﻿464 
  Scientific 
  Intelligence. 
  

  

  sure 
  of 
  the 
  substance 
  to 
  cathode 
  rays, 
  to 
  sunlight, 
  or 
  to 
  heat. 
  

   They 
  were 
  not 
  deflected 
  by 
  a 
  magnetic 
  field. 
  Their 
  power 
  of 
  

   rendering 
  air 
  a 
  better 
  conductor 
  ol' 
  electricity 
  was 
  lessened 
  in 
  

   such 
  a 
  field. 
  — 
  Wied. 
  Amjb., 
  No. 
  9, 
  1899, 
  pp. 
  83-90. 
  j. 
  t. 
  

  

  6. 
  Magnetizing 
  constants 
  of 
  inorganic 
  substances. 
  — 
  Stefan 
  

   Meyer 
  has 
  made 
  an 
  extended 
  study 
  of 
  the 
  behavior 
  of 
  a 
  large 
  

   number 
  of 
  inorganic 
  substances 
  in 
  the 
  magnetic 
  field 
  and 
  gives 
  

   tabulated 
  results. 
  One 
  of 
  the 
  most 
  interesting 
  facts 
  he 
  states 
  is 
  

   in 
  regard 
  to 
  erbium. 
  In 
  the 
  combination 
  Er^Og 
  it 
  is 
  four 
  times 
  

   stronger 
  than 
  Fe^Og. 
  If 
  in 
  the 
  pure 
  metallic 
  state 
  it 
  were 
  as 
  mag- 
  

   netic 
  as 
  it 
  is 
  in 
  the 
  state 
  of 
  oxide, 
  one 
  could 
  reduce 
  the 
  weight 
  of 
  

   dynamos 
  one-sixth 
  and 
  still 
  obtain 
  the 
  same 
  output 
  as 
  when 
  iron 
  

   is 
  employed. 
  — 
  Wied. 
  Ann., 
  No. 
  9, 
  1 
  899, 
  pp. 
  236-263. 
  j. 
  t. 
  

  

  7. 
  The 
  Color 
  Seiisations 
  in 
  Terms 
  of 
  Luminosity 
  ; 
  by 
  W. 
  

   DE 
  W. 
  Abney. 
  (Abstract.) 
  — 
  This 
  paper 
  deals 
  with 
  a 
  determina- 
  

   tion 
  of 
  the 
  color 
  sensations 
  based 
  on 
  the 
  Young 
  theory 
  by 
  means 
  

   of 
  measures 
  of 
  the 
  luminosity 
  of 
  the 
  three 
  different 
  color 
  com- 
  

   ponents 
  in 
  a 
  mixed 
  light 
  which 
  matches 
  white. 
  At 
  the 
  red 
  end 
  

   of 
  the 
  spectrum 
  there 
  is 
  only 
  one 
  color 
  extending 
  to 
  near 
  C, 
  and 
  

   there 
  is 
  no 
  mixture 
  of 
  other 
  colors 
  which 
  will 
  match 
  it, 
  however 
  

   selected. 
  At 
  the 
  violet 
  end 
  of 
  the 
  spectrum, 
  from 
  the 
  extreme 
  

   violet 
  to 
  near 
  G, 
  the 
  same 
  homogeneity 
  of 
  light 
  exists, 
  but 
  it 
  is 
  

   apparently 
  due 
  to 
  the 
  stimulation 
  of 
  two 
  sensations, 
  a 
  red 
  and 
  a 
  

   blue 
  sensation, 
  the 
  latter 
  never 
  being 
  felt 
  unmixed 
  with 
  any 
  

   other. 
  Having 
  ascertained 
  this, 
  it 
  remained 
  to 
  find 
  that 
  place 
  in 
  

   the 
  spectrum 
  where 
  the 
  blue 
  sensation 
  was 
  to 
  be 
  found 
  unmixed 
  

   with 
  any 
  other 
  sensation 
  except 
  white. 
  By 
  trial 
  it 
  was 
  found 
  

   that 
  close 
  to 
  the 
  blue 
  lithium 
  line 
  this 
  was 
  the 
  case, 
  and 
  that 
  a 
  

   mixture 
  of 
  this 
  color 
  and 
  pure 
  red 
  sensation 
  gave 
  the 
  violet 
  of 
  

   the 
  spectrum 
  when 
  the 
  latter 
  was 
  mixed 
  with 
  a 
  certain 
  quantity 
  

   of 
  white. 
  The 
  red 
  and 
  blue 
  sensation 
  being 
  located, 
  it 
  remained 
  

   to 
  find 
  the 
  green 
  sensation. 
  The 
  complementary 
  color 
  to 
  the 
  red 
  

   in 
  the 
  spectrum 
  gave 
  a 
  position 
  in 
  which 
  the 
  green 
  and 
  blue 
  

   sensations 
  were 
  present 
  in 
  the 
  right 
  proportions 
  to 
  make 
  white, 
  

   and 
  a 
  point 
  nearer 
  the 
  red 
  gave 
  a 
  point 
  in 
  which 
  the 
  red 
  and 
  blue 
  

   sensations 
  were 
  present 
  in 
  such 
  proportions 
  as 
  found 
  in 
  white, 
  

   but 
  there 
  v^as 
  an 
  excess 
  of 
  green 
  sensation. 
  By 
  preliminary 
  

   trials 
  this 
  point 
  was 
  found. 
  The 
  position 
  in 
  the 
  spectrum 
  of 
  the 
  

   yellow 
  color 
  complementary 
  to 
  the 
  violet 
  was 
  also 
  found. 
  The 
  

   color 
  of 
  bichromate 
  of 
  potash 
  was 
  matched 
  by 
  using 
  a 
  pure 
  red 
  

   and 
  the 
  last-named 
  green. 
  To 
  make 
  the 
  match, 
  white 
  had 
  to 
  be 
  

   added 
  to 
  the 
  bichromate 
  color. 
  A 
  certain 
  small 
  percentage 
  of 
  

   white 
  was 
  found 
  to 
  exist 
  in 
  the 
  light 
  transmitted 
  through 
  a 
  

   bichromate 
  solution 
  with 
  which 
  the 
  match 
  was 
  made, 
  and 
  this 
  

   percentage 
  and 
  the 
  added 
  white 
  being 
  deducted 
  from 
  the 
  green 
  

   used, 
  gave 
  the 
  luminosity 
  of 
  the 
  pure 
  green 
  sensation 
  existing 
  in 
  

   the 
  spectrum 
  color 
  which 
  matched 
  the 
  bichromate. 
  Knowing 
  the 
  

   percentage 
  composition 
  in 
  luminosity 
  of 
  the 
  two 
  sensations 
  at 
  

   this 
  point, 
  the 
  luminosity 
  of 
  the 
  three 
  sensations 
  in 
  white 
  was 
  

   determined 
  by 
  matching 
  the 
  bichromate 
  color 
  with 
  the 
  yellow 
  

  

  