ADecemUbrerPmT' }  Preservation  of  Hydrogen  Peroxide.  541 
Series  III. — Effect  of  Acids  in  Different  Strengths. 
One  c.c.  of  the  solutions  when  prepared,  required  16.35  cc-  tenth- 
normal thiosulphate.  In  adding  the  acids  the  same  volume  was 
introduced  in  each  case  so  that  the  resulting  solutions  were  all  of 
the  same  strength. 
Age  at  time  of  test 
Strength  of  acid  6  weeks  7  months 
HC1—  14.80...,   9.45 
25 
HG1  —  14-65   8.30 
50 
HC1  —   J4-85   8.70 
100 
HC1  —  :  •  .11.80   I.40 
200 
H2SO4— • .....I5.20   9.75 
25 
H2S04-^-  I4-40   7-75 
5° 
H2S04  —   J3-75   5-25 
100 
H2S04  —  x3-6o   4  05 
200 
H3PO4  —  15-45  10.65 
25 
H3PO4  —  I5-40  11.60 
5o 
H3PO4  —  1540.,.  n.05 
100 
H3PO4—  r510   9-55 
200 
Boracic  acid   8 . 41 
Series  IV :  Solutions  t^ 
Salts  alone  and  with  Acetanilide. 
The  entire  sample  of  H202  used  in  this  series  was  made  TVo 
normal  in  HC1.  The  strength  of  acetanilide  was  I  to  2000.  The 
salts  were  added  in  strong  solution,  the  same  volume  being  used  in 
each  case.  Where  no  salts  were  added  an  equal  volume  of  pure 
water  was  used,  so  that  all  solutions  have  the  same  initial  strength 
in  H202.  The  concentrations  of  the  salts  indicated  are  in  terms  of 
the  anhydrous  compounds.  To  the  solutions  containing  Na2Si03 
there  was  added  enough  concentrated  HQ  to  neutralize  the  former, 
