﻿with 
  Sodmm 
  Peroxide. 
  33 
  

  

  against 
  B 
  while 
  the 
  water 
  in 
  it 
  is 
  stirred. 
  When 
  the 
  jacket 
  

   water 
  is 
  rapidly 
  raised 
  4° 
  or 
  5° 
  it 
  will 
  be 
  some 
  time 
  before 
  the 
  

   empty 
  can 
  E 
  is 
  warmed 
  approximately 
  as 
  much. 
  To 
  save 
  

   time 
  E 
  may 
  be 
  heated 
  by 
  putting 
  into 
  it 
  a 
  closed 
  flask 
  of 
  hot 
  

   water. 
  If 
  the 
  can 
  E 
  is 
  colder 
  than 
  the 
  water 
  in 
  B 
  when 
  the 
  

   calorimeter 
  water 
  is 
  cooler 
  than 
  the 
  jacket 
  water, 
  the 
  tempera- 
  

   ture 
  of 
  the 
  calorimeter 
  may 
  not 
  rise 
  at 
  first 
  and 
  will 
  not 
  rise 
  

   regularly 
  for 
  some 
  time. 
  And 
  it 
  is 
  better 
  not 
  to 
  let 
  the 
  water 
  

   in 
  the 
  calorimeter 
  remain 
  long 
  before 
  a 
  combustion 
  on 
  account 
  

   of 
  loss 
  by 
  evaporation. 
  

  

  Manipulation 
  — 
  The 
  sodium 
  peroxide 
  (weighed 
  in 
  a 
  glass- 
  

   stopped 
  weighing 
  bottle) 
  and 
  the 
  substance 
  to 
  be 
  burned 
  are 
  

   placed 
  in 
  the 
  open 
  bomb, 
  which 
  is 
  at 
  once 
  covered 
  with 
  a 
  plate 
  

   glass 
  cover 
  to 
  keep 
  out 
  moisture 
  from 
  the 
  air. 
  Then 
  the 
  cover 
  

   is 
  clamped 
  to 
  the 
  bomb 
  by 
  two 
  screws 
  and 
  a 
  wooden 
  piece 
  with 
  

   a 
  bit 
  of 
  rubber 
  under 
  the 
  middle 
  of 
  it. 
  The 
  ingredients 
  are 
  

   thoroughly 
  mixed 
  by 
  shaking 
  and 
  then 
  the 
  cover 
  is 
  replaced 
  

   by 
  the 
  top 
  of 
  the 
  bomb. 
  Before 
  tightening 
  the 
  screws 
  the 
  air 
  

   is 
  displaced 
  by 
  passing 
  about 
  200 
  cc 
  of 
  dry 
  oxygen* 
  through 
  

   the 
  tube 
  &, 
  fig. 
  1. 
  Next 
  the 
  screws 
  are 
  carefully 
  tightened 
  so 
  

   as 
  not 
  to 
  strain 
  them 
  and 
  the 
  valve 
  is 
  closed. 
  If, 
  however, 
  

   oxygen 
  from 
  the 
  fusion 
  is 
  to 
  be 
  collected 
  it 
  is 
  left 
  slightly 
  open 
  

   so 
  that 
  gas 
  may 
  pass 
  slowly. 
  Then 
  the 
  bomb 
  is 
  adjusted 
  as 
  

   shown 
  in 
  fig. 
  3, 
  and 
  the 
  required 
  amount 
  of 
  water 
  is 
  poured 
  

   into 
  the 
  water 
  can. 
  The 
  stirrer 
  is 
  started 
  and 
  the 
  temper- 
  

   ature 
  is 
  noted 
  each 
  minute. 
  When 
  it 
  is 
  rising 
  regularly 
  

   the 
  mixture 
  is 
  ignited 
  by 
  a 
  current 
  passing 
  four 
  32 
  candle- 
  

   power 
  lamps. 
  The 
  temperature 
  usually 
  falls 
  regularly 
  after 
  

   thirteen 
  minutes 
  and 
  is 
  observed 
  six 
  minutes 
  longer 
  in 
  order 
  to 
  

   get 
  the 
  rate 
  of 
  fall. 
  Finally 
  the 
  bulb 
  containing 
  the 
  oxygen 
  

   set 
  free 
  by 
  the 
  fusion 
  is 
  disconnected 
  and 
  the 
  bomb 
  opened 
  and 
  

   placed 
  in 
  a 
  beaker 
  of 
  water. 
  Rapid 
  evolution 
  of 
  oxygen 
  shows 
  

   that 
  the 
  mixture 
  contained 
  an 
  excess 
  of 
  peroxide. 
  After 
  the 
  

   fusion 
  has 
  disintegrated 
  the 
  bomb 
  is 
  removed 
  from 
  the 
  beaker. 
  

   If 
  an 
  hydroxide 
  insoluble 
  in 
  water 
  is 
  formed 
  it 
  is 
  dissolved 
  by 
  

   nitric, 
  acetic, 
  or 
  hydrochloric 
  acid 
  as 
  may 
  be 
  best. 
  If 
  some 
  

   unburned 
  substance 
  remains 
  it 
  is 
  collected 
  on 
  a 
  Gooch 
  filter, 
  

   washed 
  with 
  water 
  and 
  then 
  ammonia 
  to 
  remove 
  any 
  silver 
  

   chloride 
  present 
  and 
  its 
  weight 
  is 
  found. 
  If 
  any 
  gas 
  is 
  col- 
  

   lected 
  it 
  is 
  brought 
  to 
  atmospheric 
  pressure 
  and 
  known 
  temper- 
  

   ature, 
  then 
  the 
  stop-cock 
  of 
  the 
  bulb 
  Gr, 
  fig. 
  3, 
  is 
  closed 
  and 
  the 
  

   rubber 
  tubing 
  removed. 
  The 
  weight 
  of 
  the 
  bulb 
  full 
  of 
  water, 
  

   less 
  the 
  weight 
  when 
  partly 
  filled 
  with 
  the 
  oxygen 
  collected, 
  

   equals 
  the 
  number 
  of 
  cubic 
  centimeters 
  of 
  the 
  gas. 
  The 
  

   weight 
  of 
  the 
  oxygen 
  is 
  found 
  in 
  the 
  usual 
  way. 
  

  

  The 
  silver 
  cup 
  a, 
  fig. 
  1, 
  is 
  usually 
  easily 
  removed 
  from 
  the 
  

   bomb 
  after 
  an 
  experiment. 
  Sometimes 
  it 
  is 
  necessary 
  to 
  heat 
  

  

  * 
  Iron 
  wire 
  burned 
  in 
  air 
  does 
  not 
  always 
  ignite 
  the 
  peroxide 
  mixture. 
  

   Am. 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  XLIII, 
  No. 
  253.— 
  January, 
  1917. 
  

  

  