﻿Oxides 
  and 
  Sulphides 
  of 
  Iron, 
  etc. 
  63 
  

  

  For 
  the 
  heat 
  effect 
  of 
  one 
  and 
  two 
  atoms 
  of 
  sulphur 
  we 
  

   have 
  

  

  Fe 
  -J- 
  S 
  = 
  FeS 
  (amor.) 
  + 
  18,800 
  c 
  

   FeS 
  (amor.) 
  + 
  S 
  = 
  FeS 
  2 
  (crys.) 
  + 
  16,700 
  

  

  This 
  accords 
  with 
  the 
  oxides 
  of 
  iron 
  where 
  one 
  atom 
  of 
  

   oxygen 
  combining 
  with 
  iron 
  produces 
  but 
  little 
  more 
  heat 
  than 
  

   when 
  combining 
  with 
  ferrous 
  oxide. 
  

  

  Zinc 
  Sidjphide. 
  — 
  The 
  zinc 
  blende 
  was 
  a 
  honey 
  yellow, 
  trans- 
  

   lucent 
  piece 
  with 
  brilliant 
  cleavage 
  planes. 
  The 
  zinc 
  found 
  

   in 
  it 
  was 
  67*10 
  per 
  cent 
  ; 
  theory 
  67*14 
  per 
  cent. 
  Zinc 
  sulphide 
  

   was 
  prepared 
  as 
  follows 
  : 
  zinc 
  oxide 
  was 
  heated 
  gradually 
  to 
  a 
  

   bright 
  red 
  heat 
  in 
  a 
  current 
  of 
  dry 
  hydrogen 
  sulphide 
  and 
  

   allowed 
  to 
  cool 
  in 
  the 
  gas. 
  After 
  pulverizing 
  it 
  was 
  heated 
  

   again 
  in 
  the 
  gas 
  to 
  about 
  500°. 
  A 
  determination 
  of 
  zinc 
  in 
  

   this 
  sulphide 
  gave 
  67*19 
  per 
  cent. 
  Under 
  the 
  microscope 
  a 
  

   few 
  bright 
  surfaces 
  were 
  visible 
  in 
  the 
  apparently 
  amorphous 
  

   powder. 
  One 
  would 
  expect 
  it 
  to 
  be 
  crystalline 
  since 
  its 
  heat 
  

   of 
  formation 
  is 
  the 
  same 
  as 
  that 
  of 
  blende, 
  and 
  also 
  because 
  

   Deville 
  and 
  Troost* 
  obtained 
  crystalline 
  zinc 
  sulphide 
  by 
  heat- 
  

   ing 
  the 
  amorphous 
  in 
  hydrogen 
  sulphide, 
  probably 
  hotter 
  or 
  

   longer 
  than 
  the 
  writer 
  did. 
  

  

  The 
  fusions 
  were 
  treated 
  with 
  water 
  and 
  the 
  zinc 
  hydroxide 
  

   formed 
  was 
  dissolved 
  by 
  acetic 
  acid. 
  The 
  zinc 
  sulphide 
  left 
  

   was 
  collected 
  and 
  weighed. 
  

  

  The 
  results 
  are 
  given 
  on 
  the 
  following 
  page. 
  

  

  The 
  average 
  of 
  the 
  results 
  for 
  the 
  blende 
  is 
  2005°. 
  For 
  the 
  

   gram 
  molecule 
  it 
  is 
  195,300°. 
  The 
  heat 
  effect 
  of 
  Zn 
  + 
  S 
  is 
  

   derived 
  thus 
  : 
  

  

  Zn 
  -1- 
  Na 
  2 
  2 
  = 
  67,600 
  c 
  f 
  

  

  S 
  + 
  3Na 
  2 
  2 
  _ 
  _ 
  _ 
  = 
  169,000 
  

  

  Zn 
  + 
  S+ 
  4Na 
  2 
  2 
  = 
  236,600 
  

  

  ZnS 
  + 
  4Ka 
  2 
  2 
  = 
  195,300 
  

  

  Zn 
  + 
  S 
  (rhombic) 
  = 
  ZnS 
  (crys.) 
  = 
  41,300 
  

  

  The 
  average 
  of 
  the 
  results 
  for 
  the 
  zinc 
  sulphide 
  made 
  is 
  

   1992 
  c 
  , 
  which 
  gives 
  42,500° 
  for 
  Zn 
  + 
  S. 
  If 
  we 
  exclude 
  the 
  

   lowest 
  result, 
  1970 
  c 
  , 
  the 
  mean 
  of 
  the 
  other 
  two 
  is 
  2003 
  c 
  and 
  

   we 
  have 
  41,300°. 
  Evidently 
  the 
  artificial 
  sulphide 
  has 
  the 
  

   same 
  heat 
  of 
  formation 
  as 
  zinc 
  blende. 
  

  

  Cadmium. 
  — 
  Cadmium 
  chips 
  which 
  passed 
  through 
  a 
  J 
  mm 
  

   mesh 
  were 
  used 
  in 
  the 
  work. 
  An 
  analysis 
  of 
  the 
  sample 
  gave 
  

   Cd 
  99*96 
  per 
  cent, 
  Fe 
  0*005. 
  The 
  metal, 
  as 
  is 
  well 
  known, 
  

   oxidizes 
  slowly 
  and 
  superficially 
  in 
  ordinary 
  air. 
  In 
  a 
  desicca- 
  

   tor, 
  however, 
  it 
  remains 
  bright. 
  On 
  page 
  65 
  are 
  the 
  data 
  

   obtained 
  from 
  combustions 
  with 
  sodium 
  peroxide. 
  

  

  * 
  C. 
  R., 
  lii, 
  920, 
  1861. 
  f 
  This 
  Journal, 
  xxx, 
  199. 
  

  

  