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  Allen 
  and 
  Lombard 
  — 
  Determination 
  of 
  

  

  bulbs 
  A 
  and 
  C 
  (see 
  fig. 
  1) 
  shall 
  be 
  lower 
  than 
  the 
  temperature 
  

   of 
  bulb 
  A 
  containing 
  the 
  sulphur. 
  The 
  furnace 
  ends 
  must 
  of 
  

   course 
  lit 
  well 
  together 
  or 
  a 
  cold 
  region 
  will 
  be 
  found 
  at 
  the 
  

   joint. 
  

  

  Calibration 
  of 
  thermocouples. 
  — 
  All 
  the 
  thermocouples 
  used 
  

   in 
  these 
  experiments 
  were 
  of 
  platinum-rhodium, 
  and 
  their 
  

   readings 
  were 
  carefull} 
  7 
  taken 
  at 
  the 
  following 
  melting 
  points 
  :* 
  

   tin 
  231-9°, 
  cadmium 
  320*9°, 
  zinc 
  419*4,° 
  sodium 
  sulphate 
  885°, 
  

   silver 
  960'2°, 
  copper 
  108*2*8°. 
  In 
  some 
  instances 
  the 
  reading 
  

   was 
  also 
  taken 
  at 
  the 
  melting 
  point 
  of 
  antimony 
  630*0°. 
  

  

  M 
  ' 
  anipulation. 
  — 
  When 
  the 
  furnaces 
  are 
  ready 
  for 
  an 
  experi- 
  

   ment 
  they 
  are 
  drawn 
  apart 
  on 
  their 
  carriages, 
  the 
  split 
  plugs 
  

   are 
  removed 
  and 
  the 
  thermocouples 
  pushed 
  through 
  their 
  por- 
  

   celain 
  jackets 
  till 
  the 
  junction 
  of 
  each 
  projects 
  a 
  few 
  inches 
  

   beyond 
  the 
  inner 
  ends 
  of 
  the 
  furnaces. 
  The 
  thermocouple 
  in 
  

   furnace 
  1 
  is 
  then 
  slipped 
  over 
  the 
  hook 
  Ej 
  of 
  the 
  glass 
  tube 
  

   and 
  so 
  adjusted 
  that 
  the 
  therm 
  o 
  junction 
  is 
  brought 
  close 
  

   alongside 
  of 
  the 
  sulphide 
  powder. 
  The 
  glass 
  tube 
  is 
  now 
  sup- 
  

   ported 
  and 
  guided 
  by 
  one 
  operator 
  while 
  the 
  other 
  draws 
  it 
  

   carefully 
  into 
  the 
  furnace 
  by 
  means 
  of 
  the 
  thermocouple, 
  until 
  

   the 
  glass 
  chamber 
  enclosing 
  the 
  sulphide 
  is 
  within 
  the 
  region 
  

   of 
  constant 
  temperature. 
  The 
  split 
  plug 
  B 
  (fig. 
  2) 
  is 
  now 
  

   placed 
  in 
  position. 
  Furnace 
  2 
  is 
  pushed 
  up 
  close 
  to 
  the 
  bulb 
  

   A 
  (fig. 
  1) 
  so 
  that 
  the 
  second 
  thermocouple 
  may 
  be 
  attached 
  to 
  

   the 
  hook 
  E 
  2 
  ; 
  the 
  plug 
  A 
  is 
  set 
  in 
  place, 
  and 
  while 
  the 
  two 
  

   thermocouples 
  are 
  held 
  taut 
  the 
  two 
  furnaces 
  are 
  brought 
  care- 
  

   fully 
  together 
  so 
  that 
  the 
  tube 
  is 
  not 
  displaced. 
  Although 
  the 
  

   whole 
  operation 
  requires 
  but 
  a 
  few 
  minutes, 
  the 
  temperature 
  

   in 
  the 
  middle 
  of 
  each 
  furnace 
  naturally 
  falls 
  10° 
  or 
  15°, 
  but 
  it 
  

   rises 
  rapidly 
  again 
  and 
  soon 
  returns 
  to 
  its 
  former 
  value. 
  After 
  

   a 
  period 
  of 
  several 
  hours, 
  during 
  which 
  the 
  temperature 
  is 
  

   carefully 
  maintained 
  constant, 
  the 
  furnaces 
  are 
  quickly 
  drawn 
  

   apart, 
  the 
  plugs 
  removed 
  by 
  forceps, 
  the 
  thermocouples 
  detached 
  

   and 
  the 
  tube 
  withdrawn. 
  This 
  operation 
  generally 
  requires 
  

   less 
  than 
  a 
  minute, 
  and, 
  since 
  the 
  tube 
  is 
  very 
  light 
  and 
  its 
  

   heat 
  capacity 
  small, 
  its 
  cooling 
  is 
  very 
  rapid. 
  

  

  Yapor 
  pressures 
  of 
  sulphur. 
  — 
  We 
  used 
  in 
  our 
  experiments 
  

   values 
  for 
  the 
  vapor 
  pressure 
  of 
  sulphur 
  obtained 
  by 
  other 
  

   investigators, 
  namely, 
  Ruff 
  and 
  Graf, 
  Matthies, 
  and 
  Bodenstein. 
  

   The 
  determinations 
  of 
  Ruff 
  and 
  Graff 
  which 
  extend 
  from 
  0° 
  

   to,211*3° 
  were 
  made 
  by 
  the 
  dynamic 
  method; 
  the 
  sulphur 
  was 
  

   volatilized 
  in 
  a 
  stream 
  of 
  hydrogen. 
  Bodenstein;): 
  made 
  five 
  

   determinations 
  by 
  observing 
  directly 
  the 
  boiling 
  point 
  of 
  sul- 
  

  

  * 
  The 
  nitrogen 
  thermometer 
  from 
  zinc 
  to 
  palladium, 
  Arthur 
  L. 
  Day 
  and 
  

   Robert 
  B. 
  Sosman, 
  this 
  Journal 
  (4), 
  xxix, 
  93, 
  1910. 
  

   + 
  Z. 
  anorg. 
  Chem., 
  lviii, 
  209, 
  1908. 
  

   JZ. 
  phys. 
  Chem., 
  xxx, 
  118, 
  1899. 
  

  

  