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  Lea 
  — 
  Color 
  Relations 
  of 
  Atoms, 
  Ions 
  and 
  Molecules. 
  

  

  This 
  exclusion 
  cannot 
  be 
  explained 
  or 
  accounted 
  for 
  in 
  any 
  

   way. 
  Hydrogen 
  simply 
  will 
  not 
  fit 
  in 
  to 
  a 
  proper 
  place, 
  but 
  

   has 
  to 
  be 
  excluded 
  to 
  obtain 
  symmetry. 
  

  

  Then 
  there 
  are 
  the 
  three 
  metals, 
  iron, 
  cobalt 
  and 
  nickel 
  and 
  

   the 
  six 
  platinum 
  metals. 
  For 
  all 
  of 
  these 
  there 
  is 
  no 
  place, 
  

   and 
  one 
  has 
  to 
  be 
  forcibly 
  made. 
  Whether 
  this 
  is 
  accom- 
  

   plished 
  by 
  making 
  them 
  a 
  fragmentary 
  and 
  disjointed 
  eighth 
  

   column 
  as 
  done 
  by 
  Lothair 
  Meyer 
  or 
  whether 
  they 
  are 
  inserted, 
  

   three 
  of 
  them 
  into 
  each 
  of 
  a 
  second, 
  third 
  and 
  fifth 
  vertical 
  

   column, 
  as 
  done 
  by 
  Mendeleef, 
  the 
  effect 
  is 
  in 
  either 
  case 
  

   forced 
  and 
  unnatural. 
  These 
  elements 
  cannot 
  like 
  hydrogen 
  

   be 
  simply 
  excluded, 
  they 
  must 
  be 
  placed 
  somewhere, 
  but 
  one 
  

   feels 
  the 
  symmetry 
  is 
  destroyed. 
  Another 
  most 
  serious 
  objec- 
  

   tion 
  is 
  to 
  the 
  exclusion 
  of 
  sodium 
  from 
  the 
  series 
  of 
  the 
  

   alkaline 
  metals. 
  

  

  In 
  both 
  tables 
  chromium 
  and 
  molybdenum 
  are 
  placed 
  in 
  the 
  

   oxygen 
  group 
  and 
  in 
  Mendeleef's, 
  fluorine 
  and 
  manganese 
  con- 
  

   stitute 
  a 
  group. 
  AH 
  the 
  metals 
  having 
  ions 
  colored 
  at 
  all 
  

   valencies 
  are 
  out 
  of 
  place. 
  Other 
  faults 
  might 
  be 
  cited 
  but 
  

   the 
  above 
  are 
  sufficient 
  to 
  show 
  that 
  the 
  periodic 
  law 
  is 
  a 
  

   singular 
  mixture 
  of 
  truth 
  and 
  error. 
  

  

  Periodic 
  Systems. 
  

  

  The 
  body 
  of 
  the 
  elements 
  separates 
  itself 
  as 
  we 
  have 
  seen 
  

   into 
  two 
  great 
  divisions 
  those 
  with 
  ions 
  always 
  colorless 
  and 
  

   those 
  with 
  ions 
  always 
  colored. 
  

  

  These 
  two 
  classes 
  are 
  always 
  distinct 
  and 
  the 
  elements 
  form- 
  

   ing 
  each 
  have 
  no 
  relation 
  with 
  the 
  other 
  ; 
  that 
  is 
  to 
  say, 
  we 
  shall 
  

   never 
  find 
  in 
  natural 
  groups 
  elements 
  belonging 
  to 
  more 
  than 
  

   one 
  of 
  these 
  two 
  great 
  divisions. 
  The 
  remarkable 
  manner 
  in 
  

   which 
  they 
  meet 
  at 
  particular 
  points 
  or 
  nodes 
  and 
  melt 
  into 
  

   each 
  other 
  will 
  be 
  described 
  farther 
  on. 
  At 
  present 
  we 
  have 
  

   only 
  to 
  do 
  with 
  the 
  consideration 
  of 
  classes 
  taken 
  separately. 
  

  

  First 
  Division. 
  Ions 
  all 
  Colorless. 
  

  

  And 
  first 
  as 
  to 
  the 
  colorless 
  class. 
  If 
  we 
  arrange 
  all 
  its 
  

   members 
  in 
  numerical 
  order 
  so 
  as 
  to 
  form 
  vertical 
  columns 
  of 
  

   nine 
  each, 
  then 
  if 
  we 
  read 
  the 
  horizontal 
  lines 
  we 
  shall 
  find 
  

   that 
  the 
  entire 
  class 
  of 
  elements 
  with 
  colorless 
  ions 
  is 
  divided 
  

  

  