﻿Radium 
  and 
  other 
  Elementary 
  Substances. 
  829 
  

  

  From 
  the 
  definite 
  multiple 
  relations 
  which 
  the 
  atomic 
  

   weights 
  o£ 
  mercury, 
  lead, 
  and 
  thorium 
  have 
  to 
  those 
  of 
  the 
  

   lower 
  members 
  of 
  their 
  respective 
  series, 
  for 
  the 
  same 
  number 
  

   of 
  elementary 
  condensations, 
  there 
  is 
  abundant 
  reason 
  for 
  

   concluding 
  that 
  no 
  elements 
  exist 
  of 
  higher 
  atomic 
  weights 
  

   than 
  those 
  shown 
  in 
  each 
  series 
  of 
  my 
  tables. 
  

  

  The 
  general 
  principles 
  herein 
  set 
  forth 
  enable 
  me 
  now 
  to 
  

   deal 
  with 
  the 
  anomalously 
  high 
  value 
  assigned 
  to 
  the 
  atomic 
  

   weight 
  of 
  radium 
  in 
  the 
  most 
  recent 
  experimental 
  determi- 
  

   nations, 
  as 
  compared 
  with 
  the 
  theoretical 
  value 
  184 
  shown 
  

   in 
  my 
  tables. 
  

  

  In 
  the 
  determination 
  made 
  by 
  Mme. 
  Curie 
  with 
  the 
  chloride 
  

   the 
  atomic 
  weight 
  of 
  radium 
  was 
  calculated 
  to 
  be 
  226*. 
  

   More 
  recently, 
  Dr. 
  Thorpe, 
  F.R.S., 
  has 
  repeated 
  Mme. 
  Curie's 
  

   experiments 
  with 
  radium 
  chloride 
  and 
  obtained 
  nearly 
  the 
  

   same 
  result 
  f. 
  

  

  In 
  both 
  these 
  determinations 
  it 
  will 
  be 
  observed 
  that 
  

   beyond 
  the 
  statement 
  that 
  radium 
  is 
  a 
  bivalent 
  element, 
  no 
  

   mention 
  is 
  made 
  of 
  the 
  constitution 
  of 
  the 
  chloride 
  from 
  

   which 
  the 
  results 
  were 
  obtained, 
  i. 
  e. 
  whether 
  a 
  protochloride 
  

   according 
  to 
  Dumas, 
  Marignac, 
  and 
  Berthelot, 
  or 
  a 
  dichloride 
  

   in 
  agreement 
  with 
  Cannizzaro. 
  This 
  omission 
  has, 
  however, 
  

   been 
  supplied 
  in 
  Mme. 
  Curie's 
  ' 
  Thesis 
  on 
  Radioactive 
  

   Substances,' 
  in 
  which 
  the 
  formula 
  of 
  radium 
  chloride 
  is 
  

   written 
  RaCl 
  2 
  , 
  and, 
  consequently, 
  a 
  dichloride. 
  

  

  A 
  glance 
  at 
  my 
  complete 
  table 
  of 
  atomic 
  weights 
  will 
  

   show 
  that 
  the 
  several 
  series 
  of 
  elements, 
  Hn-H7n, 
  are 
  in 
  

   the 
  order 
  of 
  their 
  quantivalence. 
  It 
  will 
  also 
  be 
  seen 
  that 
  

   the 
  valencies 
  of 
  the 
  series 
  Hn 
  and 
  H2n 
  are 
  determined 
  solely 
  

   by 
  the 
  multiple 
  relations 
  herein 
  set 
  forth, 
  as 
  distinguished 
  

   from 
  the 
  estimated 
  quantities 
  shown 
  in 
  periodic 
  systems 
  of 
  

   the 
  elements. 
  

  

  That 
  the 
  univalent 
  halogens 
  are 
  negative 
  analogues 
  of 
  the 
  

   univalent 
  alkaline 
  metals 
  in 
  homologous 
  positions 
  in 
  my 
  

   table, 
  is 
  evident 
  from 
  their 
  numerical, 
  physical, 
  and 
  chemical 
  

   relations, 
  just 
  as 
  the 
  bivalent 
  oxygen 
  series 
  have 
  the 
  like 
  

   relations 
  to 
  the 
  bivalent 
  alkaline-earth 
  metals. 
  The 
  formula 
  

   for 
  radium 
  dioxide, 
  like 
  that 
  of 
  barium, 
  will 
  therefore 
  be 
  

   Ra0 
  2 
  . 
  Now 
  it 
  is 
  well 
  known 
  that 
  chlorine 
  combines 
  with 
  

   the 
  alkaline 
  and 
  alkaline 
  earth 
  metals 
  in 
  one 
  proportion 
  only; 
  

   and 
  according 
  to 
  Dalton's 
  first 
  canon 
  of 
  chemical 
  synthesis 
  

   a 
  such 
  combination 
  must 
  be 
  presumed 
  to 
  be 
  a 
  binary 
  one 
  "J. 
  

   Consequently, 
  until 
  radium 
  can 
  be 
  shown 
  to 
  have 
  two 
  

  

  * 
  CompUs 
  Rendus, 
  tome 
  cxlv. 
  p. 
  422 
  (1907). 
  

  

  t 
  Proc. 
  Koy. 
  Soc. 
  vol. 
  lxxx. 
  p. 
  307 
  (1908). 
  

  

  + 
  Dalton's 
  ' 
  New 
  System 
  of 
  Chemical 
  Philosophy,' 
  p. 
  214 
  (1842). 
  

  

  