AmAprSr  i9ilrm"  }    Disinfection  with  Formaldehyde.  293 
solution  of  formaldehyde  and  a  soluble  chlorate,  and  is  apparently 
analogous  to  the  permanganate  method,  in  that  the  oxidation  of  a 
part  of  the  formaldehyde  furnishes  a  sudden  evolution  of  heat 
which  serves  to  vaporize  the  remainder  of  the  formaldehyde.  It 
was  suggested  to  the  writer  in  the  course  of  analysis  of  a  potassium 
chlorate  explosive.  On  adding  formalin  to  the  water  solution  of 
the  explosive  and  heating  the  mixture,  a  violent  evolution  of  gas 
resulted,  increasing  in  intensity  even  after  the  tube  containing  the 
mixture  was  removed  from  the  flame  of  the  burner.  The  gas 
evolved  was  largely  formaldehyde,  apparently  liberated  from  its  so- 
lution by  the  heat  generated  in  the  oxidation  of  a  part  of  the  for- 
maldehyde by  the  chlorate. 
An  examination  of  the  solution  remaining  after  the  reaction  had 
subsided  showed  the  presence  of  large  amounts  of  chloride  which 
had  resulted  from  reduction  of  the  chlorate.  Repeated  trials  showed 
that  the  violent  evolution  of  gas  resulted  only  from  concentrated 
solutions,  but  that  the  reduction  of  the  chlorate  to  chloride,  with  a 
corresponding  oxidation  of  formaldehyde,  took  place  even  in  the 
case  of  very  dilute  solutions  of  chlorate.  It  has  been  demonstrated 
that  under  proper  conditions  this  reaction  is  quantitative,  and  the 
results  of  the  study  of  this  quantitative  method  for  determining 
chlorates  will  shortly  be  published. 
The  object  of  this  paper  is  merely  to  call  attention  to  what  it  is 
hoped  will  be  a  satisfactory  substitute  for  the  permanganate  method 
of  disinfection,  and  to  offer  an  opportunity  for  a  more  complete 
study  of  the  method,  the  writer's  investigation  having  necessarily 
been  quite  incomplete  because  of  lack  of  time  and  facilities  for  con- 
ducting work  of  this  nature. 
Potassium  permanganate  reacts  immediately  on  coming  in  con- 
tact with  formalin  at  ordinary  temperatures,  and  if  the  permanga- 
nate is  finely  powdered  instead  of  crystalline,  the  reaction  may  be 
violently  explosive  in  character.3  If  formalin  is  poured  on  crystals 
of  sodium  or  potassium  chlorate,  no  action  results  until  the  mixture 
is  warmed  by  application  of  external  heat  to  about  65 0  C.  This 
may  be  considered  as  a  disadvantage,  but  as  a  matter  of  fact  the 
reaction  may  be  started  with  very  little  difficulty.  The  chlorate 
and  formalin  are  placed  together  in  a  suitable  metal  container,  such 
as  a  water  bucket,  of  sufficient  size  to  prevent  the  reaction  mixture 
from  foaming  over,  and  the  bucket,  properly  weighted  so  it  will  not 
3  G.  B.  Frankforter  and  R.  M.  West,  /.  Am.  Chem.  Soc,  28  (1906),  1234. 
