^"^siSt.^'Sf^™*}     Preparation  of  Hydrogen  Peroxide.  447 
^^o.  6);  and,  lastly,  that  the  U.  S.  P.  (1870)  formula,  containing  a 
little  over  one  per  cent,  free  HNO3  will  give  a  good  product,  losing, 
however,  a  portion  of  the  water  whilst  drying. 
The  commercial  products  analyzed,  resembling  in  composition  Nos.  3 
and  4  of  the  above,  are  very  likely  made  by  using  the  commercial 
water  of  ammonia,  which  is  stronger  than  the  officinal — 10  per  cent, 
of  NH3. 
The  U.  S.  P.  (1870)  product  is  being  examined  in  the  laboratory  by 
a  senior  student  and  for  this  reason  no  specimen  made  strictly  accord- 
ing to  those  directions  was  examined  by  me. 
PREPAEATIOIS^  OF  C.  P.  HYDROGEN  PEROXIDE  FROM 
THE  COMMERCIAL  ARTICLE. 
By  Dr.  Mann. 
Translated  from  Chemiker  Zeitung,  1888,  p.  857. 
The  increased  use  of  this  preparation  as  an  antiseptic  in  wound 
treatments  has  caused  the  study  of  making  a  pure  product.  Th^ 
commercial  article  may  contain  HCl,  HgSO^,  H3PO4,  HF,  AI2O3, 
MgO,  K2O  and  Na20  as  prepared  for  various  purposes ;  generally 
OaO,  derived  from  the  water,  and,  if  carelessly  prepared,  BaO  and 
traces  of  Fe,  Cu,  Pb,  Mn,  etc.  The  following  process  will  remove  all  of 
these,  if  present. 
To  the  commercial  preparation,  containing  about  3  per  cent.  H2O2 
^  per  cent,  of  pure  concentrated  H3PO4  is  added  after  which  the  solu- 
tion is  rendered  exactly  neutral  by  addition  of  Ba  (0H)2.  This  is  the  im- 
portant step  of  the  process  having  for  its  object  the  precipitation  of  the 
phosphates  of  the  heavy  as  well  as  of  the  alkaline-earth  metals.  The  time 
required  for  the  neutralization  should  be  at  least  15  minutes  during 
which  period  the  liquid  should  be  stirred  continuously ;  a  turbidity 
will  occur  and  on  3-5  minutes  standing  the  precipitate  will  deposit, 
frorn  which  the  supernatant  clear  liquid  is  decanted  or  separated  by 
filtration.  The  filtrate  is  poured,  with  continual  agitation,  into  a  cold 
saturated  solution  of  Ba(0H)2,  a  precipitate  of  hydrated  Ba02,  in 
pearly  laminse  readily  separates ;  H2O2  (the  filtrate)  is  added  as  long 
as  a  precipitate  forms,  this,  toward  the  end  of  the  process,  only  takes 
place  on  thorough  stirring  of  the  liquid ;  excess  of  H2O2  should  be 
avoided.  The  precipitate  is  washed  with  distilled  water  by  decan- 
tation  until  only  Ba  can  be  detected  in  the  washings. 
