﻿of 
  the 
  Atomic 
  Weights 
  of 
  Elementary 
  Substances. 
  735 
  

  

  as 
  they 
  are 
  found 
  in 
  the 
  palladium 
  and 
  platinum 
  groups 
  of 
  

   metals. 
  Chemists 
  have 
  already 
  observed 
  that 
  each 
  of 
  the 
  

   metals 
  of 
  the 
  palladium 
  group 
  appears 
  to 
  be 
  more 
  especially 
  

   correlated 
  with 
  some 
  particular 
  member 
  of 
  the 
  platinum 
  

   group, 
  and 
  all 
  are 
  found 
  associated 
  together 
  naturally 
  in 
  the 
  

   metallic 
  state. 
  M. 
  Sergius 
  Kern, 
  a 
  Russian 
  chemist, 
  has 
  

   discovered 
  a 
  new 
  metal 
  with 
  an 
  approximate 
  specific 
  gravity 
  

   of 
  9*39 
  which 
  he 
  classifies 
  with 
  the 
  platinums, 
  and 
  has 
  given 
  

   to 
  it 
  the 
  name 
  of 
  Davyum 
  *. 
  The 
  low 
  specific 
  gravity 
  of 
  

   this 
  element 
  indicates 
  it 
  as 
  the 
  fourth 
  member 
  of 
  the 
  palladium 
  

   group 
  of 
  metals, 
  as 
  shown 
  in 
  my 
  general 
  Table. 
  

  

  The 
  chief 
  properties 
  which 
  distinguish 
  the 
  elements 
  of 
  

   the 
  series 
  H7?i 
  are 
  their 
  high 
  fusing-point 
  and 
  their 
  passivity 
  

   in 
  the 
  presence 
  of 
  ordinary 
  reagents, 
  to 
  which 
  iron, 
  under 
  

   peculiar 
  conditions, 
  forms 
  no 
  exception. 
  

  

  Although 
  gold 
  in 
  some 
  recent 
  classifications 
  of 
  elements 
  

   has 
  been 
  separated 
  from 
  the 
  platinum 
  metals, 
  yet, 
  in 
  its 
  

   primary 
  qualities, 
  it 
  exhibits 
  closer 
  analogies 
  with 
  them 
  than 
  

   with 
  the 
  members 
  of 
  any 
  other 
  series, 
  and 
  there 
  is 
  no 
  other 
  

   place 
  vacant 
  in 
  the 
  groups 
  which 
  an 
  element 
  with 
  the 
  atomic 
  

   weight 
  and 
  physical 
  properties 
  of 
  gold 
  would 
  fit. 
  The 
  

   constant 
  association 
  in 
  nature 
  of 
  quartz, 
  hematite, 
  and 
  

   specular 
  iron 
  ores 
  with 
  gold 
  and 
  platinum 
  is 
  a 
  fact 
  fully 
  

   recognized 
  by 
  chemical 
  geologists 
  f 
  . 
  and 
  confirms 
  the 
  positions 
  

   assigned 
  for 
  Si, 
  Fe, 
  and 
  Au 
  in 
  the 
  table 
  as 
  forms 
  of 
  H7>*. 
  

  

  Although 
  I 
  have 
  designated 
  the 
  highest 
  members 
  of 
  the 
  

   series 
  H7?z 
  as 
  the 
  platinum 
  group, 
  yet 
  if 
  the 
  small 
  differences 
  

   in 
  their 
  atomic 
  weights 
  and 
  physical 
  properties 
  admit 
  of 
  

   explanation 
  by 
  the 
  assumption 
  of 
  their 
  being 
  allotropic 
  

   varieties 
  of 
  each 
  other, 
  then 
  gold, 
  palladium, 
  and 
  iron 
  may 
  

   stand 
  at 
  the 
  head 
  of 
  their 
  respective 
  groups 
  and 
  determine 
  

   the 
  species 
  to 
  which 
  the 
  varieties 
  belong. 
  It 
  is 
  no 
  objection 
  

   to 
  the 
  theory 
  of 
  the 
  members 
  of 
  the 
  respective 
  groups 
  being- 
  

   varieties 
  of 
  each 
  other 
  that 
  they 
  cannot 
  by 
  any 
  known 
  power 
  

   of 
  analysis 
  be 
  resolved 
  into 
  their 
  primaries, 
  as 
  the 
  same 
  

   objection 
  would 
  apply 
  to 
  the 
  natural 
  varieties 
  of 
  organic 
  

   species 
  determined 
  by 
  naturalists. 
  

  

  The 
  arbitrary 
  policy 
  of 
  several 
  writers 
  in 
  doubling 
  the 
  

   atomic 
  weights 
  of 
  four 
  of 
  the 
  gaseous 
  members 
  of 
  the 
  series 
  

   H7n, 
  viz. 
  : 
  neon, 
  argon, 
  krypton, 
  and 
  xenon 
  (notwithstanding 
  

   that 
  the 
  atomic 
  weights 
  of 
  nitrogen, 
  hydrogen, 
  oxygen, 
  and 
  

  

  * 
  Comptes 
  Rendns, 
  lxxxv. 
  pp. 
  72, 
  623, 
  667. 
  

  

  f 
  Bischoff 
  's 
  ' 
  Chemical 
  and 
  Physical 
  Geology,' 
  iii. 
  p. 
  534. 
  Cavendish 
  

   Soc. 
  Works. 
  Murchison's 
  ' 
  Siluria,' 
  chap. 
  17, 
  pp. 
  433-439. 
  

  

  