﻿ARCHITECTURE 
  OF 
  ATOMS 
  — 
  ABBOT. 
  165 
  

  

  most 
  striking 
  success. 
  Unfortunately 
  the 
  mathematical 
  analysis 
  be- 
  

   comes 
  hopelessly 
  involved 
  for 
  elements 
  of 
  high 
  atomic 
  weight, 
  so 
  that 
  

   such 
  verifications 
  are 
  confined 
  so 
  far 
  to 
  the 
  simpler 
  atoms, 
  such 
  as 
  

   hydrogen, 
  helium, 
  and 
  some 
  of 
  the 
  alkalis. 
  

  

  Bohr's 
  atomic 
  theory 
  received 
  complementary 
  contributions 
  useful 
  

   for 
  explaining 
  the 
  spectra 
  of 
  the 
  stars 
  from 
  considerations 
  advanced 
  

   by 
  Saha. 
  He 
  points 
  out 
  that 
  within 
  the 
  range 
  of 
  temperatures 
  and 
  

   pressures 
  (hardly 
  less 
  important 
  than 
  temperatures) 
  prevailing 
  in 
  

   the 
  gases 
  at 
  the 
  surface 
  of 
  a 
  given 
  star, 
  the 
  different 
  elements 
  will 
  be 
  

   ionized 
  in 
  different 
  degrees, 
  depending 
  on 
  their 
  characteristic 
  " 
  ioni- 
  

   zation 
  potentials," 
  some 
  of 
  which 
  have 
  been 
  measured 
  in 
  the 
  labora- 
  

   tory. 
  Also 
  that 
  the 
  numbers 
  of 
  neutral 
  atoms, 
  atoms 
  less 
  one 
  

   electron, 
  atoms 
  less 
  two 
  electrons, 
  etc., 
  are 
  (in 
  principle 
  at 
  least, 
  if 
  

   not 
  yet 
  in 
  actual 
  fact) 
  calculable 
  thermodj^namically 
  from 
  energy 
  

   considerations 
  connected 
  with 
  the 
  ionization 
  potentials, 
  the 
  tempera- 
  

   tures 
  and 
  the 
  pressures 
  prevailing. 
  Proceeding 
  to 
  illustrate 
  with 
  

   assumed 
  numbers 
  for 
  the 
  element 
  calcium, 
  he 
  shows 
  that 
  as 
  between 
  

   temperatures 
  of 
  2,000° 
  and 
  4.000°, 
  absolute 
  centigrade, 
  the 
  relative 
  

   strength 
  of 
  lines 
  corresponding 
  respectively 
  to 
  neutral, 
  once-shorn, 
  

   and 
  twice-shorn 
  atoms 
  must 
  have 
  altered 
  immensely 
  in 
  favor 
  of 
  the 
  

   latter, 
  and 
  so 
  at 
  the 
  higher 
  temperature 
  the 
  line 
  spectrum 
  of 
  calcium 
  

   will 
  have 
  gone 
  over 
  predominantly 
  into 
  a 
  region 
  of 
  shorter 
  wave 
  

   lengths. 
  Moreover, 
  as 
  the 
  permanent 
  gases, 
  hydrogen, 
  helium, 
  and 
  

   others, 
  have 
  greatly 
  higher 
  " 
  ionization 
  potentials 
  " 
  than 
  elements 
  like 
  

   sodium, 
  calcium, 
  and 
  others, 
  the 
  stimulation 
  will 
  at 
  first 
  pass 
  by 
  pref- 
  

   erence 
  to 
  the 
  easily 
  excitable 
  atoms 
  of 
  the 
  latter 
  in 
  cases 
  of 
  mixture 
  

   of 
  elements 
  like 
  that 
  prevailing 
  in 
  the 
  sun 
  and 
  stars. 
  But 
  as 
  the 
  

   easily 
  ionizable 
  elements 
  become 
  fully 
  ionized, 
  and, 
  with 
  the 
  loss 
  of 
  

   one 
  or 
  even 
  two 
  or 
  more 
  electrons, 
  become 
  greatly 
  more 
  difficultly 
  

   excitable, 
  the 
  stimulus 
  of 
  the 
  temperature 
  will 
  more 
  and 
  more 
  be 
  

   diverted 
  to 
  affect 
  difficultly 
  ionizable 
  gases 
  like 
  hydrogen 
  and 
  helium. 
  

  

  Hence, 
  from 
  two 
  directions 
  the 
  spectra 
  are 
  influenced 
  to 
  alter 
  as 
  the 
  

   star 
  temperature 
  waxes 
  greater. 
  First 
  the 
  dissociation 
  of 
  the 
  atoms 
  

   of 
  the 
  metals 
  tends 
  to 
  throw 
  the 
  intensity 
  of 
  metallic 
  spectra 
  more 
  

   and 
  more 
  into 
  the 
  ultraviolet 
  regions 
  which 
  lie 
  beyond 
  our 
  observa- 
  

   tion 
  owing 
  to 
  the 
  absorption 
  in 
  our 
  atmosphere. 
  Second, 
  the 
  in- 
  

   creased 
  difficulty 
  of 
  exciting 
  these 
  once-shorn 
  or 
  twice-shorn 
  metallic 
  

   atoms 
  throws 
  the 
  effects 
  of 
  the 
  temperature 
  stimuli 
  more 
  and 
  more 
  to 
  

   intensify 
  the 
  lines 
  of 
  the 
  difficultly 
  ionizable 
  hydrogen 
  and 
  helium. 
  

   Finally, 
  the 
  less 
  conspicuous 
  but 
  highly 
  significant 
  and 
  experimen- 
  

   tally 
  valuable 
  influences 
  of 
  changes 
  of 
  pressure 
  associated 
  with 
  the 
  

   march 
  of 
  stellar 
  evolution 
  find 
  equally 
  satisfactory 
  theoretical 
  ex- 
  

   planations. 
  All 
  of 
  this 
  is 
  wholly 
  in 
  accord 
  with 
  the 
  observations 
  of 
  

   55379—24 
  12 
  

  

  