﻿Chemistry 
  and 
  Physics. 
  381 
  

  

  twenty 
  minutes 
  and 
  the 
  latter 
  of 
  about 
  two 
  hours. 
  The 
  two 
  

   yellow 
  lines 
  were 
  also 
  examined, 
  but 
  no 
  good 
  photographs 
  

   obtained 
  from 
  them. 
  The 
  special 
  results 
  obtained 
  in 
  each 
  case 
  

   are 
  given 
  in 
  detail 
  with 
  a 
  series 
  of 
  photographs, 
  both 
  for 
  the 
  

   single- 
  and 
  double-order 
  condition. 
  Observations 
  were 
  made 
  

   both 
  across 
  and 
  along 
  the 
  lines 
  of 
  force. 
  With 
  respect 
  to 
  the 
  

   blue 
  line 
  (4358), 
  it 
  was 
  found, 
  for 
  example, 
  that 
  under 
  a 
  weak 
  mag- 
  

   netic 
  field 
  the 
  line 
  appears 
  as 
  a 
  triplet 
  ; 
  as 
  the 
  strength 
  of 
  

   the 
  field 
  increases 
  the 
  lower 
  component 
  splits 
  into 
  a 
  doublet 
  and 
  

   the 
  line 
  into 
  a 
  quartet. 
  As 
  seen 
  in 
  the 
  single 
  order 
  photograph, 
  

   the 
  line 
  finally 
  becomes 
  a 
  sextet, 
  the 
  field 
  having 
  a 
  strength 
  of 
  

   23,400 
  units. 
  The 
  green 
  line 
  (5460) 
  in 
  a 
  weak 
  field 
  (6000 
  units) 
  

   splits 
  into 
  a 
  triplet; 
  with 
  increase 
  of 
  strength 
  the 
  inner 
  compo- 
  

   nent 
  splits 
  into 
  a 
  triplet, 
  while 
  each 
  of 
  the 
  outer 
  lines 
  splits 
  into 
  

   a 
  doublet, 
  the 
  resultant 
  being 
  a 
  septet 
  ; 
  the 
  outer 
  lines, 
  however, 
  

   are 
  really 
  due 
  to 
  three 
  orders. 
  

  

  The 
  authors 
  close 
  their 
  paper 
  with 
  the 
  following 
  remarks 
  

   regarding 
  the 
  working 
  of 
  the 
  instrument 
  : 
  

  

  "In 
  order, 
  therefore, 
  to 
  make 
  this 
  valuable 
  instrument 
  more 
  

   serviceable 
  for 
  this 
  class 
  of 
  work, 
  attention 
  should 
  be 
  directed 
  

   to 
  the 
  increase 
  of 
  the 
  constant 
  without 
  too 
  much 
  diminution 
  of 
  

   the 
  resolving 
  power. 
  As 
  suggested 
  by 
  Michelson, 
  this 
  might 
  be 
  

   done 
  by 
  surrounding 
  the 
  instrument, 
  say, 
  with 
  water. 
  This, 
  how- 
  

   ever, 
  would 
  reduce 
  the 
  resolving 
  power 
  to 
  only 
  one-third 
  of 
  its 
  

   original 
  value. 
  A 
  better 
  suggestion 
  is 
  that 
  of 
  using 
  thinner 
  

   plates 
  for 
  the 
  instrument 
  and 
  more 
  of 
  them. 
  The 
  plates 
  might 
  

   with 
  advantage 
  be 
  made, 
  say 
  4 
  mm 
  thick 
  with, 
  say, 
  thirty 
  plates 
  

   and 
  # 
  5 
  mm 
  steps, 
  or 
  even 
  -25 
  mm 
  steps. 
  This 
  would, 
  we 
  believe, 
  

   make 
  a 
  more 
  useful 
  instrument 
  for 
  this 
  work 
  than 
  one 
  consisting 
  

   of 
  thirty 
  8 
  mm 
  plates, 
  though 
  theoretically 
  the 
  resolving-power 
  is 
  

   only 
  half 
  what 
  it 
  would 
  be 
  in 
  the 
  latter 
  case. 
  There 
  is, 
  of 
  course, 
  

   no 
  doubt 
  that 
  this 
  instrument 
  forms 
  a 
  most 
  valuable 
  addition 
  to 
  

   the 
  apparatus 
  available 
  for 
  work 
  on 
  the 
  Zeeman 
  effect." 
  

  

  5. 
  Effects 
  of 
  ultra-violet 
  light 
  on 
  gaseous 
  bodies. 
  — 
  Much 
  

   attention 
  has 
  been 
  paid 
  to 
  the 
  effect 
  of 
  the 
  X-rays 
  on 
  air 
  and 
  

   gases. 
  Under 
  the 
  action 
  of 
  the 
  cathode 
  and 
  X-rays, 
  air 
  becomes 
  

   a 
  conductor, 
  its 
  oxygen 
  is 
  partially 
  converted 
  into 
  ozone 
  and 
  

   nuclei 
  of 
  steam 
  condensation 
  are 
  formed 
  in 
  it. 
  P. 
  Lenard 
  calls 
  

   attention 
  to 
  the 
  fact 
  that 
  ultra-violet 
  light 
  exerts 
  similar 
  effects. 
  

   In 
  his 
  experiments 
  on 
  steam 
  condensation 
  by 
  means 
  of 
  ultra- 
  

   violet 
  light, 
  it 
  was 
  found 
  that 
  the 
  light 
  from 
  aluminum 
  spark 
  

   terminals 
  was 
  far 
  more 
  operative 
  than 
  that 
  from 
  other 
  metals. 
  

   The 
  following 
  is 
  the 
  list 
  of 
  metals 
  and 
  distances 
  at 
  which 
  the 
  

   working 
  of 
  their 
  ultra-violet 
  radiations 
  began 
  to 
  be 
  noticeable: 
  

  

  Al 
  Cd 
  Sn 
  Pb 
  Zn 
  Mg 
  

  

  50 
  36 
  27 
  20 
  18 
  12 
  cm. 
  

  

  The 
  region 
  of 
  the 
  spectrum 
  where 
  the 
  effects 
  of 
  ultra-violet 
  

   light 
  on 
  gaseous 
  bodies 
  begins 
  is 
  that 
  where 
  the 
  measures 
  of 
  dis- 
  

   persion 
  end. 
  The 
  rays 
  concerned 
  in 
  these 
  peculiar 
  effects 
  have 
  

  

  