70 
Peroxide  of  Hydrogen. 
t  Am.  Jour.  Pharm. 
1  February,  1910. 
excess  of  either  sulphuric  acid  or  phosphoric  acid,  inasmuch  as  these 
two  acids  are  not  liable  to  be  acted  upon  by  the  peroxide.  The  use 
of  hydrochloric  acid  or  chlorides  might  lead  to  the  formation  of 
decomposition  products  which  might  render  the  peroxide  injurious. 
The  amount  of  the  excess  of  free  acid  should  in  our  opinion  also 
be  increased  above  what  the  U.S. P.  now  allows,  say  about  double 
the  present  amount,  as  the  present  official  amount  is  soon  reduced 
sufficiently  by  the  alkalinity  of  glass  containers  and  the  shaking- 
experienced  in  transit  to  distant  sections  to  bring  it  below  the  safety 
point,  resulting  in  decomposition  and  blown  corks  very  frequently. 
No  make  that  we  examined  only  a  few  weeks  ago  contained  as  little 
acid  as  the  U.S. P.  allows;  all  of  them  contained  more  and  the  most 
of  them  considerably  more,  though  of  course  in  no  instance  enough 
to  interfere  with  the  usefulness  of  the  product  or  to  cause  any  irrita- 
tion when  used  in  wounds  or  any  other,  sensitive  surfaces.  If  free 
acid  in  sufficient  quantity  will  fully  preserve  peroxide  of  hydrogen 
and  at  the  same  time  in  no  wise  interfere  with  its  usefulness  as  a 
remedial  or  prophylactic  agent,  surely  this  is  the  simplest  way  to 
preserve  it — but  this  will  of  course  have  to  be  shown  and  proven 
by  experiments.  In  our  opinion  the  value  and  desirability  of  acetani- 
lide  as  a  preservative  for  peroxide  solutions  is  open  to  question. 
In  No.  45  of  the  Schweiz.  Wochsch.  faer  Chem.  and  Pharm.,  an 
article  by  Fleissig  appears,  in  which  it  is  stated  that  out  of  eight 
samples  of  peroxide  of  hydrogen  purchased  from  various  German 
and  Swiss  manufacturers,  only  two  showed  an  acidity  below  that 
allowed  by  the  Swiss  Pharmacopoeia,  which  allows  the  same  acidity 
as  the  U.S. P. ;  the  other  six  having  an  acidity  about  three  and  four 
times  higher  than  permitted.  The  author  believes  that  the  official 
amount  of  acid  (0.036  per  cent.)  is  entirely  too  small,  and  that  an 
addition  of  1  to  3  per  cent,  of  acid  should  be  allowed.  This  per- 
centage, however,  we  consider  entirely  too  high,  inasmuch  as  perox- 
ide of  hydrogen'is  frequently  used  for  sterilizing  surgical  instruments 
and  such  a  high  acidity  might  corrode  these. 
Fleissig  further  gives  an  interesting  account  about  the  stability 
of  the  above  peroxide  of  hydrogen  solutions.  He  found  that  after 
two  months'  standing'the  strength  of  two  was  reduced  to  two-thirds 
of  their  original  peroxide  strength,  of  four  to  about  one-half,  and 
of  two  to  less  than  one-quarter  when  kept  in  flint  glass  bottles. 
When  kept  in  amber  bottles,  he  found  that  after  standing  for  eight 
months  the  strength  of  three  was  reduced  to  two-thirds,  of  one  to 
about  one-third  of  its  original  peroxide  strength,  while  four  hardly 
