﻿:248 
  

  

  Prof. 
  R. 
  W. 
  Wood 
  on 
  

  

  excited 
  by 
  5790. 
  Similar 
  complications, 
  of 
  course, 
  occur 
  at 
  

   other 
  higher 
  orders. 
  

  

  If 
  we 
  could 
  excite 
  the 
  iodine 
  absorption 
  lines 
  one 
  at 
  a 
  time 
  

   there 
  would 
  be 
  no 
  difficulty 
  in 
  finding 
  out 
  how 
  the 
  groups 
  

   are 
  built 
  up, 
  but 
  thi3 
  is 
  impossible 
  with 
  present 
  facilities. 
  

  

  By 
  varying 
  the 
  voltage 
  at 
  which 
  the 
  mercury 
  lamp 
  

   operates, 
  and 
  by 
  filtering 
  the 
  light 
  through 
  bromine 
  vapour, 
  

   some 
  clues 
  have 
  been 
  obtained 
  regarding 
  the 
  relations 
  existing 
  

   between 
  the 
  absorption 
  lines 
  and 
  the 
  lines 
  forming 
  the 
  groups, 
  

   but 
  a 
  complete 
  analysis 
  has 
  not 
  yet 
  been 
  made. 
  

  

  In 
  fig. 
  4 
  I 
  have 
  given 
  a 
  diagram 
  of 
  the 
  groups 
  up 
  to 
  the 
  

  

  Fig. 
  4. 
  

   I 
  2 
  3 
  

  

  45 
  6 
  7 
  8 
  

  

  I 
  

  

  Ml 
  ft 
  I 
  

  

  ■ 
  

  

  m 
  

  

  I 
  

  

  M 
  M 
  1 
  

  

  li? 
  

  

  , 
  KM 
  ». 
  

  

  1 
  

  

  ;,•• 
  | 
  ii 
  

  

  1 
  i 
  

  

  J. 
  

  

  V 
  

  

  ! 
  I 
  V 
  I 
  

  

  I 
  I 
  

  

  I 
  I 
  

  

  I 
  I 
  

  

  I 
  I 
  

  

  I 
  

  

  I 
  

  

  J 
  I 
  

  

  Order. 
  

  

  

   I 
  

  

  2 
  

  

  3 
  

  

  4 
  

  

  5 
  

  

  6 
  

  

  7 
  

  

  8 
  

  

  9 
  

  

  10 
  

  

  N 
  

  

  12 
  

  

  13 
  

  

  14 
  

  

  15 
  

  

  16 
  

  

  17 
  

  

  seventeenth 
  order 
  excited 
  by 
  the 
  green 
  mercury 
  line 
  of 
  the 
  

   quartz 
  lamp 
  operating 
  at 
  115 
  volts. 
  The 
  doublets 
  (lines 
  6 
  

   and 
  7) 
  excited 
  by 
  the 
  Cooper-Hewitt 
  lamp 
  appear 
  in 
  all 
  of 
  

   these 
  groups, 
  though 
  they 
  are 
  relatively 
  faint 
  owing 
  to 
  the 
  

   reversal 
  of 
  the 
  exciting 
  line, 
  and 
  these 
  doublets 
  are 
  brought 
  

   into 
  coincidence 
  in 
  the 
  diagram. 
  

  

  When 
  the 
  iodine 
  is 
  excited 
  by 
  the 
  lamp 
  operating 
  at 
  

   €0 
  volts, 
  lines 
  2, 
  4, 
  5, 
  6, 
  and 
  7 
  appear 
  in 
  the 
  group 
  of 
  

  

  