  

   One 
  or 
  two 
  photographs 
  taken 
  with 
  the 
  radiation 
  from 
  

   platinum 
  gave 
  results 
  in 
  good 
  agreement 
  with 
  those 
  obtained 
  

   by 
  the 
  electrical 
  method, 
  and 
  no 
  trace 
  of 
  the 
  elaborate 
  system 
  

   of 
  bands 
  described 
  by 
  de 
  Broglie 
  t 
  in 
  the 
  reflexion 
  from 
  rock- 
  

   salt 
  was 
  encountered. 
  The 
  three 
  lines 
  found 
  by 
  Herveg 
  % 
  in 
  

   the 
  reflexion 
  from 
  selenite 
  doubtless 
  represent 
  part 
  of 
  the 
  

   Pt 
  spectrum 
  in 
  the 
  second 
  order. 
  The 
  actual 
  breadth 
  of 
  the 
  

   lines 
  and 
  certain 
  minute 
  details 
  in 
  their 
  structure 
  will 
  not 
  

   be 
  considered 
  here, 
  as 
  discussion 
  would 
  take 
  too 
  much 
  

   space 
  and 
  more 
  experiments 
  are 
  needed. 
  The 
  only 
  other 
  

   element 
  examined 
  was 
  tantalum. 
  In 
  this 
  case 
  the 
  radiation 
  

   belongs 
  to 
  the 
  L 
  series, 
  and 
  the 
  spectrum 
  consists 
  of 
  a 
  strong- 
  

   line 
  of 
  wave-length 
  1*525 
  x 
  10~ 
  8 
  cm., 
  two 
  others 
  of 
  less 
  

   intensity 
  at 
  1*330 
  and 
  1*287 
  x 
  10" 
  8 
  cm., 
  and 
  probably 
  some 
  

   very 
  faint 
  lines 
  also. 
  

  

  A 
  discussion 
  will 
  now 
  be 
  given 
  of 
  the 
  meaning 
  of 
  the 
  

   wave-lengths 
  found 
  for 
  the 
  principal 
  spectrum-line 
  a. 
  In 
  

   Table 
  I. 
  the 
  values 
  are 
  given 
  of 
  the 
  quantity 
  

  

  Q 
  

  

  V 
  4 
  F 
  

  

  * 
  Proc. 
  Roy. 
  Soc. 
  A. 
  lxxxix. 
  p. 
  277 
  (1913). 
  

  

  t 
  Le 
  Radium, 
  x. 
  pp. 
  186 
  & 
  245 
  (1913). 
  

  

  \ 
  Deutsch. 
  Phijs. 
  Ges. 
  Terh, 
  xv. 
  13, 
  p. 
  555 
  (1913). 
  

  

  