﻿6 
  W. 
  P. 
  White 
  — 
  Silicate 
  Specific 
  Heats. 
  

  

  tube 
  4 
  mm. 
  in 
  diameter. 
  This 
  rather 
  tightly 
  fitting 
  ther- 
  

   moelement 
  was 
  withdrawn 
  just 
  before 
  the 
  drop 
  of 
  the 
  

   charge, 
  so 
  as 
  not 
  to 
  interfere 
  with 
  a 
  free 
  fall. 
  The 
  plati- 
  

   num 
  tube 
  was, 
  of 
  course, 
  part 
  of 
  the 
  container. 
  

  

  The 
  effectiveness 
  of 
  these 
  arrangements 
  for 
  tempera- 
  

   ture 
  uniformity 
  was 
  tested 
  in 
  several 
  different 
  ways 
  at 
  

   different 
  times, 
  by 
  observations 
  which, 
  all 
  told, 
  extended 
  

   over 
  several 
  weeks. 
  Thermoelements, 
  3 
  or 
  4 
  in 
  number, 
  

   were 
  welded 
  to 
  the 
  platinum 
  container 
  or 
  placed 
  in 
  dif- 
  

   ferent 
  parts 
  of 
  the 
  charge 
  and 
  finally, 
  at 
  the 
  close 
  of 
  the 
  

   work, 
  4 
  junctions 
  of 
  very 
  fine 
  wire 
  (0-2 
  mm.) 
  connected 
  in 
  

   parallel 
  were 
  distributed 
  through 
  the 
  charge 
  so 
  as 
  to 
  give 
  

   its 
  mean 
  temperature, 
  and 
  this, 
  in 
  3 
  different 
  charges, 
  was 
  

   compared 
  with 
  the 
  temperature 
  read 
  by 
  the 
  charge 
  ele- 
  

   ment 
  in 
  the 
  central 
  tube. 
  The 
  results 
  were: 
  The 
  max- 
  

   imum 
  difference 
  of 
  temperature 
  observed 
  was 
  3-3° 
  over 
  

   the 
  platinum 
  container 
  and 
  2° 
  within 
  the 
  charge, 
  but 
  the 
  

   mean 
  temperature 
  of 
  the 
  charge 
  differed 
  scarcely 
  0-2° 
  

   from 
  the 
  thermoelement 
  in 
  the 
  small 
  tube. 
  These 
  vari- 
  

   ous 
  tests 
  are 
  not 
  inconsistent 
  with 
  each 
  other, 
  and 
  seem 
  to 
  

   indicate 
  that 
  the 
  problem 
  of 
  determining 
  the 
  charge 
  

   temperature, 
  the 
  most 
  critical 
  in 
  this 
  work, 
  was 
  satisfac- 
  

   torily 
  solved, 
  even 
  without 
  the 
  complication 
  of 
  extra 
  

   furnace 
  coils. 
  The 
  results 
  given 
  in 
  Table 
  I 
  of 
  the 
  follow- 
  

   ing 
  paper 
  and 
  those 
  in 
  Table 
  X 
  of 
  this 
  paper 
  tend 
  to 
  

   confirm 
  this 
  conclusion. 
  

  

  In 
  the 
  lead-bath 
  and 
  steam 
  heaters, 
  used 
  below 
  700°, 
  

   the 
  temperature 
  was 
  very 
  uniform, 
  7 
  and 
  the 
  problem 
  of 
  

   knowing 
  the 
  charge 
  temperature 
  was 
  far 
  easier. 
  It 
  was 
  

   possible 
  here 
  to 
  have 
  the 
  thermoelement 
  outside 
  the 
  

   charge, 
  which 
  simplified 
  manipulations 
  considerably. 
  It 
  

   was 
  then 
  only 
  necessary 
  to 
  be 
  sure 
  that 
  the 
  heating 
  was 
  

   continued 
  long 
  enough. 
  The 
  method 
  used 
  to 
  test 
  this 
  

   point 
  was 
  simply 
  to 
  have 
  a 
  thermo-couple 
  read 
  the 
  dif- 
  

   ference 
  between 
  the 
  center 
  of 
  the 
  charge 
  and 
  the 
  furnace 
  

   cavity 
  outside 
  it, 
  and 
  thus 
  ascertain 
  the 
  time 
  necessary 
  

   to 
  bring 
  the 
  whole 
  of 
  that 
  particular 
  charge 
  to 
  the 
  fur- 
  

   nace 
  temperature. 
  

  

  Normal 
  results 
  with 
  the 
  metal-bath 
  furnace 
  are 
  doubt- 
  

   loss 
  still 
  less 
  affected 
  bv 
  svstematic 
  error 
  than 
  those 
  at 
  

   higher 
  temperatures. 
  Owing, 
  however, 
  to 
  several 
  acci- 
  

   dental 
  circumstances, 
  treated 
  in 
  the 
  following 
  paper, 
  some 
  

   of 
  the 
  results 
  obtained 
  with 
  this 
  furnace 
  are 
  not 
  certain 
  to 
  

  

  7 
  For 
  a 
  discussion 
  of 
  this 
  point 
  see 
  the 
  following 
  paper. 
  

  

  

  