4H 
Test  for  Salicylic  Acid. 
f  Am.  Jour.  Pharm. 
I  September,  189!). 
HYDROGEN    PEROXIDE   AS  A  TEST  FOR  SALICYLIC 
ACID. 
By  W..E.  Ridenour. 
The  writer,  having  had  a  quantity  of  sodium  salicylate  which  was 
not  of  the  required  whiteness,  attempted  to  bleach  the  same  by  the  use 
of  hydrogen  peroxide,  whereupon  the  sodium  salt  developed  a  beauti- 
ful cherry  red  color.  The  thought  then  suggested  itself  that 
hydrogen  peroxide  might  be  used  as  a  test  for  salicylic  acid,  and  a 
series  of  experiments  were  performed  for  determining  its  availability 
in  this  respect. 
The  United  States  Pharmacopoeia  gives  the  following  charac- 
ters and  tests  of  identity  for  salicylic  acid :  Physical  appearance ; 
solubility  in  different  solvents ;  melting-point  ;  reaction  with  ferric 
chloride,  and  odor  in  the  presence  of  sulphuric  acid  and  methyi 
alcohol  upon  heating.  In  addition  to  these,  the  British  Pharma- 
copoeia gives  the  uranium  nitrate  test.  In  Prescott's  "Organic 
Analysis"  we  also  find  the  following:  Reactions  with  bromine  water, 
nitric  acid,  copper  sulphate,  glucose,  sodium  amalgam,  and  lime. 
Before  giving  the  results  of  his  experiments  the  author  wishes  to 
state  that  the  value  of  hydrogen  peroxide  as  a  test  for  salicylic 
acid  depends  upon  the  presence  of  an  ammoniacal  solution  of 
ammonium  carbonate,  the  U.S.P.  solution  having  been  found  best 
adapted  for  the  purpose  ;  also  that  the  solution  of  hydrogen  peroxide 
used  contained  2-301  volumes  of  available  oxygen.  The  solution 
of  sodium  salicylate  designated  in  the  first  column  of  the  following 
statements  was  a  10  per  cent,  solution. 
Sodium 
Salicylate 
Solution, 
C.c.  Taken. 
Water  Suffi- 
cient tc 
Make  100  C.c. 
Hydrogen 
Peroxide 
Solution, 
C.c.  Taken. 
Ammonium 
Carbonate 
Solution, 
C.c.  Taken. 
Color  Reaction. 
I   .  .  . 
100 
15 
5 
Dark  garnet. 
2    .   .  . 
20 
Po 
15 
5 
Amber. 
3  •  •  • 
1 
99 
15 
5 
Cherry  red. 
4  .  .  . 
•5 
99"5 
15 
5 
Light  pink  or  peach. 
It  will  be  found,  upon  calculation,  that  in  experiment  No.  4  the 
proportion  of  salicylic  acid  is  1  in  2,083  parts  of  water,  and  this 
was  the  weakest  solution  which  gave  the  reaction. 
It  was  found  that,  in  using  solutions  of  hydrogen  peroxide  of 
