﻿W. 
  G. 
  Mixter 
  — 
  Calorimetry 
  by 
  Combustions. 
  27 
  

  

  Art. 
  II. 
  — 
  Calorimetry 
  by 
  Combustions 
  with 
  Sodium 
  Peroxide; 
  

  

  by 
  W. 
  G. 
  Mixter. 
  

  

  [Contributions 
  from 
  the 
  Sheffield. 
  Chemical 
  Laboratory 
  of 
  Yale 
  University.] 
  

  

  Fusion 
  with 
  sodium 
  peroxide 
  is 
  the 
  only 
  way 
  known 
  for 
  

   finding 
  the 
  heat 
  of 
  oxidation 
  of 
  elements 
  which 
  do 
  not 
  burn 
  

   in 
  oxygen 
  and 
  which 
  form 
  oxides 
  insoluble 
  in 
  acids. 
  The 
  

   method 
  is 
  adapted 
  to 
  the 
  determination 
  of 
  the 
  heat 
  of 
  forma- 
  

   tion 
  of 
  the 
  oxides 
  of 
  a 
  metal 
  and 
  also 
  the 
  heat 
  of 
  combination 
  of 
  

   metallic 
  oxides 
  with 
  sodium 
  oxide. 
  The 
  writer 
  has 
  used 
  the 
  

   method 
  the 
  past 
  ten 
  years 
  and 
  can 
  now 
  describe 
  it 
  more 
  com- 
  

   pletely 
  than 
  was 
  done 
  in 
  any 
  of 
  his 
  papers. 
  

  

  The 
  method 
  is 
  indirect 
  and 
  the 
  heat 
  effect 
  sought 
  is 
  not 
  the 
  

   observed 
  effect 
  ; 
  hence 
  burning 
  in 
  condensed 
  oxygen 
  is 
  prefer- 
  

   able 
  where 
  possible. 
  For 
  example, 
  when 
  carbon 
  is 
  burned 
  

   with 
  sodium 
  peroxide 
  the 
  observed 
  heat 
  (x) 
  is 
  the 
  result 
  of 
  the 
  

   following 
  reaction 
  

  

  2Na 
  2 
  2 
  + 
  C 
  = 
  Na 
  2 
  C0 
  3 
  + 
  Nzfi 
  = 
  x 
  

  

  and 
  x 
  equals 
  the 
  heat 
  of 
  formation 
  of 
  carbon 
  dioxide 
  plus 
  the 
  

   heat 
  of 
  combination 
  of 
  carbon 
  dioxide 
  with 
  sodium 
  oxide 
  and 
  

   less 
  the 
  heat 
  required 
  to 
  separate 
  two 
  atoms 
  of 
  oxygen 
  from 
  

   two 
  molecules 
  of 
  sodium 
  peroxide, 
  thus 
  

  

  x 
  = 
  C 
  + 
  20 
  + 
  (Na 
  2 
  + 
  C0 
  2 
  ) 
  - 
  (2Na 
  2 
  + 
  20) 
  

   and 
  

  

  C 
  4- 
  20 
  = 
  x 
  - 
  (Na 
  2 
  + 
  C0 
  2 
  ) 
  + 
  (2Na 
  2 
  + 
  20) 
  

  

  Moreover, 
  many 
  substances 
  do 
  not 
  give 
  with 
  sodium 
  peroxide 
  

   sufficient 
  heat 
  to 
  fuse 
  the 
  mixture 
  and 
  hence 
  some 
  readily 
  com- 
  

   bustible 
  substance, 
  such 
  as 
  sulphur 
  or 
  carbon, 
  must 
  be 
  added, 
  

   which 
  gives 
  in 
  many 
  cases 
  the 
  larger 
  part 
  of 
  the 
  total 
  heat 
  

   effect. 
  

  

  As 
  yet 
  we 
  have 
  only 
  a 
  few 
  results 
  obtained 
  by 
  fusion 
  with 
  

   sodium 
  peroxide 
  to 
  compare 
  with 
  those 
  by 
  other 
  methods. 
  

   They 
  are 
  

  

  Sodium 
  peroxide 
  

  

  method 
  Other 
  methods 
  

  

  C 
  + 
  20 
  = 
  CO, 
  + 
  96-4* 
  94-7* 
  

  

  Ti 
  + 
  20 
  = 
  TiO,(amor.) 
  215'6f 
  Ti0 
  2 
  (crys.) 
  218-4f 
  

  

  3Fe 
  + 
  40 
  267.5J 
  265-2J 
  

  

  2Na 
  + 
  S 
  + 
  40 
  326'7§ 
  'S28'6\\ 
  

  

  3Na 
  + 
  P 
  -f- 
  40 
  451-4 
  452-4 
  

  

  *This 
  Journal, 
  xxix, 
  130 
  ; 
  ibid., 
  xix, 
  434. 
  

  

  f 
  Ibid., 
  xxvii, 
  343. 
  J 
  Ibid. 
  , 
  xxi 
  

  

  §Ibid., 
  xxvi, 
  125. 
  | 
  Thomsen. 
  

  

  