﻿38 
  Dr. 
  A. 
  C. 
  Crehore 
  on 
  the 
  Formation 
  of 
  the 
  

  

  experiment. 
  Take, 
  for 
  example, 
  the 
  curve 
  passing 
  through 
  

   the 
  combinations 
  6-4, 
  7-4, 
  8-4, 
  9-4, 
  and 
  10-4, 
  each 
  of 
  

   which 
  gives 
  stable 
  figures. 
  This 
  shows 
  a 
  systematic 
  law 
  of 
  

   change, 
  which 
  suddenly 
  jumps, 
  when 
  there 
  are 
  15 
  electrons, 
  

   to 
  the 
  next 
  broken 
  line. 
  The 
  chart 
  shows 
  a 
  relationship 
  not 
  

   so 
  pin 
  inly 
  seen 
  from 
  the 
  table. 
  When 
  there 
  are 
  alternative 
  

   combinations 
  with 
  the 
  same 
  number 
  of 
  electrons, 
  the 
  sums 
  of 
  

   their 
  radii 
  differ. 
  

  

  The 
  names 
  of 
  the 
  elements, 
  provisionally 
  assigned 
  to 
  

   certain 
  combinations 
  o£ 
  the 
  electrons, 
  have 
  been 
  so 
  adopted 
  for 
  

   purposes 
  of 
  convenience 
  of 
  reference. 
  It 
  is 
  more 
  convenient 
  

   to 
  refer 
  to 
  the 
  combinations 
  by 
  means 
  o£ 
  a 
  chemical 
  symbol, 
  

   as 
  N 
  denoting 
  nitrogen, 
  than 
  to 
  give 
  their 
  numbers, 
  

   12 
  = 
  9 
  + 
  3. 
  The 
  assignment 
  has 
  been 
  made 
  as 
  nearly 
  correct 
  

   as 
  possible 
  in 
  accordance 
  with 
  the 
  indications 
  of 
  the 
  periodic 
  * 
  

   table 
  of 
  the 
  elements. 
  The 
  atomic 
  weights 
  of 
  the 
  elements 
  

   are 
  seen 
  to 
  correspond 
  in 
  an 
  approximate 
  manner 
  only 
  with 
  

   the 
  sum 
  of 
  the 
  radii 
  of 
  the 
  orbits 
  of 
  the 
  electrons. 
  

  

  The 
  calculated 
  radii 
  given 
  in 
  the 
  table 
  are 
  not 
  sensibly 
  

   changed 
  by 
  the 
  angular 
  velocity 
  of 
  revolution 
  of 
  the 
  whole 
  

   atom. 
  This 
  velocity 
  is 
  allowed 
  for 
  in 
  the 
  formula, 
  and 
  the 
  

   probability 
  is 
  that 
  it 
  is 
  such 
  that 
  the 
  change 
  in 
  the 
  radii 
  may 
  

   be 
  entirely 
  neglected, 
  as 
  being 
  small 
  compared 
  with 
  the 
  errors 
  

   in 
  determining 
  the 
  radii 
  by 
  experiment. 
  

  

  Part 
  II. 
  

  

  Combinations 
  of 
  Atoms. 
  

  

  The 
  atoms, 
  as 
  described, 
  have 
  been 
  determined 
  with 
  

   sufficient 
  definiteness 
  to 
  make 
  possible 
  a 
  calculation 
  of 
  the 
  

   attraction 
  or 
  repulsion 
  that 
  one 
  may 
  have 
  for 
  another. 
  This 
  

   depends 
  upon 
  the 
  expressions 
  for 
  the 
  mechanical 
  force 
  which 
  

   one 
  moving 
  electron 
  exerts 
  upon 
  another. 
  A 
  definite 
  ex- 
  

   ample 
  with 
  the 
  simplest 
  atom 
  containing 
  but 
  two 
  electrons 
  

   within 
  a 
  positive 
  sphere 
  will 
  serve 
  to 
  illustrate 
  the 
  method 
  

   of 
  procedure. 
  First, 
  suppose 
  that 
  there 
  are 
  two 
  such 
  atoms 
  

   placed 
  one 
  over 
  the 
  other 
  so 
  that 
  the 
  axes 
  of 
  their 
  orbits 
  aie 
  

   coincident, 
  and 
  their 
  planes 
  parallel. 
  Moreover, 
  suppose 
  

   for 
  simplicity 
  that 
  the 
  electrons 
  are 
  in 
  phase, 
  the 
  one 
  

   standing 
  directly 
  over 
  the 
  other, 
  all 
  four 
  lying 
  in 
  the 
  same 
  

   meridian 
  plane. 
  We 
  will 
  suppose 
  at 
  first 
  that 
  the 
  electrons 
  

   are 
  at 
  rest 
  in 
  these 
  positions, 
  for 
  there 
  are 
  then 
  the 
  ordinary 
  

   electrostatic 
  forces 
  of 
  attraction 
  and 
  repulsion 
  between 
  the 
  

   various 
  parts 
  of 
  the 
  atom. 
  As 
  soon 
  as 
  revolution 
  begins 
  

  

  * 
  A. 
  C. 
  Crehore, 
  Physical 
  Review, 
  vol. 
  xiv. 
  no. 
  4, 
  Apr. 
  1012. 
  

  

  