﻿W. 
  P. 
  White 
  — 
  Specific 
  Heat 
  Determination. 
  59 
  

  

  nace 
  and 
  in 
  the 
  time 
  required 
  for 
  heating. 
  The 
  charges 
  

   used 
  in 
  the 
  present 
  work 
  took 
  hours 
  to 
  heat 
  ; 
  frequently 
  

   two 
  determinations 
  in 
  a 
  rather 
  long 
  day 
  was 
  the 
  best 
  

   that 
  could 
  be 
  done 
  with 
  maximum 
  precision. 
  The 
  fall 
  

   tube 
  also 
  may 
  make 
  for 
  a 
  further 
  economy 
  of 
  time. 
  

   With 
  that 
  in 
  use 
  it 
  would 
  often 
  be 
  possible 
  to 
  put 
  sev- 
  

   eral 
  charged 
  containers 
  in 
  the 
  furnace 
  at 
  once 
  and 
  drop 
  

   them 
  one 
  by 
  one. 
  This 
  could 
  be 
  done 
  wherever 
  the 
  fur- 
  

   nace 
  is 
  so 
  uniform 
  in 
  temperature 
  that 
  a 
  thermometer 
  

   beside 
  the 
  charge 
  is 
  sufficient. 
  

  

  It 
  is 
  clear 
  that 
  many 
  of 
  the 
  difficulties 
  just 
  discussed 
  

   are 
  avoided 
  by 
  dispensing 
  with 
  water 
  as 
  a 
  calorimetric 
  

   substance, 
  and 
  using 
  instead 
  a 
  block 
  of 
  copper, 
  as 
  has 
  

   been 
  done 
  by 
  Magnus 
  23 
  and 
  Bronsted. 
  24 
  This 
  method 
  

   seems 
  promising 
  even 
  for 
  highest 
  precision, 
  though 
  for 
  

   that 
  improvements 
  over 
  the 
  calorimeters 
  thus 
  far 
  used 
  

   seem 
  needed. 
  The 
  ^ 
  aneroid 
  is 
  especially 
  exacting 
  in 
  the 
  

   matter 
  of 
  jacket 
  temperature 
  control. 
  25 
  Another 
  draw- 
  

   back 
  is 
  the 
  greater 
  time 
  required 
  for 
  the 
  charge 
  to 
  give 
  

   up 
  its 
  heat 
  in 
  the 
  absence 
  of 
  water, 
  but 
  this 
  may 
  be 
  set 
  

   against 
  the 
  advantages, 
  and 
  is 
  no 
  disadvantage 
  at 
  all 
  for 
  

   charges 
  consisting 
  of 
  a 
  single 
  lump, 
  or 
  for 
  substances 
  

   which 
  may 
  not 
  be 
  exposed 
  to 
  air 
  or 
  water. 
  

  

  Summary 
  

  

  This 
  paper 
  deals 
  with 
  the 
  experimental 
  technique 
  of 
  

   specific 
  heat 
  determination 
  at 
  temperatures 
  up 
  to 
  1400° 
  

   by 
  the 
  "Method 
  of 
  Mixtures," 
  and 
  continues 
  some 
  

   earlier 
  presentations. 
  Modifications 
  in 
  furnaces 
  and 
  in 
  

   methods 
  of 
  transferring 
  to 
  the 
  calorimeter 
  are 
  described 
  

   in 
  detail. 
  The 
  variability 
  of 
  the 
  heat 
  losses 
  attending 
  

   the 
  dropping 
  of 
  hot 
  bodies 
  into 
  water 
  proved 
  to 
  be 
  sur- 
  

   prisingly 
  great; 
  the 
  prevention 
  of 
  such 
  losses 
  is 
  prob- 
  

   ably 
  advisable 
  in 
  accurate 
  work, 
  perhaps 
  by 
  the 
  use 
  of 
  

   aneroid 
  calorimeters. 
  

  

  Geophysical 
  Laboratory, 
  

  

  Carnegie 
  Institution 
  of 
  Washington, 
  

   June 
  28, 
  1918. 
  

  

  23 
  A. 
  Magnus, 
  Specifische 
  Warmen 
  Fester 
  Korper 
  bei 
  hohen 
  Temperaturen, 
  

   Physik. 
  Zs., 
  14, 
  5, 
  1913 
  ; 
  Die 
  spezifische 
  Warme 
  des 
  Platins 
  unci 
  des 
  Diaman- 
  

   ten 
  bei 
  hohen 
  Temperaturen, 
  Ann. 
  Phys., 
  48, 
  984, 
  1915. 
  

  

  24 
  J. 
  N. 
  Brousted, 
  Untersuchungen 
  iiber 
  die 
  specifische 
  Warme, 
  Zs. 
  Elek- 
  

   trochem., 
  18, 
  714, 
  1912. 
  

  

  25 
  Walter 
  P. 
  White, 
  Calorimetric 
  Methods 
  and 
  Devices, 
  J. 
  Am. 
  Chem. 
  Soc, 
  

   40, 
  1893, 
  1918. 
  

  

  