﻿Effect 
  of 
  Temperature 
  on 
  Production 
  of 
  Uranium 
  X. 
  207 
  

  

  ordinary 
  method 
  perpendicular 
  to 
  the 
  axis 
  of 
  the 
  instrument. 
  

   The 
  telescope 
  is 
  turned 
  to 
  one 
  side, 
  and 
  a 
  telescope 
  with 
  a 
  

   Savart^s 
  analyser 
  is 
  inserted 
  in 
  its 
  place 
  with 
  its 
  axis 
  in 
  

   the 
  direction 
  of 
  that 
  of 
  the 
  collimator, 
  and 
  the 
  analyser 
  is 
  

   adjusted 
  so 
  that, 
  when 
  plane 
  polarized 
  light 
  passes, 
  the 
  

   fringes 
  are 
  parallel 
  to 
  the 
  web 
  of 
  the 
  collimator. 
  This 
  setj> 
  

   the 
  plane 
  bisecting 
  the 
  angle 
  between 
  the 
  principal 
  sections 
  

   of 
  the 
  plates 
  of 
  the 
  analyser 
  perpendicular 
  to 
  the 
  turning- 
  

   axis 
  of 
  the 
  spectrometer. 
  This 
  adjustment 
  being 
  made, 
  the 
  

   polarizer 
  is 
  turned 
  until 
  the 
  fringes 
  disappear 
  exactly 
  in 
  the- 
  

   centre 
  of 
  the 
  field. 
  

  

  The 
  quartz 
  plate 
  is 
  then 
  placed 
  at 
  the 
  centre 
  of 
  the 
  table 
  

   of 
  the 
  instrument, 
  and 
  by 
  means 
  of 
  the 
  telescope 
  of 
  the 
  spec- 
  

   trometer 
  its 
  faces 
  are 
  made 
  parallel 
  to 
  the 
  turning 
  axis, 
  and 
  

   the 
  readino- 
  determined 
  for 
  which 
  its 
  normal 
  is 
  alono- 
  the 
  

   axis 
  of 
  the 
  collimator. 
  

  

  With 
  the 
  polarizer 
  adjusted 
  as 
  above, 
  the 
  fringes 
  will 
  in 
  

   general 
  be 
  restored 
  when 
  the 
  light 
  traverses 
  the 
  quartz, 
  but 
  

   a 
  series 
  of 
  positions 
  can 
  be 
  found 
  for 
  which 
  they 
  vanish 
  over 
  

   a 
  narrow 
  streak 
  extending 
  across 
  the 
  field, 
  and 
  if 
  the 
  quartz, 
  

   plate 
  be 
  turned 
  about 
  its 
  normal 
  so 
  as 
  to 
  bring 
  its 
  optic 
  axis 
  

   perpendicular 
  to 
  the 
  turning 
  axis 
  of 
  the 
  spectrometer, 
  there^ 
  

   will 
  be, 
  intermediate 
  to 
  these, 
  further 
  positions 
  at 
  which 
  

   the 
  fringes 
  are 
  absent 
  over 
  a 
  small 
  area 
  at 
  the 
  centre 
  of 
  the 
  

   field. 
  

  

  In 
  this 
  way 
  the 
  principal 
  section 
  of 
  the 
  quartz 
  is 
  set 
  per- 
  

   pendicular 
  to 
  the 
  turning 
  axis 
  of 
  the 
  instrument, 
  and 
  a, 
  

   determination 
  of 
  the 
  angles 
  of 
  incidence, 
  for 
  which 
  the 
  

   centres 
  of 
  the 
  zones 
  of 
  disappearance 
  of 
  the 
  fringes 
  are 
  at 
  

   the 
  centre 
  of 
  the 
  field, 
  will 
  give 
  by 
  calculation 
  or 
  by 
  the 
  

   graphic 
  method 
  employed 
  by 
  Beaulard 
  * 
  the 
  direction 
  of 
  

   the 
  optic 
  axis 
  with 
  respect 
  to 
  the 
  faces 
  of 
  the 
  quartz. 
  

  

  XXII 
  r. 
  The 
  Effect 
  of 
  Temperature 
  on 
  the 
  Bate 
  of 
  Production 
  

   of 
  Uranium 
  X. 
  By 
  R. 
  W. 
  FoRsriH, 
  A.R.C.Sc, 
  Imperial 
  

   College 
  of 
  Science 
  and 
  Technology 
  f. 
  

  

  IN 
  the 
  following 
  paper 
  an 
  account 
  is 
  given 
  of 
  experiments 
  

   carried 
  out 
  to 
  determine 
  whether 
  the 
  rate 
  of 
  production 
  

   of 
  Uranium 
  X 
  from 
  a 
  salt 
  of 
  uranium 
  depends 
  upon 
  the 
  

   temperature 
  of 
  the 
  compound 
  in 
  which 
  the 
  transformation 
  is 
  

   taking 
  place. 
  Calculations 
  have 
  shown 
  that 
  the 
  quantity 
  of 
  

   radium 
  present 
  in 
  the 
  crust 
  of 
  the 
  Earth, 
  if 
  evenly 
  distributed 
  

  

  * 
  These 
  de 
  Dodorat, 
  Marseille, 
  1893. 
  

  

  t 
  Communicated 
  by 
  Prof, 
  the 
  Hon. 
  E. 
  J. 
  Strutt; 
  F.K.S. 
  

  

  