62  Substitute  for  Potassium  Permanganate.  f  Am-  Jour-  Pharm- 
February,  1915. 
A  SUBSTITUTE  FOR  POTASSIUM  PERMANGANATE  TO 
LIBERATE  FORMALDEHYDE  GAS  FROM  A 
WATER  SOLUTION.1 
By  Samuel  G.  Dixon,  M.D.,  LL.D.,  Commissioner  of  Health,  Commonwealth 
of  Pennsylvania. 
Almost  immediately  after  the  declaration  of  war  by  Germany 
I  requested  the  department's  chemist,  Mr.  Charles  Lawall,  to  proceed 
at  once  to  find  a  substitute  for  potassium  permanganate  that  would 
liberate  formaldehyde  gas  from  a  water  solution  for  the  purpose 
of  disinfecting. 
In  the  literature  no  mention  of  any  other  specific  substance  was 
found  except  in  an  English  patent  application  (4885,  /.  6".  C.  L, 
1908,  p.  915),  where  a  combination  of  sodium  bisulphite  and  formal- 
dehyde solution  was  acted  on  by  potassium  permanganate  or  other 
peracid  salt  and  the  dry  fumigation  formula : 
Formaldehyde,  37  per  cent,  solution   2  parts 
Saturated  alum  sulphate  solution   1  part 
Eight  ounces  of  this  solution  are  used  to  1  pound  of  lime  to 
1000  cubic  feet. 
Dr.  George  Rosengarten  suggested  sodium  dichromate  as  a 
cheap  oxidizing  agent,  and  hydrochloric  acid  to  increase  its  energy. 
Lawall  found  on  experimenting  that  sodium  dichromate  was  more 
energetic  and  satisfactory  in  the  presence  of  sulphuric  acid. 
Numerous  experiments,  confirmed  by  calculations  on  the  relative 
oxidizing  power  of  potassium  permanganate  and  sodium  dichromate, 
and  also  working  out  the  optimum  proportion  of  sulphuric  acid,  led 
to  the  conclusion  that  the  following  proportion  gave  the  best  results, 
which  are  in  every  way  comparable  to  those  with  potassium  perman- 
ganate. 
Sodium  dichromate,  10  ounces  avoirdupois. 
Saturated  solution  of  formaldehyde  gas,  1  pint. 
Sulphuric  acid,  commercial  iV2  fluidounces. 
The  sulphuric  acid  and  formaldehyde  gas  form  a  stable  solu- 
tion. \  This,  after  it  cools,  should  be  poured  over  the  crystals  of 
sodium  dichromate  spread  out  in  a  thin  layer  over  the  bottom  of  a 
vessel  having  ten  times  the  capacity  of  the  volume  of  ingredients 
used. 
1  Jour.  Amer.  Med.  Assoc.,  Sept.  19,  1914,  p.  1025. 
