﻿High 
  Temperatures. 
  

  

  183 
  

  

  Bulb 
  freshly 
  filled. 
  Ho 
  

  

  a 
  

  

  t 
  

  

  Ci 
  

  

  Obs.-Calcul. 
  

  

  1st 
  day 
  

  

  412-66 
  

  

  0-003673 
  

  

  

  

  

  2d 
  " 
  

  

  

  

  803-2 
  

  

  7123 
  

  

  + 
  0-7 
  

  

  

  

  

  891-8 
  

  

  8094 
  

  

  — 
  0-3 
  

  

  

  

  

  1003-9 
  

  

  9311 
  

  

  + 
  2-6 
  

  

  

  

  

  1099-6 
  

  

  10400 
  

  

  + 
  2-6 
  

  

  

  

  

  1161-5 
  

  

  11128 
  

  

  + 
  1-2 
  

  

  

  

  

  1113-6 
  

  

  10574 
  

  

  + 
  1-4 
  

  

  

  

  

  1029-5 
  

  

  9616 
  

  

  + 
  1-2 
  

  

  3d 
  " 
  

  

  413-96 
  

  

  0-003671 
  

  

  

  

  

  4th 
  " 
  

  

  

  

  793-8 
  

  

  7043 
  

  

  -1-2 
  

  

  

  

  

  901-6 
  

  

  8200 
  

  

  -0-2 
  

  

  

  

  

  9994 
  

  

  9292 
  

  

  -0-5 
  

  

  

  

  

  1107-4 
  

  

  10517 
  

  

  + 
  0-2 
  

  

  

  

  

  1049-2 
  

  

  9844 
  

  

  + 
  0-9 
  

  

  

  

  

  938-1 
  

  

  8591 
  

  

  + 
  1-0 
  

  

  

  

  

  847-8 
  

  

  7610 
  

  

  0-0 
  

  

  5th 
  " 
  

  

  413-99 
  

  

  0-0036755 
  

  

  

  

  

  6th 
  '' 
  

  

  413-90 
  

  

  0-003674 
  

  

  

  

  

  8th 
  '^ 
  

  

  413-97 
  

  

  

  

  

  

  In 
  order 
  to 
  be 
  sure 
  that 
  the 
  apparatus 
  had 
  remained 
  air-tight, 
  

   at 
  the 
  close 
  of 
  the 
  observations 
  several 
  ice 
  points 
  were 
  taken 
  

   on 
  different 
  days. 
  These 
  agree 
  within 
  the 
  limits 
  of 
  the 
  error 
  

   of 
  observation. 
  The 
  mean 
  difference 
  between 
  observed 
  and 
  

   calculated 
  values 
  of 
  ^ 
  = 
  d= 
  1*52°. 
  

  

  5. 
  Experiments 
  with 
  bulbs 
  glazed 
  outside 
  only. 
  

  

  The 
  experiments 
  with 
  bulbs 
  left 
  unglazed 
  on 
  the 
  inside 
  did 
  

   not 
  differ 
  materially 
  from 
  the 
  preceding. 
  The 
  heating 
  was 
  all 
  

   done 
  in 
  the 
  electric 
  oven. 
  The 
  old 
  manometer 
  was 
  still 
  used 
  

   for 
  the 
  pressure 
  measurements, 
  but 
  the 
  unheated 
  space 
  was 
  

   still 
  further 
  diminished 
  by 
  the 
  use 
  of 
  a 
  metallic 
  cap 
  for 
  closing 
  

   the 
  short 
  tube 
  of 
  the 
  manometer 
  at 
  the 
  top 
  so 
  that 
  the 
  correc- 
  

   tion 
  at 
  500° 
  amounted 
  to 
  only 
  4-7 
  per 
  cent, 
  at 
  1000° 
  to 
  T-2 
  

   per 
  cent, 
  and 
  at 
  1100° 
  to 
  T'8 
  per 
  cent 
  of 
  t. 
  

  

  The 
  gas 
  pressure 
  was 
  chosen 
  considerably 
  smaller 
  than 
  

   before, 
  because 
  the 
  bulbs 
  were 
  to 
  be 
  heated 
  above 
  the 
  melting 
  

   point 
  of 
  the 
  glazing 
  ; 
  it 
  was 
  therefore 
  necessary 
  that 
  the 
  

   maximum 
  pressure 
  reached 
  should 
  not 
  exceed 
  the 
  atmospheric 
  

   pressure. 
  The 
  melted 
  glazing, 
  being 
  thus 
  continually 
  pressed 
  

   into 
  the 
  pores 
  of 
  the 
  porcelain, 
  held 
  tight. 
  Only 
  a 
  slight 
  

   excess 
  of 
  pressure 
  inside 
  at 
  this 
  temperature 
  suffices 
  for 
  the 
  gas 
  

   to 
  filter 
  through 
  and 
  escape. 
  

  

  Considerable 
  difficulties 
  were 
  liere 
  experienced 
  from 
  the 
  

   sticking 
  of 
  the 
  melted 
  glazing 
  to 
  the 
  oven 
  wall 
  if 
  the 
  slightest 
  

   contact 
  occurred, 
  in 
  which 
  case 
  it 
  was 
  almost 
  impossible 
  to 
  

   remove 
  the 
  bulb 
  after 
  cooling 
  without 
  cracking 
  the 
  glaze. 
  It 
  

   would 
  then 
  be 
  no 
  longer 
  air-tight, 
  nor 
  in 
  fact 
  of 
  any 
  further 
  

  

  