﻿Mean 
  Annual 
  Temperature 
  Variation. 
  409 
  

  

  mean 
  atmospheric 
  pressure 
  at 
  the 
  South 
  Orkneys, 
  for 
  each 
  day 
  

   of 
  the 
  year, 
  bears 
  a 
  close 
  resemblance 
  to 
  that 
  of 
  Edinburgh. 
  

  

  Forcibly, 
  therefore, 
  we 
  reach 
  the 
  conclusion 
  that 
  in 
  a 
  com- 
  

   parative 
  study 
  of 
  the 
  anomalies 
  of 
  the 
  annual 
  temperature 
  

   variation, 
  Teisserenc 
  de 
  Bort's 
  conception 
  of 
  the 
  great 
  centers 
  

   of 
  action 
  of 
  atmospheric 
  circulation 
  will 
  find 
  an 
  extensive 
  

   application 
  ; 
  because, 
  although 
  at 
  present 
  it 
  would 
  be 
  prema- 
  

   ture 
  to 
  try 
  to 
  explain 
  why 
  it 
  is 
  that 
  some 
  changes 
  of 
  phase 
  

   may 
  occur 
  simultaneously 
  in 
  Arctic 
  and 
  Antarctic 
  regions, 
  or 
  in 
  

   North 
  America 
  and 
  Siberia, 
  it 
  seems 
  impossible 
  to 
  conceive 
  

   such 
  correlations 
  without 
  supposing 
  some 
  relationship 
  with 
  the 
  

   exchange 
  of 
  pressure 
  between 
  the 
  seasonal 
  and 
  permanent 
  cen- 
  

   ters 
  of 
  action. 
  

  

  New 
  York 
  City, 
  

   November 
  2, 
  1916. 
  

  

  SCIENTIFIC 
  INTELLIGENCE. 
  

  

  I. 
  Chemistry 
  and 
  Physics. 
  

  

  1. 
  Attempt 
  to 
  Separate 
  the 
  Izotopic 
  Forms 
  of 
  Lead 
  by 
  Frac- 
  

   tional 
  Recrystallization. 
  — 
  Although 
  the 
  complete 
  inseparability 
  

   of 
  isotopes 
  by 
  chemical 
  means 
  has 
  been 
  frequently 
  asserted, 
  

   Theodore 
  W. 
  Richards 
  and 
  Norris 
  F. 
  Hall 
  have 
  deemed 
  it 
  

   desirable 
  to 
  test 
  the 
  possibility 
  of 
  such 
  a 
  separation 
  still 
  further 
  

   and 
  they 
  have 
  made 
  a 
  very 
  elaborate 
  attempt 
  to 
  do 
  this 
  with 
  the 
  

   radioactive 
  lead 
  from 
  Australian 
  carnotite. 
  The 
  low 
  atomic 
  

   weight 
  of 
  this 
  sample 
  of 
  lead, 
  previously 
  determined 
  by 
  Richards 
  

   and 
  Wadsworth, 
  indicated 
  that 
  it 
  contained 
  three 
  or 
  four 
  parts 
  of 
  

   the 
  isotope 
  (usually 
  assumed 
  to 
  be 
  radium 
  G-) 
  to 
  one 
  of 
  lead, 
  and 
  

   its 
  /3-ray 
  activity 
  showed 
  that 
  it 
  contained 
  sufficient 
  radium 
  D 
  to 
  

   serve 
  as 
  a 
  basis 
  for 
  testing 
  the 
  possible 
  separation 
  of 
  this 
  isotope 
  

   from 
  the 
  inactive 
  varieties. 
  About 
  1 
  kilogram 
  of 
  this 
  radioactive 
  

   lead 
  was 
  converted 
  into 
  the 
  nitrate, 
  and 
  this 
  salt 
  was 
  subjected 
  

   to 
  systematic 
  fractional 
  crystallization 
  by 
  cooling 
  the 
  boiling, 
  

   nearly 
  saturated 
  aqueous 
  solutions, 
  and 
  carrying 
  the 
  crystals 
  and 
  

   mother 
  liquors 
  in 
  opposite 
  directions 
  in 
  the 
  series. 
  About 
  1000 
  

   separate 
  crystallizations 
  were 
  thus 
  made, 
  where 
  the 
  end-products 
  

   were 
  combined 
  when 
  they 
  became 
  too 
  small 
  for 
  convenient 
  work, 
  

   and 
  a 
  series 
  of 
  18 
  members 
  was 
  finally 
  obtained. 
  Four 
  of 
  these 
  

   members 
  at 
  the 
  " 
  more 
  soluble" 
  end 
  and 
  six 
  at 
  the 
  " 
  less 
  soluble 
  " 
  

   end 
  were 
  united 
  in 
  each 
  case, 
  and 
  these 
  products 
  were 
  carefully 
  

   purified, 
  converted 
  into 
  chloride, 
  and 
  subjected 
  to 
  atomic 
  weight 
  

  

  