﻿of 
  Atoms 
  and 
  Molecules. 
  875 
  

  

  3. 
  That 
  the 
  radiation 
  emitted 
  during 
  the 
  transition 
  of 
  a 
  

   svstem 
  between 
  two 
  stationary 
  states 
  is 
  homogeneous, 
  and 
  

   that 
  the 
  relation 
  between 
  the 
  frequency 
  v 
  and 
  the 
  total 
  

   amount 
  of 
  energy 
  emitted 
  E 
  is 
  given 
  by 
  E 
  = 
  7iy, 
  where 
  h 
  is 
  

   Planck's 
  constant. 
  

  

  4. 
  That 
  the 
  different 
  stationary 
  states 
  of 
  a 
  simple 
  system 
  

   consisting 
  of 
  an 
  electron 
  rotating 
  round 
  a 
  positive 
  nucleus 
  

   are 
  determined 
  by 
  the 
  condition 
  that 
  the 
  ratio 
  between 
  the 
  

   total 
  energy, 
  emitted 
  during 
  the 
  formation 
  of 
  the 
  con 
  figura- 
  

   tion, 
  and 
  the 
  frequency 
  of 
  revolution 
  of 
  the 
  electron 
  is 
  an 
  

  

  entire 
  multiple 
  of 
  ~ 
  } 
  . 
  Assuming 
  that 
  the 
  orbit 
  of 
  the 
  

  

  electron 
  is 
  circular, 
  this 
  assumption 
  is 
  equivalent 
  with 
  the 
  

   assumption 
  that 
  the 
  angular 
  momentum 
  of 
  the 
  electron 
  round 
  

  

  the 
  nucleus 
  is 
  equal 
  to 
  an 
  entire 
  multiple 
  of 
  — 
  -. 
  

  

  2.TT 
  

  

  5. 
  That 
  the 
  " 
  permanent 
  " 
  state 
  of 
  any 
  atomic 
  system 
  — 
  i. 
  e. 
  y 
  

   the 
  state 
  in 
  which 
  the 
  energy 
  emitted 
  is 
  maximum 
  — 
  is 
  

   determined 
  by 
  the 
  condition 
  that 
  the 
  angular 
  momentum 
  of 
  

  

  every 
  electron 
  round 
  the 
  centre 
  of 
  its 
  orbit 
  is 
  equal 
  to 
  — 
  . 
  

  

  It 
  is 
  shown 
  that, 
  applying 
  these 
  assumptions 
  to 
  Rutherford's 
  

   atom 
  model, 
  it 
  is 
  possible 
  to 
  account 
  for 
  the 
  laws 
  of 
  Balmer 
  

   and 
  Rydberg 
  connecting 
  the 
  frequency 
  of 
  the 
  different 
  lines 
  

   in 
  the 
  line-spectrum 
  of 
  an 
  element. 
  Further, 
  outlines 
  are 
  

   given 
  of 
  a 
  theory 
  of 
  the 
  constitution 
  of 
  the 
  atoms 
  of 
  the 
  

   elements 
  and 
  of 
  the 
  formation 
  of 
  molecules 
  of 
  chemical 
  

   combinations, 
  which 
  on 
  several 
  points 
  is 
  shown 
  to 
  be 
  in 
  

   approximate 
  agreement 
  with 
  experiments. 
  

  

  The 
  intimate 
  connexion 
  between 
  the 
  present 
  Iheory 
  and 
  

   modern 
  theories 
  of 
  the 
  radiation 
  from 
  a 
  black 
  body 
  and 
  of 
  

   specific 
  heat 
  is 
  evident 
  ; 
  again, 
  since 
  on 
  the 
  ordinary 
  electro- 
  

   dynamics 
  the 
  magnetic 
  moment 
  due 
  to 
  an 
  electron 
  rotating 
  

   in 
  a 
  circular 
  orbit 
  is 
  proportional 
  to 
  the 
  angular 
  momentum, 
  

   we 
  shall 
  expect 
  a 
  clo?e 
  relation 
  to 
  the 
  theory 
  of 
  magnetons 
  

   proposed 
  by 
  Weiss. 
  The 
  development 
  of 
  a 
  detailed 
  theory 
  of 
  

   heat 
  radiation 
  and 
  of 
  magnetism 
  on 
  the 
  basis 
  of 
  the 
  present 
  

   theory 
  claims, 
  however, 
  the 
  introduction 
  of 
  additional 
  as- 
  

   sumptions 
  about 
  the 
  behaviour 
  of 
  bound 
  electrons 
  in 
  an 
  

   electromagnetic 
  field. 
  The 
  writer 
  hopes 
  to 
  return 
  to 
  these 
  

   questions 
  later. 
  

  

  