﻿Chemistry 
  and 
  Physics. 
  69 
  

  

  be 
  detected 
  at 
  the 
  anode 
  in 
  five 
  minutes. 
  Using 
  a 
  cold 
  saturated 
  

   solution 
  of 
  potassium 
  sulphate 
  in 
  dilute 
  sulphuric 
  acid, 
  a 
  consider- 
  

   able 
  amount 
  of 
  crystallized 
  potassium 
  persulphate 
  may 
  be 
  obtained 
  

   in 
  10 
  minutes. 
  A 
  longer 
  time 
  is 
  required 
  for 
  the 
  formation 
  of 
  

   the 
  ammonium 
  salt. 
  — 
  Chem. 
  Centr. 
  1895, 
  i, 
  591, 
  ii, 
  476; 
  J. 
  Chem. 
  

   jSoc, 
  Ixx, 
  ii, 
  519, 
  September, 
  1896. 
  g. 
  e. 
  b. 
  

  

  g 
  4. 
  On 
  the 
  Reaction 
  of 
  Silver 
  oxide 
  upon 
  Hydrogen 
  Peroxide. 
  

   — 
  The 
  equation 
  expressing 
  the 
  decomposition 
  ol 
  silver 
  oxide 
  by 
  

   hydrogen 
  peroxide 
  was 
  for 
  a 
  long 
  time 
  believed 
  to 
  be 
  the 
  follow- 
  

  

  Ag,0 
  + 
  H 
  2 
  2 
  = 
  Ag 
  2 
  + 
  H 
  2 
  + 
  2 
  . 
  

  

  Berthelot, 
  however, 
  substituted 
  for 
  this 
  the 
  more 
  complex 
  equa- 
  

   tion 
  : 
  

  

  (Ag 
  5 
  0), 
  + 
  (H 
  ,O 
  s 
  ), 
  = 
  ( 
  Ag, 
  ), 
  + 
  (Ag 
  2 
  0), 
  + 
  ( 
  H.O), 
  + 
  O, 
  

  

  Riegler 
  has 
  now 
  studied 
  this 
  reaction 
  more 
  carefully 
  and 
  has 
  

   come 
  to 
  the 
  conclusion 
  that 
  neither 
  of 
  the 
  above 
  equations 
  correctly 
  

   represents 
  the 
  actual 
  changes 
  taking 
  place. 
  He 
  therefore 
  substi- 
  

   tutes 
  for 
  them 
  the 
  following 
  one: 
  

  

  (Ag.Oj. 
  + 
  tH.OJ, 
  = 
  Ag 
  4 
  + 
  (H 
  s 
  O) 
  3 
  + 
  (0 
  2 
  ) 
  a 
  . 
  

  

  Subsequently 
  the 
  silver 
  oxide 
  Ag 
  4 
  splits 
  up 
  into 
  the 
  oxide 
  Ag 
  2 
  

   and 
  free 
  silver: 
  

  

  Ag 
  4 
  = 
  Ag 
  3 
  + 
  A<r 
  a 
  . 
  

  

  — 
  Chem. 
  Centr., 
  1895, 
  ii, 
  545; 
  J. 
  Chem. 
  JSoc, 
  Ixx, 
  ii, 
  471, 
  August, 
  

   1896. 
  G. 
  F. 
  B. 
  

  

  5. 
  On 
  /Silver 
  per 
  odiy 
  nitrate. 
  — 
  The 
  black 
  deposit 
  which 
  is 
  

   formed 
  at 
  the 
  anode 
  when 
  a 
  solution 
  of 
  silver 
  nitrate 
  is 
  electro- 
  

   lyzed, 
  and 
  which 
  was 
  first 
  observed 
  by 
  Ritter 
  in 
  1814, 
  has 
  been 
  

   investigated 
  by 
  Sulc. 
  The 
  cathode 
  was 
  a 
  platinum 
  dish 
  and 
  the 
  

   anode 
  a 
  strip 
  of 
  platinum 
  foil 
  cut 
  in 
  the 
  form 
  of 
  a 
  comb 
  and 
  rolled 
  

   up. 
  The 
  solution 
  contained 
  15 
  per 
  cent 
  of 
  silver 
  nitrate 
  and 
  a 
  

   current 
  of 
  0*06 
  ampere 
  was 
  employed, 
  the 
  density 
  at 
  the 
  cathode 
  

   being 
  0*0033 
  ampere 
  per 
  centimeter. 
  After 
  three 
  or 
  four 
  hours, 
  

   the 
  solution, 
  now 
  contaminated 
  with 
  free 
  nitric 
  acid, 
  was 
  renewed. 
  

   The 
  crystalline 
  deposit 
  on 
  the 
  anode 
  was 
  removed 
  by 
  means 
  of 
  a 
  

   glass 
  rod 
  and 
  washed 
  until 
  free 
  from 
  silver. 
  On 
  analysis 
  it 
  gave 
  

   numbers 
  agreeing 
  with 
  the 
  formula 
  AgJTO 
  u 
  . 
  It 
  was 
  in 
  the 
  

   form 
  of 
  beautiful 
  black 
  octahedra 
  having 
  a 
  metallic 
  luster 
  and 
  a 
  

   specific 
  gravity 
  of 
  5*65. 
  In 
  dry 
  air 
  it 
  is 
  fairly 
  stable 
  at 
  the 
  ordi- 
  

   nary 
  temperature, 
  but 
  when 
  quickly 
  heated 
  to 
  155° 
  it 
  evolves 
  

   oxygen 
  and 
  yields 
  a 
  voluminous 
  dark 
  brown 
  powder. 
  Water 
  

   decomposes 
  it 
  only 
  slightly, 
  silver 
  nitrate 
  going 
  into 
  solution. 
  

   When 
  boiled 
  w 
  r 
  ith 
  water 
  for 
  a 
  day 
  and 
  a 
  half, 
  the 
  silver 
  is 
  depos- 
  

   ited 
  in 
  the 
  form 
  of 
  a 
  mirror. 
  When 
  boiled 
  with 
  alcohol, 
  aldehyde 
  

   is 
  formed 
  and 
  a 
  mirror 
  deposited 
  ; 
  this 
  mirror 
  being 
  tine 
  if 
  a 
  few 
  

   drops 
  of 
  ammonia 
  be 
  added. 
  Oxalic 
  acid 
  decomposes 
  it 
  com- 
  

   pletely 
  with 
  evolution 
  of 
  C0 
  2 
  ; 
  and 
  ammonia, 
  with 
  evolution 
  of 
  

   nitrogen. 
  Since 
  1*40, 
  the 
  percentage 
  of 
  nitrogen, 
  corresponds 
  

   to 
  a 
  percentage 
  of 
  silver 
  as 
  AgNO 
  s 
  of 
  12 
  61, 
  and 
  since 
  this 
  

  

  