﻿190 
  

  

  Allen 
  and 
  Lombard 
  — 
  Determination 
  of 
  

  

  Table 
  VI. 
  

   Comparison 
  of 
  magnetic 
  behavior 
  with 
  composition. 
  

  

  

  

  Pres- 
  

  

  

  Tem- 
  

  

  sure 
  of 
  

  

  Tem- 
  

   pera- 
  

   ture 
  of 
  

  

  pera- 
  

   ture 
  of 
  

   sul- 
  

  

  sul- 
  

   phur 
  

   in 
  mm. 
  

  

  pyrite 
  

   in 
  0°. 
  

  

  phur 
  

   in 
  C°. 
  

  

  of 
  

   mer- 
  

   c 
  ary 
  

  

  610 
  

  

  250 
  

  

  12 
  

  

  610 
  

  

  236 
  

  

  6 
  

  

  665 
  

  

  380 
  

  

  259 
  

  

  665 
  

  

  378 
  

  

  243 
  

  

  680 
  

  

  418 
  

  

  505 
  

  

  680 
  

  

  418 
  

  

  505 
  

  

  680 
  

  

  411 
  

  

  453 
  

  

  680 
  

  

  424 
  

  

  554 
  

  

  680 
  

  

  421 
  

  

  530 
  

  

  595 
  

  

  209 
  

  

  3 
  

  

  595 
  

  

  228 
  

  

  4 
  

  

  Magnetic 
  

   behavior 
  

  

  magnetic 
  

  

  non- 
  

   magnetic 
  

  

  magnetic 
  

  

  non- 
  

   magnetic 
  

  

  magnetic 
  

  

  non- 
  

   magnetic 
  

  

  Portion 
  

   analyzed 
  

  

  magnetic 
  

   portion 
  

  

  the 
  whole 
  

  

  magnetic 
  

   portion 
  

  

  the 
  whole 
  

  

  magnetic 
  

   portion 
  

  

  the 
  whole 
  

  

  magnetic 
  

   portion 
  

  

  the 
  whole 
  

  

  Analysis 
  

  

  Weight 
  

   of 
  sul- 
  

   phide 
  

   taken 
  

  

  Weight 
  

  

  of 
  

   Fe 
  2 
  3 
  

   found 
  

  

  0*1043 
  

  

  0-0735 
  

  

  •1040 
  

  

  •0788 
  

  

  •2030 
  

  

  •1361 
  

  

  •1048 
  

  

  •0825 
  

  

  •0754 
  

  

  •0514 
  

  

  ■2145 
  

  

  .1446 
  

  

  •1353 
  

  

  •1068 
  

  

  •2244 
  

  

  •1499 
  

  

  •2047 
  

  

  •1375 
  

  

  •0792 
  

  

  •0557 
  

  

  •1011 
  

  

  •0685 
  

  

  Per- 
  

   cent- 
  

   age 
  of 
  

  

  iron 
  

  

  49-29 
  

   53-00 
  

   46-90 
  

   55-07 
  

   48-43 
  

   47'16 
  

   55-22 
  

   46*73 
  

   46-99 
  

   61'94 
  

   47-39 
  

  

  crepancy 
  in 
  the 
  table, 
  but 
  even 
  here 
  the 
  result 
  involves 
  an 
  

   error 
  of 
  less 
  than 
  a 
  milligram. 
  For 
  a 
  rigorous 
  comparison 
  of 
  

   the 
  methods, 
  more 
  material 
  should 
  of 
  course 
  have 
  been 
  taken 
  

   for 
  analysis, 
  but 
  small 
  quantities 
  of 
  pyrite 
  were 
  used 
  in 
  the 
  

   pressure 
  experiments 
  because 
  in 
  that 
  way 
  a 
  uniform 
  tempera- 
  

   ture 
  for 
  the 
  whole 
  charge 
  was 
  more 
  certainly 
  attained. 
  

  

  Dissociation 
  pressures. 
  — 
  The 
  dissociation 
  pressures 
  estab- 
  

   lished 
  by 
  the 
  aid 
  of 
  the 
  magnetic 
  method 
  are 
  tabulated 
  in 
  

   Table 
  VII 
  and 
  plotted 
  in 
  fig. 
  6. 
  

  

  These 
  results 
  are 
  expressed 
  by 
  the 
  equation 
  : 
  log 
  p 
  = 
  — 
  m 
  + 
  

  

  BlogT 
  + 
  C, 
  with 
  about 
  the 
  same 
  degree 
  of 
  accuracy, 
  as 
  are 
  

   those 
  with 
  covellite. 
  The 
  values 
  of 
  log 
  p 
  at 
  595°, 
  645° 
  and 
  

   672° 
  were 
  chosen 
  for 
  the 
  computation 
  of 
  the 
  constants. 
  The 
  

   values 
  found 
  were: 
  A 
  = 
  + 
  191942-61, 
  B 
  = 
  - 
  434-195075, 
  

  

  