﻿Lea 
  — 
  Color 
  Relations 
  of 
  Atoms, 
  Jons 
  and 
  Molecules. 
  371 
  

  

  The 
  transitional 
  elements 
  titanium 
  and 
  vanadium 
  on 
  the 
  

   one 
  side 
  of 
  this 
  series 
  and 
  copper 
  on 
  the 
  other, 
  are 
  the 
  out- 
  

   liers. 
  

  

  The 
  second 
  colored 
  series 
  contains 
  the 
  well 
  known 
  group 
  

   rhodium, 
  ruthenium 
  and 
  palladium. 
  The 
  third 
  colored 
  group 
  

   contains 
  the 
  metals 
  of 
  the 
  rare 
  earths 
  followed 
  by 
  the 
  transi- 
  

   tionals 
  tantalum 
  and 
  tungsten. 
  Finally 
  the 
  colored 
  group 
  of 
  

   the 
  platinum 
  metals 
  and 
  gold. 
  These 
  and 
  the 
  remaining 
  col- 
  

   ored 
  metals 
  will 
  be 
  described 
  in 
  the 
  next 
  section. 
  

  

  One 
  metal, 
  zirconium, 
  has 
  proved 
  rebellious 
  to 
  this 
  classifica- 
  

   tion. 
  

  

  The 
  others 
  have 
  taken 
  their 
  places 
  so 
  easily 
  and 
  exactly 
  that 
  

   it 
  seems 
  as 
  if 
  there 
  must 
  be 
  something 
  inexact 
  or 
  incomplete 
  

   in 
  our 
  data 
  respecting 
  this 
  metal. 
  The 
  most 
  probable 
  supposi- 
  

   tion 
  seems 
  to 
  be 
  the 
  following. 
  Zirconium 
  nas 
  but 
  one 
  degree 
  

   of 
  oxidation 
  while 
  the 
  very 
  closely 
  allied 
  metal 
  titanium, 
  has 
  

   ions 
  that 
  are 
  colored 
  and 
  colorless 
  at 
  different 
  valencies. 
  

  

  Should 
  zirconium 
  prove 
  to 
  have 
  a 
  second 
  degree 
  of 
  oxida- 
  

   tion 
  corresponding 
  to 
  colored 
  ions, 
  it 
  would 
  be 
  brought 
  into 
  

   complete 
  analogy 
  with 
  its 
  congener 
  and 
  would 
  find 
  a 
  place 
  

   open 
  for 
  it 
  in 
  the 
  tables. 
  

  

  In 
  Table 
  II 
  it 
  would 
  take 
  the 
  vacant 
  place 
  immediately 
  fol- 
  

   lowing 
  titanium 
  and 
  between 
  that 
  metal 
  and 
  cerium. 
  As 
  a 
  

   transitional 
  metal 
  it 
  would 
  take 
  its 
  place 
  in 
  Table 
  III 
  immedi- 
  

   ately 
  before 
  niobium 
  in 
  the 
  second 
  series. 
  It 
  is 
  hardly 
  neces- 
  

   sary 
  to 
  remark 
  that 
  these 
  are 
  exactly 
  the 
  places 
  for 
  which 
  its 
  

   properties 
  fit 
  it. 
  

  

  All 
  the 
  elements 
  contained 
  in 
  Table 
  III 
  have 
  ions 
  that 
  func- 
  

   tion 
  as 
  hathions 
  only. 
  

  

  