﻿186 
  

  

  Allen 
  and 
  Lombard 
  — 
  Determination 
  of 
  

  

  These 
  results 
  are 
  plotted 
  in 
  fig. 
  5. 
  They 
  are 
  expressed 
  tol- 
  

  

  erably 
  well 
  by 
  the 
  well-known 
  equation 
  : 
  log 
  p 
  = 
  — 
  ™- 
  + 
  B 
  log 
  

  

  T 
  + 
  C. 
  By 
  substituting 
  the 
  observed 
  values 
  of 
  p 
  at 
  410°, 
  460° 
  

   and 
  485° 
  respectively, 
  the 
  following 
  values 
  of 
  the 
  constants 
  

   were 
  found: 
  A 
  = 
  -96397-514, 
  B 
  = 
  +356*43227, 
  C 
  = 
  -1150- 
  

   98605. 
  From 
  these 
  values, 
  p 
  at 
  the 
  other 
  temperatures 
  was 
  

   calculated. 
  The 
  calculated 
  and 
  observed 
  values 
  of 
  p 
  are 
  com- 
  

   pared 
  in 
  the 
  following 
  table 
  : 
  

  

  Table 
  III. 
  

  

  Comparison 
  of 
  observed 
  and 
  calculated 
  values 
  of 
  p, 
  the 
  dissociation 
  pressure 
  

  

  of 
  covellite 
  

  

  Abs. 
  temp. 
  Temp. 
  C° 
  

  

  p 
  observed 
  

  

  p 
  cal. 
  

  

  diff. 
  

  

  763 
  

  

  490 
  

  

  510- 
  

  

  600' 
  

  

  — 
  90- 
  

  

  758 
  

  

  485' 
  

  

  393' 
  

  

  393* 
  

  

  o- 
  

  

  755 
  

  

  482 
  

  

  320- 
  

  

  306' 
  

  

  + 
  14- 
  

  

  748 
  

  

  475 
  

  

  170- 
  

  

  173- 
  

  

  — 
  3- 
  

  

  741 
  

  

  468 
  

  

  93- 
  

  

  100' 
  

  

  - 
  7- 
  

  

  733 
  

  

  460 
  

  

  55* 
  

  

  55- 
  

  

  o- 
  

  

  723 
  

  

  450 
  

  

  31- 
  

  

  27- 
  

  

  + 
  4- 
  

  

  707 
  

  

  433 
  

  

  ■7 
  9-7 
  

  

  11-2 
  

  

  + 
  1' 
  

  

  683 
  

  

  410 
  

  

  2-7 
  

  

  2-7 
  

  

  o- 
  

  

  673 
  

  

  400 
  

  

  1-5 
  

  

  1*8 
  

  

  — 
  o- 
  

  

  Though 
  the 
  formula 
  serves 
  fairly 
  well 
  for 
  the 
  purposes 
  of 
  

   interpolation 
  it 
  is 
  our 
  belief 
  that 
  a 
  graphic 
  interpolation 
  gives 
  

   more 
  accurate 
  results. 
  

  

  ^Results 
  of 
  other 
  observers. 
  In 
  Table 
  IY 
  our 
  results 
  are 
  com- 
  

   pared 
  with 
  those 
  of 
  other 
  observers. 
  Wasjuchnowa's 
  original 
  

   results 
  were 
  not 
  stated 
  in 
  terms 
  of 
  pressure 
  ; 
  only 
  the 
  mass 
  of 
  

   sulphur, 
  volatilized 
  at 
  a 
  measured 
  temperature 
  in 
  1 
  liter 
  of 
  

   nitrogen 
  under 
  standard 
  conditions, 
  is 
  given. 
  As 
  the 
  results 
  

   are 
  probably 
  not 
  accessible 
  to 
  every 
  reader 
  we 
  quote 
  them 
  

   below 
  in 
  their 
  original 
  form. 
  / 
  

  

  The 
  partial 
  pressure 
  of 
  the 
  sulphur 
  vapor 
  is 
  given 
  by 
  the 
  

   formula 
  

  

  m 
  

   i^32 
  

  

  in 
  

  

  + 
  

  

  1 
  

  

  = 
  p, 
  

  

  v32 
  22-4 
  

  

  where 
  m 
  is 
  the 
  mass 
  of 
  sulphur 
  volatilized 
  in 
  1 
  liter 
  of 
  nitrogen 
  

   at 
  the 
  given 
  temperature 
  and 
  the 
  pressure 
  p, 
  and 
  v 
  is 
  the 
  aver- 
  

   age 
  number 
  of 
  atoms 
  in 
  the 
  molecule 
  of 
  sulphur 
  under 
  the 
  

  

  