﻿188 
  Allen 
  and 
  Lombard 
  — 
  Determination 
  of 
  

  

  same 
  conditions. 
  Wasjuchnowa 
  bad 
  at 
  her 
  disposal 
  only 
  one 
  

   value 
  of 
  v 
  (at 
  the 
  boiling 
  point 
  of 
  sulphur) 
  and 
  was, 
  therefore, 
  

   able 
  to 
  calculate 
  only 
  one 
  of 
  her 
  results 
  in 
  terms 
  of 
  pressure. 
  

   Preunner 
  and 
  Brockmoller* 
  by 
  the 
  aid 
  of 
  their 
  data 
  on 
  the 
  

   vapor 
  density 
  of 
  sulphur 
  calculated 
  a 
  part 
  of 
  her 
  results 
  (417°- 
  

   502°) 
  in 
  terms 
  of 
  p 
  by 
  a 
  method 
  which 
  they 
  describe. 
  In 
  a 
  

   similar 
  way 
  we 
  completed 
  the 
  series. 
  The 
  results 
  are 
  given 
  in 
  

   Table 
  Y. 
  Wasjuchnowa 
  also 
  gives 
  one 
  other 
  result 
  by 
  a 
  differ- 
  

   ent 
  method, 
  f 
  viz. 
  

  

  Sclrwefel 
  in 
  g 
  iiberfuhrt 
  

   Teinperatur 
  des 
  Schwefels 
  Temperahir 
  des 
  CuS 
  von 
  1 
  1. 
  N 
  bei 
  0° 
  C 
  

  

  C° 
  T. 
  abs. 
  C° 
  T, 
  abs. 
  mid 
  760 
  mra 
  

  

  216-5 
  489*5 
  425*2 
  698'2 
  0-0559 
  

  

  If 
  the 
  mass 
  of 
  the 
  sulphur 
  is 
  calculated 
  as 
  above 
  in 
  terms 
  of 
  

   2?, 
  the 
  value 
  7 
  mm 
  is 
  obtained 
  which 
  we 
  give 
  in 
  the 
  table. 
  If, 
  

   however, 
  we 
  take 
  the 
  vapor 
  pressure 
  of 
  sulphur 
  from 
  Ruff 
  & 
  

   Graf's 
  results 
  we 
  get, 
  at 
  216*5° 
  by 
  a 
  short 
  extrapolation, 
  4 
  mm 
  . 
  

   The 
  discrepancy 
  is 
  unaccounted 
  for. 
  In 
  the 
  lower 
  part 
  of 
  the 
  

   curve 
  our 
  results 
  agree 
  surprisingly 
  well 
  with 
  those 
  of 
  Was- 
  

   juchnowa,^; 
  while 
  both 
  are 
  much 
  lower 
  than 
  those 
  of 
  Preunner 
  

   and 
  Brockmoller. 
  The 
  suspicion 
  naturally 
  arises 
  that 
  their 
  

   higher 
  results 
  have 
  been 
  due 
  to 
  water 
  vapor 
  in 
  their 
  apparatus 
  

   or 
  in 
  the 
  sulphide 
  or 
  possibly 
  free 
  sulphur 
  in 
  the 
  latter, 
  but 
  an 
  

   examination 
  of 
  their 
  procedure 
  seems 
  to 
  set 
  the 
  suspicion 
  at 
  

   rest.§ 
  It 
  is 
  certain 
  that 
  their 
  temperatures 
  were 
  not 
  very 
  

   uniform 
  ; 
  variations 
  of 
  5° 
  occurred 
  along 
  the 
  dissociation 
  

   chamber 
  of 
  their 
  apparatus, 
  but 
  even 
  this 
  would 
  not 
  account 
  

   for 
  the 
  great 
  differences 
  between 
  their 
  results 
  and 
  ours. 
  They 
  

   admit 
  that 
  their 
  pressure 
  measurements 
  varied 
  considerably 
  

   (Die 
  Messungen 
  wichen 
  erheblich 
  voneinander 
  ab), 
  but 
  they 
  

   do 
  not 
  account 
  for 
  the 
  variation. 
  The 
  small 
  temperature 
  in- 
  

   terval 
  within 
  which 
  the 
  dissociation 
  of 
  cupric 
  sulphide 
  reverses 
  

   itself 
  in 
  the 
  lower 
  part 
  of 
  our 
  curve, 
  and 
  the 
  care 
  with 
  which 
  

   the 
  temperature 
  measurements 
  were 
  performed 
  give 
  us 
  special 
  

   confidence 
  in 
  that 
  portion 
  of 
  it. 
  

  

  2. 
  Dissociation 
  pressure 
  of 
  pyrite. 
  

  

  The 
  mineral 
  used 
  in 
  these 
  experiments 
  was 
  a 
  very 
  pure 
  

   variety 
  of 
  pyrite 
  of 
  the 
  kind 
  used 
  in 
  wireless 
  telegraphy, 
  which 
  

   is 
  said 
  to 
  come 
  from 
  Colorado. 
  No 
  impurities 
  could 
  be 
  cer- 
  

   tainly 
  detected 
  in 
  1 
  g. 
  though 
  doubtful 
  traces 
  of 
  silica 
  and 
  

  

  *Z. 
  phys. 
  Chem., 
  lxxxi, 
  150, 
  1912. 
  

  

  f 
  Das 
  Gleichgewicht 
  Cupro-cuprisulfid, 
  Dissertation, 
  Berlin, 
  1909, 
  p. 
  25. 
  

   X 
  W. 
  used 
  for 
  the 
  two 
  points 
  obtained 
  at 
  484° 
  and 
  502° 
  a 
  different 
  method 
  

   for 
  condensing 
  the 
  sulphur. 
  

  

  §Z. 
  phys. 
  Chem., 
  lxxxi, 
  152, 
  1912. 
  

  

  