﻿in 
  the 
  Magnetic 
  Field. 
  335 
  

  

  distinct 
  doublets 
  have 
  been 
  obtained 
  on 
  the 
  photographic 
  plate, 
  

   showing 
  that 
  the 
  gases 
  are 
  subject 
  to 
  the 
  influence 
  of 
  the 
  

   magnetic 
  field, 
  but 
  in 
  no 
  exceptionally 
  marked 
  degree. 
  The 
  

   photographs 
  which 
  I 
  have 
  already 
  taken, 
  indeed, 
  show 
  a 
  re- 
  

   solution 
  of 
  the 
  violet 
  air 
  lines 
  which 
  is 
  only 
  about 
  two-thirds 
  

   that 
  produced 
  on 
  the 
  violet 
  lines 
  of 
  zinc 
  and 
  cadmium. 
  

  

  The 
  study 
  of 
  these 
  substances 
  has 
  consequently 
  been 
  post- 
  

   poned 
  till 
  a 
  stronger 
  magnetic 
  field 
  is 
  obtained, 
  which 
  I 
  trust 
  

   to 
  have 
  soon 
  at 
  my 
  disposal. 
  

  

  Measurements. 
  

  

  Although 
  from 
  time 
  to 
  time 
  measurements 
  have 
  been 
  made 
  

   on 
  various 
  photographic 
  plates, 
  in 
  order 
  to 
  compare 
  the 
  effects 
  

   produced 
  on 
  different 
  lines 
  and 
  different 
  substances, 
  yet, 
  so 
  

   far, 
  no 
  systematic 
  attempt 
  has 
  been 
  made 
  at 
  exact 
  quantita- 
  

   tive 
  determination, 
  for 
  it 
  did 
  not 
  appear 
  possible 
  to 
  turn 
  such 
  

   work 
  to 
  good 
  account 
  until 
  the 
  resolution 
  of 
  all 
  the 
  lines 
  had 
  

   been 
  effected 
  in 
  a 
  measurable 
  form, 
  or 
  at 
  least 
  until 
  the 
  further 
  

   resolution 
  (which 
  it 
  is 
  hoped 
  may 
  be 
  soon 
  obtained) 
  has 
  been 
  

   effected. 
  

  

  In 
  the 
  meantime, 
  however, 
  the 
  following 
  numbers 
  will 
  show 
  

   the 
  general 
  trend 
  of 
  the 
  effect 
  in 
  the 
  case 
  of 
  a 
  few 
  conspicuous 
  

   lines. 
  The 
  strength 
  of 
  the 
  magnetic 
  field 
  was 
  not 
  accurately 
  

   determined, 
  and 
  indeed 
  was 
  of 
  little 
  importance 
  for 
  our 
  present 
  

   purpose, 
  but 
  it 
  may 
  be 
  taken 
  at 
  something 
  over 
  20,000 
  C.G.S. 
  

   units 
  roughly. 
  One 
  millimetre 
  on 
  the 
  photographic 
  negative 
  

   corresponds 
  to 
  2*6 
  Angstrom-units. 
  

  

  In 
  the 
  case 
  of 
  cadmium 
  we 
  have 
  : 
  — 
  

  

  

  Distance 
  between 
  side 
  lines 
  

  

  Wave-length. 
  

  

  of 
  triplet 
  in 
  ^^ 
  millim. 
  approx, 
  

  

  5086 
  

  

  29 
  

  

  4800 
  

  

  41 
  

  

  4678 
  

  

  43-5 
  

  

  4413 
  

  

  23 
  

  

  3613 
  

  

  17 
  

  

  3610 
  

  

  17 
  

  

  ase 
  of 
  zinc 
  we 
  find 
  

  

  : 
  — 
  

  

  

  Distance 
  between 
  side 
  lines 
  

  

  Wave-length. 
  

  

  of 
  triplet 
  in 
  T 
  ^ 
  millim. 
  approx, 
  

  

  4810-7 
  

  

  29 
  

  

  4722 
  

  

  39 
  

  

  4680 
  

  

  43 
  

  

  4058 
  

  

  18 
  

  

  3683 
  

  

  17 
  

  

  2 
  A 
  2 
  

  

  