﻿208 
  Effect 
  of 
  Temperature 
  on 
  Production 
  of 
  Uranium 
  X, 
  

  

  throuorliout 
  the 
  globe, 
  is 
  more 
  than 
  sufficient 
  to 
  account 
  for 
  

   the 
  Earth^s 
  internal 
  heat. 
  I£ 
  the 
  rate 
  o£ 
  production 
  of 
  

   Uranium 
  X 
  from 
  uranium 
  is 
  retarded 
  at 
  high 
  temperatures 
  

   it 
  is 
  possible 
  that 
  the 
  subsequent 
  transformation 
  products, 
  

   including 
  radium, 
  may 
  exist 
  in 
  relatively 
  smaller 
  quantities 
  

   in 
  the 
  hotter 
  strata 
  beneath 
  the 
  cooler 
  crust. 
  Experiments 
  

   have 
  been 
  performed 
  on 
  the 
  rate 
  of 
  production 
  of 
  Uranium 
  X 
  

   in 
  specimens 
  kept 
  respectively 
  at 
  atmospheric 
  temperatures 
  

   and 
  at 
  1000° 
  C. 
  

  

  To 
  prepare 
  a 
  salt 
  of 
  uranium 
  ag 
  free 
  as 
  possible 
  from 
  

   Uranium 
  X, 
  the 
  method 
  described 
  b}^ 
  Sir 
  William 
  Crookes 
  

   (Proc. 
  Roy. 
  Soc. 
  Ixvi. 
  1900) 
  was 
  employed. 
  Uranium 
  nitrate 
  

   was 
  dissolved 
  in 
  ether 
  in 
  a 
  separating 
  funnel, 
  and 
  a 
  little 
  

   freshly 
  precipitated 
  ferric 
  hydrate 
  was 
  added. 
  The 
  ethereal 
  

   portion 
  of 
  the 
  solution 
  was 
  separated 
  from 
  the 
  aqueous 
  part, 
  

   containing 
  the 
  bulk 
  of 
  the 
  Uranium 
  X, 
  and 
  allowed 
  to 
  

   evaporate 
  to 
  dryness. 
  The 
  residue 
  was 
  treated 
  in 
  a 
  similar 
  

   manner, 
  and 
  after 
  three 
  successive 
  separations 
  a 
  salt 
  was 
  

   obtained 
  containing 
  an 
  amount 
  of 
  Uranium 
  X 
  which 
  would 
  

   be 
  produced 
  in 
  a 
  day 
  from 
  the 
  inactive 
  uranium 
  salt. 
  The 
  

   nitrate 
  was 
  then 
  ignited 
  and 
  the 
  resulting 
  oxide 
  thoroughly 
  

   well 
  mixed 
  and 
  divided 
  into 
  two 
  equal 
  portions. 
  These 
  were 
  

   -enclosed 
  in 
  quartz 
  tubes, 
  one 
  being 
  kept 
  at 
  the 
  temperature 
  

   of 
  the 
  laboratory 
  and 
  the 
  other 
  heated 
  in 
  a 
  gas 
  muffle-furnace 
  

   to 
  a 
  temperature 
  of 
  1000° 
  C. 
  The 
  rate 
  of 
  formation 
  of 
  

   Uranium 
  X 
  was 
  studied 
  by 
  measuring 
  the 
  yS-ray 
  activity 
  as 
  

   evidenced 
  by 
  the 
  rate 
  at 
  which 
  the 
  specimens 
  discharged 
  a 
  

   gold-leaf 
  electroscope. 
  The 
  normal 
  leak 
  of 
  the 
  electroscope 
  

   was 
  determined 
  several 
  times 
  throughout 
  the 
  investigation, 
  

   and 
  varied 
  from 
  4*3 
  to 
  5*0 
  scale-divisions 
  per 
  hour 
  over 
  the 
  

   range 
  used 
  in 
  the 
  experiments. 
  

  

  In 
  making 
  an 
  experiment 
  the 
  cold 
  specimen 
  was 
  placed 
  in 
  

   a 
  definite 
  position 
  above 
  the 
  electroscope, 
  and 
  the 
  time 
  taken 
  

   for 
  the 
  gold-leaf 
  to 
  move 
  over 
  a 
  fixed 
  part 
  of 
  the 
  eyepiece 
  

   scale 
  of 
  the 
  observing 
  microscope 
  was 
  recorded. 
  The 
  cold 
  

   specimen 
  was 
  then 
  replaced 
  by 
  the 
  one 
  which 
  had 
  been 
  

   heated, 
  and 
  a 
  similar 
  observation 
  was 
  made. 
  In 
  no 
  case 
  was 
  

   the 
  hot 
  specimen 
  out 
  of 
  the 
  furnace 
  for 
  more 
  than 
  two 
  hours 
  

   for 
  any 
  observation. 
  Making 
  suitable 
  allowance 
  for 
  the 
  

   normal 
  leak 
  of 
  the 
  instrument, 
  the 
  rate 
  of 
  leak 
  in 
  scale- 
  

   divisions 
  per 
  hour 
  for 
  each 
  of 
  the 
  specimens 
  was 
  calculated 
  

   and 
  the 
  ratio 
  between 
  them 
  determined. 
  The 
  variation 
  of 
  

   this 
  ratio 
  with 
  time 
  served 
  as 
  an 
  index 
  of 
  the 
  rates 
  of 
  growth 
  

   in 
  the 
  specimens. 
  

  

  The 
  following 
  details 
  of 
  one 
  of 
  the 
  experiments 
  may 
  be 
  

   taken 
  as 
  typical 
  of 
  others 
  obtained. 
  

  

  