﻿44 
  W. 
  P. 
  White 
  — 
  Specific 
  Heat 
  Determination. 
  

  

  Art. 
  II. 
  — 
  Specific 
  Heat 
  Determination 
  at 
  Higher 
  Tem- 
  

   peratures; 
  by 
  Walter 
  P. 
  White. 
  

  

  This 
  paper 
  deals 
  with 
  some 
  experimental 
  details 
  of 
  

   the 
  work 
  described 
  in 
  the 
  paper 
  immediately 
  preceding, 
  

   and 
  the 
  two 
  are 
  presented 
  separately 
  mainly 
  because 
  

   they 
  may 
  tend 
  to 
  interest 
  different 
  classes 
  of 
  readers. 
  

   The 
  general 
  methods 
  used 
  are 
  described 
  very 
  briefly 
  

   at 
  the 
  beginning 
  of 
  the 
  preceding 
  paper, 
  and 
  in 
  more 
  

   detail 
  in 
  some 
  earlier 
  papers 
  ; 
  x 
  the 
  present 
  material 
  is 
  

   essentially 
  a 
  report 
  of 
  further 
  experience 
  or 
  progress. 
  

  

  The 
  experimental 
  procedure 
  presents 
  three 
  features, 
  

   the 
  heating 
  of 
  the 
  body 
  and 
  determination 
  of 
  its 
  temper- 
  

   ature 
  ; 
  the 
  transfer 
  to 
  the 
  calorimeter 
  ; 
  the 
  measurement 
  

   of 
  the 
  heat 
  in 
  the 
  calorimeter. 
  The 
  temperature 
  deter- 
  

   mination 
  in 
  the 
  furnace, 
  inherently 
  the 
  most 
  difficult 
  of 
  

   the 
  three, 
  appears, 
  as 
  already 
  said, 
  to 
  have 
  been 
  entirely 
  

   satisfactory. 
  The 
  calorimetric 
  precision 
  was 
  consid- 
  

   erably 
  in 
  excess 
  of 
  requirements. 
  The 
  transfer, 
  while 
  

   far 
  from 
  being 
  positively 
  a 
  failure, 
  was, 
  by 
  comparison, 
  

   the 
  weakest 
  link 
  in 
  the 
  chain 
  of 
  operations. 
  

  

  I. 
  Furnace 
  Temperature. 
  

  

  1. 
  Platinum-wound 
  furnace. 
  — 
  In 
  an 
  earlier 
  report 
  2 
  it 
  

   was 
  stated 
  that 
  the 
  uniformity 
  of 
  furnace 
  temperature 
  

   increased 
  as 
  the 
  temperature 
  became 
  higher. 
  It 
  has 
  

   since 
  been 
  found 
  that 
  this 
  result 
  was 
  exceptional 
  and 
  

   therefore 
  misleading. 
  Two 
  effects 
  were 
  at 
  work; 
  first, 
  

   a 
  tendency, 
  apparently 
  characteristic 
  of 
  the 
  type 
  of 
  

   platinum-wound 
  furnace 
  used, 
  for 
  the 
  top 
  to 
  be 
  colder 
  

   than 
  the 
  bottom 
  at 
  higher 
  temperatures, 
  and 
  second, 
  a 
  

   cooling 
  of 
  the 
  bottom 
  by 
  a 
  slight 
  upward 
  current 
  of 
  air 
  

   through 
  the 
  furnace. 
  These 
  happened 
  to 
  neutralize 
  each 
  

   other 
  at 
  the 
  higher 
  temperatures 
  observed. 
  The 
  con- 
  

   siderable 
  effect 
  produced 
  (15° 
  difference 
  over 
  6 
  cm. 
  in 
  the 
  

   middle 
  of 
  the 
  furnace 
  at 
  500°) 
  by 
  a 
  slight 
  air-current 
  

  

  1 
  Especially 
  in 
  : 
  Walter 
  P. 
  White, 
  Specific 
  Heats 
  of 
  Silicates 
  and 
  Platinum, 
  

   this 
  Journal, 
  28, 
  334, 
  1909; 
  Some 
  Calorimetric 
  Apparatus, 
  Phys. 
  Rev., 
  31, 
  

   671, 
  1910; 
  Easy 
  Calorimetric 
  Methods 
  of 
  High 
  Precision, 
  J. 
  Am. 
  Chem. 
  

   Soc, 
  36, 
  2313, 
  1914. 
  

  

  2 
  Specific 
  Heats, 
  etc., 
  loc. 
  cit., 
  page 
  335. 
  

  

  