﻿Oxides 
  and 
  Sitljphides 
  of 
  Iron, 
  etc. 
  69 
  

  

  hours 
  was 
  about 
  520° 
  and 
  carbon 
  dioxide 
  bad 
  ceased 
  to 
  come 
  

   off. 
  Then 
  the 
  temperature 
  was 
  raised 
  to 
  about 
  900°. 
  At 
  this 
  

   temperature 
  a 
  very 
  little 
  carbon 
  dioxide 
  was 
  given 
  off. 
  After 
  

   an 
  hour 
  the 
  bulb 
  was 
  sealed. 
  The 
  product 
  was 
  gray 
  and 
  dis- 
  

   solved 
  in 
  hydrochloric 
  acid 
  with 
  evolution 
  of 
  hydrogen. 
  It 
  

   was 
  free 
  from 
  carbon. 
  A 
  determination 
  of 
  iron 
  as 
  ferric 
  

   oxide 
  gave 
  an 
  atomic 
  ratio, 
  Fe 
  1*253 
  to 
  O 
  1. 
  The 
  oxygen, 
  

   determined 
  by 
  loss 
  on 
  heating 
  the 
  substance 
  in 
  hydrogen, 
  gave 
  

   a 
  ratio 
  of 
  Fe 
  1*240 
  to 
  O 
  1. 
  The 
  mean 
  is 
  1/25 
  of 
  iron 
  to 
  1 
  of 
  

   oxygen 
  and 
  hence 
  Fe 
  5 
  4 
  represents 
  the 
  composition 
  of 
  the 
  sub- 
  

   stance. 
  The 
  atomic 
  ratio 
  very 
  likely 
  is 
  adventitious 
  and 
  the 
  

   substance 
  should 
  be 
  regarded 
  as 
  a 
  mixture 
  of 
  4 
  molecules 
  of 
  

   ferrous 
  oxide 
  and 
  1 
  atom 
  of 
  iron. 
  Such 
  a 
  mixture 
  contains 
  

   16*27 
  per 
  cent 
  of 
  metallic 
  iron. 
  

  

  A 
  number 
  of 
  investigators 
  have 
  described 
  different 
  ways 
  of 
  

   making 
  ferrous 
  oxide, 
  but 
  apparently 
  no 
  one 
  has 
  analyzed 
  the 
  

   product 
  except 
  Ruff 
  and 
  G-ersten.* 
  They 
  tried 
  to 
  make 
  it 
  by 
  

   passing 
  a 
  mixture 
  of 
  equal 
  volumes 
  of 
  hydrogen 
  and 
  carbon 
  

   dioxide 
  over 
  a 
  mixture 
  of 
  equal 
  parts 
  of 
  iron 
  carbonate 
  and 
  

   ferrous 
  oxalate 
  at 
  a 
  red 
  heat. 
  They 
  found 
  that 
  the 
  product 
  

   contained 
  FeO, 
  Fe 
  3 
  4 
  , 
  C0 
  2 
  (as 
  FeC0 
  3 
  ) 
  and 
  amorphous 
  carbon. 
  

  

  Note 
  on 
  the 
  Volatilization 
  of 
  Cadmium 
  Oxide. 
  

  

  The 
  writer 
  has 
  observed 
  that 
  cadmium 
  oxide 
  loses 
  weight 
  at 
  

   about 
  900° 
  when 
  heated 
  in 
  an 
  electric 
  furnace 
  with 
  platinum 
  

   resistance. 
  One 
  experiment 
  was 
  made 
  with 
  the 
  preparation 
  

   described 
  on 
  p. 
  66. 
  The 
  weighed 
  portion 
  was 
  in 
  an 
  nnglazed 
  

   porcelain 
  crucible. 
  The 
  temperature 
  at 
  times 
  was 
  as 
  high 
  as 
  

   the 
  melting 
  point 
  of 
  silver, 
  962°, 
  but 
  usually 
  lower. 
  The 
  

   weight 
  of 
  the 
  cadmium 
  oxide 
  after 
  heating 
  to 
  redness 
  and 
  

   cooling 
  in 
  a 
  desiccator 
  was 
  3*050 
  grams. 
  The 
  weights 
  observed 
  

   after 
  successive 
  heatings 
  were 
  : 
  3*036, 
  a 
  few 
  minutes 
  ; 
  3*029, 
  

   time 
  not 
  noted; 
  3*025, 
  1 
  hr. 
  ; 
  3*016, 
  2 
  hrs. 
  ; 
  3*007, 
  3 
  hrs. 
  ; 
  

   3*001, 
  6 
  hrs. 
  ; 
  3*000, 
  4 
  hrs. 
  The 
  total 
  loss 
  was 
  1*66 
  per 
  cent. 
  

   The 
  reddish 
  brown 
  oxide 
  had 
  changed 
  to 
  a 
  black 
  sintered 
  mass 
  

   showing 
  some 
  crystallise 
  structure. 
  About 
  the 
  top 
  of 
  the 
  

   crucible 
  was 
  a 
  reddish 
  deposit. 
  

  

  In 
  another 
  experiment 
  28*088 
  grams 
  of 
  commercial 
  cadmium 
  

   oxide 
  were 
  heated 
  successive 
  times, 
  in 
  all 
  96 
  hours. 
  The 
  total 
  

   loss 
  was 
  0*641 
  gram, 
  or 
  2*28 
  per 
  cent. 
  The 
  temperature 
  in 
  this 
  

   test 
  was 
  much 
  of 
  the 
  time 
  somewhat 
  higher 
  than 
  it 
  was 
  in 
  the 
  first. 
  

  

  The 
  results 
  show 
  that 
  reddish 
  brown 
  amorphous 
  cadmium 
  

   oxide 
  volatilizes 
  or 
  dissociates 
  slowly 
  at 
  900° 
  to 
  1000° 
  and 
  that 
  

   the 
  rate 
  of 
  loss 
  is 
  less 
  as 
  the 
  oxide 
  becomes 
  denser 
  and 
  crystal- 
  

   line. 
  

  

  Apparatus 
  has 
  not 
  been 
  available 
  for 
  the 
  determination 
  of 
  

   the 
  melting 
  point 
  or 
  for 
  the 
  investigation 
  of 
  the 
  vapor 
  or 
  dis- 
  

   sociation 
  pressure 
  of 
  cadmium 
  oxide. 
  

  

  * 
  Loc. 
  cit. 
  

  

  