﻿High 
  Temperatures. 
  ITl 
  

  

  The 
  platinum 
  capillary 
  tube 
  serving 
  to 
  connect 
  the 
  bulb 
  

   with 
  the 
  manotneter 
  was 
  soldered 
  at 
  one 
  end 
  into 
  the 
  metallic 
  

   cap 
  before 
  mentioned 
  and 
  at 
  the 
  other 
  attached 
  to 
  the 
  stem 
  of 
  

   the 
  bulb 
  with 
  sealing 
  wax, 
  this 
  arrangement 
  proving 
  quite 
  as 
  

   trustworthy 
  and 
  convenient 
  as 
  a 
  soldered 
  joint. 
  The 
  sealing 
  

   wax 
  could 
  be 
  kept 
  cool 
  with 
  water 
  if 
  necessary. 
  The 
  length 
  

   of 
  the 
  capillary 
  tube 
  was 
  much 
  reduced 
  in 
  the 
  new 
  instrument 
  

   (from 
  1'3T™ 
  to 
  0'S5™), 
  an 
  improvement 
  rendered 
  possible 
  by 
  the 
  

   electrical 
  oven, 
  which 
  could 
  of 
  course 
  be 
  much 
  better 
  protected 
  

   from 
  radiation 
  than 
  a 
  gas 
  heater. 
  Under 
  the 
  new 
  arrangement 
  

   a 
  glass 
  partition 
  was 
  amply 
  sufficient 
  to 
  separate 
  oven 
  and 
  

   manometer, 
  a 
  service 
  for 
  which 
  before 
  a 
  brick 
  wall 
  had 
  been 
  

   deemed 
  necessary. 
  That 
  the 
  gas 
  pressure 
  in 
  bulb 
  and 
  mano- 
  

   meter 
  may 
  come 
  quickly 
  to 
  a 
  condition 
  of 
  equilibrium, 
  the 
  

   capillary 
  tube 
  should 
  not 
  be 
  chosen 
  less 
  than 
  two-thirds 
  of 
  a 
  

   millimeter 
  in 
  diameter. 
  

  

  This 
  flexible 
  capillary 
  also 
  enabled 
  us 
  to 
  move 
  the 
  thermo- 
  

   meter 
  bulb 
  about 
  at 
  will 
  for 
  determining 
  ice 
  and 
  boiling 
  points 
  

   after 
  each 
  heating 
  ; 
  we 
  found 
  it, 
  however, 
  better 
  to 
  move 
  it 
  as 
  

   little 
  as 
  possible, 
  and 
  in 
  our 
  later 
  experiments 
  the 
  oven 
  was 
  

   mounted 
  upon 
  a 
  framework 
  provided 
  with 
  wheels 
  and 
  moving 
  

   upon 
  a 
  track 
  which 
  enabled 
  it 
  to 
  be 
  pushed 
  aside 
  when 
  the 
  

   bulb 
  was 
  taken 
  out, 
  and 
  ice 
  and 
  boiling 
  point 
  observations 
  to 
  

   be 
  made 
  at 
  the 
  same 
  point 
  by 
  appropriately 
  constructed 
  ap- 
  

   paratus. 
  By 
  this 
  arrangement 
  the 
  amount 
  of 
  bending 
  of 
  the 
  

   capillary 
  required 
  was 
  very 
  small. 
  

  

  Ice 
  and 
  boiling 
  point 
  observations 
  were 
  made 
  after 
  each 
  

   heating 
  during 
  these 
  experiments, 
  not 
  so 
  much 
  for 
  their 
  value 
  

   as 
  constants 
  of 
  the 
  instrument 
  and 
  for 
  the 
  temperature 
  deter- 
  

   mination 
  as 
  to 
  determine 
  any 
  change 
  which 
  the 
  measuring 
  gas 
  

   might 
  have 
  undergone 
  at 
  the 
  higher 
  temperatures. 
  

  

  The 
  temperature 
  as 
  observed 
  with 
  the 
  air 
  thermometer 
  was 
  

   calculated 
  according 
  to 
  the 
  following 
  formula 
  : 
  

  

  IT 
  /, 
  ^ 
  1 
  \ 
  H 
  / 
  ^ 
  V 
  l-\-at 
  \ 
  

  

  M'+f 
  iTot) 
  = 
  rr^jO^-^'^'^ 
  v;-TT<) 
  

  

  where 
  

  

  H^ 
  — 
  Pressure 
  at 
  0°. 
  

  

  Y^ 
  = 
  Volume 
  of 
  bulb 
  at 
  0". 
  

  

  «, 
  — 
  " 
  '' 
  " 
  unheated 
  space" 
  at 
  the 
  temperature 
  of 
  the 
  

  

  room. 
  (Changes 
  in 
  volume 
  i\ 
  due 
  to 
  temperature 
  neglected.) 
  

  

  t^ 
  and 
  tl=z 
  temperatures 
  of 
  '' 
  unheated 
  space 
  " 
  with 
  bulb 
  in 
  ice 
  

   and 
  at 
  temperature 
  t. 
  

  

  a 
  = 
  coefficient 
  of 
  expansion 
  (technically 
  pressure 
  coefficient 
  or 
  

   coefficient 
  of 
  expansion 
  at 
  constant 
  volume) 
  of 
  the 
  gas 
  between 
  

   0° 
  and 
  100° 
  (determined 
  after 
  each 
  heating). 
  

  

  3^= 
  cubical 
  coefficient 
  of 
  expansion 
  of 
  the 
  bulb. 
  

  

  