﻿5 
  8 
  Mixter 
  — 
  Heat 
  of 
  Formation 
  of 
  the 
  

  

  !Na 
  a 
  Fe 
  a 
  4 
  , 
  is 
  formed 
  in 
  the 
  sodium 
  peroxide 
  fusions, 
  but 
  since 
  

   the 
  heat 
  of 
  the 
  reaction 
  of 
  ferric 
  oxide 
  and 
  sodium 
  oxide 
  is 
  

   much 
  greater 
  than 
  that 
  of 
  alumina 
  and 
  chromium 
  sesquioxide, 
  

   it 
  is 
  probable 
  that 
  sodium 
  orthoferrite 
  is 
  formed. 
  The 
  formula 
  

   a?Na 
  2 
  O.Fe 
  2 
  3 
  is 
  used 
  in 
  equations 
  to 
  indicate 
  that 
  the 
  composi- 
  

   tion 
  of 
  the 
  ferrite 
  is 
  not 
  known. 
  

  

  For 
  the 
  heat 
  of 
  formation 
  of 
  ferric 
  oxide 
  we 
  have 
  

  

  2Fe 
  + 
  3Na 
  2 
  2 
  = 
  xNa,fi.¥efi 
  a 
  -f 
  xNafi 
  + 
  192,000 
  c 
  

  

  3Na 
  2 
  + 
  30 
  = 
  3]STa 
  2 
  2 
  + 
  58,200 
  

  

  2Fe 
  + 
  30 
  + 
  a-Na 
  2 
  = 
  £cNa 
  2 
  O.Fe 
  2 
  3 
  + 
  250,200 
  

  

  Fe 
  2 
  3 
  + 
  £cNa 
  2 
  = 
  a?Na 
  a 
  O.Fe 
  a 
  O 
  s 
  + 
  . 
  _ 
  _ 
  58,000 
  

  

  2Fe 
  + 
  30 
  = 
  Fe 
  9 
  0, 
  + 
  _ 
  _.. 
  192,200 
  

  

  2 
  3 
  

  

  Ferrous 
  Oxide. 
  — 
  The 
  various 
  products 
  obtained 
  by 
  heating 
  

   ferrous 
  oxalate 
  for 
  the 
  purpose 
  of 
  making 
  ferrous 
  oxide 
  are 
  

   described 
  in 
  a 
  note 
  on 
  p. 
  68. 
  The 
  substance 
  used 
  in 
  the 
  fol- 
  

   lowing 
  calorimetric 
  work 
  was 
  a 
  mixture 
  of 
  ferrous 
  oxide 
  and 
  

   metallic 
  iron, 
  containing 
  16*27 
  per 
  cent 
  of 
  the 
  latter. 
  It 
  was 
  

   free 
  from 
  carbon. 
  

  

  Substance 
  (FeO 
  3*349, 
  Fe 
  0*651) 
  4*000 
  4*000 
  grams. 
  

  

  Sulphur 
  2-000 
  2*000 
  

  

  Sodium 
  peroxide 
  _ 
  26* 
  26* 
  

  

  Heat 
  effect 
  _ 
  14023° 
  14027° 
  

  

  of 
  sulphur 
  10480 
  10480 
  

  

  of 
  iron 
  for 
  ignition 
  40 
  40 
  

  

  " 
  of 
  0*651 
  grm. 
  of 
  Fe 
  1119 
  1119 
  

  

  of 
  3*349 
  grm. 
  of 
  FeO 
  2384 
  2388 
  

  

  oflgrm.\)fFeO 
  712 
  713 
  

  

  For 
  2 
  gram 
  molecules 
  of 
  ferrous 
  oxide 
  we 
  have 
  712° 
  X 
  

   143-68 
  = 
  102300°, 
  and 
  for 
  the 
  heat 
  of 
  oxidation 
  the 
  following 
  : 
  

  

  2FeO 
  + 
  Na 
  2 
  2 
  + 
  a;Na 
  2 
  = 
  _ 
  _. 
  102,300 
  c 
  

  

  Na 
  2 
  + 
  O 
  = 
  19,400 
  

  

  2FeO 
  + 
  O 
  + 
  <cNa,0 
  = 
  . 
  ._ 
  _ 
  121,700 
  

  

  Fe 
  2 
  O 
  a 
  + 
  ^Na 
  2 
  = 
  58,000 
  

  

  2FeO 
  + 
  O 
  = 
  63,700 
  

  

  and 
  for 
  the 
  heat 
  of 
  formation 
  of 
  ferrous 
  oxide 
  

  

  (2Fe 
  + 
  30) 
  - 
  (2FeO 
  + 
  O) 
  = 
  2(Fe 
  + 
  O) 
  =. 
  128500° 
  

   and 
  Fe 
  + 
  O 
  = 
  FeO 
  + 
  64300° 
  

  

  Ferrous 
  Ferric 
  Oxide. 
  — 
  Attempts 
  to 
  burn 
  iron 
  completely 
  

   were 
  not 
  successful, 
  hence 
  the 
  heat 
  effect 
  of 
  oxygen 
  taken 
  up 
  

   was 
  found. 
  The 
  iron, 
  preparation 
  " 
  B,*' 
  was 
  placed 
  in 
  the 
  

   hemispherical 
  bottom 
  of 
  a 
  steel 
  bomb, 
  which 
  was 
  then 
  repeat- 
  

   edly 
  exhausted 
  and 
  filled 
  with 
  dry 
  oxygen, 
  fairly 
  free 
  from 
  

   nitrogen, 
  and 
  finally 
  at 
  a 
  pressure 
  of 
  12 
  to 
  15 
  atmospheres. 
  

  

  