Am.  Jour.  Pharin.  \ 
February,  1910.  J 
Peroxide  of  Hydrogen. 
69 
PEROXIDE  OF  HYDROGEX. 
By  A.  R.  L.  Dohme,  Ph.D.,  and  H.  Exgelhardt,  Ph.D. 
Some  months  ago  an  article  by  Dr.  Francis  appeared  dealing 
with  the  preserving  of  solutions  of  peroxide  of  hydrogen  by  the 
addition  of  a  comparatively  small  amount  of  acetanilide.  As  nearly 
as  the  writers  remember,  it  was  stated  there  that  the  solutions  kept 
well  for  more  than  a  year,  and  that  a  deterioration  did  not  take 
place  after  eleven  months,  as  stated  by  Professor  Coblentz.  We 
have  had  opportunity  frequently  to  examine  samples. of  peroxide  of 
hydrogen  preserved  with  acetanilide  from  different  manufacturers, 
and  in  most  cases  we  found  that  the  preparation  smelled  strongly 
of  nitrobenzene,  showing-  that  a  decomposition  had  taken  place. 
Unfortunately  we  were  not  able  to  learn  the  age  of  the  preparations. 
If  such  a  decomposition  of  the  preserving  agent  takes  place,  the 
value  of  the  addition  of  such  material  should  be  seriously  questioned. 
A  process  of  W.  Heinrici  which  is  covered  by  the  American  Patent 
825  883  to  preserve  peroxide  of  hydrogen  solutions  depends  on  the 
addition  of  amino  derivatives.  Acetanilide,  which  belongs  to  this 
class  of  compounds,  is  used  in  this  country  only,  while  in  Europe 
the  preserving  of  peroxide  of  hydrogen  is  effected  by  other 
chemicals. 
Among  the  preservatives  used,  the  following  may  be  named : 
Renault  and  Lepinois  recommend  the  addition  of  boric  acid.  Allain 
recommends  the  addition  of  about  I  per  cent,  of  sodium  chloride, 
magnesium  chloride,  or  calcium  chloride.  According  to  L.  Martin, 
an  addition  of  0.5  per  cent,  of  borax  preserves  the  peroxide  of  hydro- 
gen satisfactorily,  rendering  it  at  the  same  time  slightly  acid  without 
decreasing  the  titre  of  the  preparation.  From  many  sides,  the  addi- 
tion of  an  excess  of  acid  has  been  recommended,  since  this  addition 
both  preserves  the  peroxide  of  hydrogen  solution  and  neutralizes  the 
alkalinity  of  the  glass.  The  fact  that  acid  exerts  a  good  preserving 
power  on  the  peroxide  of  hydrogen  seems  to  be  acknowledged  by 
most  of  the  manufacturers,  because  we  found  recently  that  samples 
of  nearly  all  the  leading  makes  of  peroxide  solution  prepared  in  this 
country  (about  six  in  all)  of  which  some  had  been  preserved  by 
the  addition  of  acetanilide,  showed  on  examination  an  acidity 
exceeding  that  allowed  by  the  U.S. P.  If  in  future  the  use  of 
acetanilide  for  preserving  peroxide  solutions  should  be  prohibited, 
as  it  should  in  our  opinion,  we  strongly  recommend  the  use  of  an 
