296  Disinfection  with  Formaldehyde.    { ArnA^X 
destroyed  in  the  reduction  of  KC1Q3  to  KC1  was  then  calculated 
from  the  reaction 
2KC103  +  3HCHO  =  2KCI  +  3C02  +  3H20. 
The  results  of  these  tests  are  shown  in  the  following  table.  It  is  to 
be  noted  that  if  the  reaction 
KCIO3  +  3HCHO  =  KC1  +  3HCOOH 
is  assumed,  the  calculated  amounts  of  formaldehyde  consumed  will 
be  just  twice  those  given  in  the  table. 
Tests  of  Residue  Remaining  after  Reaction  between  Formalin  and  Potassium 
C  III  orate. 
Test 
No. 
KCIO3  Used, 
Grams. 
Formalin 
Used, 
Grams. 
Calc.  KClOg  Re- 
duced, Grams. 
HCHO  Oxidized 
(Equiv  to  KC1 
Found),  Grams. 
Formalin  (40%) 
Equiv.  to  HCHO 
Oxidized,  Grams. 
1 
12 
3-917 
1-439 
3-59 
2 
6 
12 
3.817 
1.402 
350 
3 
6 
12 
3.62O 
1.329 
3-33 
4 
5 
12 
3.750 
1-375 
3-44 
5 
t* 
3.726 
1.369 
3-42 
6 
1 
12 
2.99O 
1.098 
2.75 
7 
2 
12 
2.010 
0.738 
1.85 
In  Tests  5  and  6  a  very  small  amount  of  liquid  remained  in  the 
residue  after  the  reaction  ;  in  Test  7  an  appreciable  amount  of  liquid 
remained  and  a  determination  of  formaldehyde  showed  1.104  Gm. 
HCHO,  equal  to  2.76  G.  of  40  per  cent,  formalin.  In  Tests  1  to  5, 
inclusive,  where  the  weight  of  KC103  was  at  least  one  third  of  the 
weight  of  the  formalin,  the  amount  of  HCHO  oxidized  was  fairly 
constant,  the  KC1  found  indicating  that  only  part  of  the  KC103  had 
been  reduced.  In  Tests  6  and  7  the  excess  of  formalin  was  such 
that  practically  complete  reduction  of  the  chlorate  was  effected  and 
the  amount  of  formalin  oxidized  much  less. 
A  number  of  qualitative  tests  were  made  using  formalin  and 
sodium  chlorate  in  proportions  varying  from  6:1  to  2:1,  the  maxi- 
mum temperatures  reached  during  the  reaction  being  noted.  With 
the  ratios  2:1,  2.5:1,  and  3:1.  this  temperature  was  108-1090  C, 
while  with  lower  proportions  of  chlorate  (4:1  and  6:1)  the  tem- 
perature was  slightly  less,  1040  to  105°  C.  In  each  case  the  reac- 
tion started  at  60-65 0  C.,  was  violent  at  about  75°  C,  and  lasted 
only  about  30  seconds,  the  maximum  temperature  being  indicated 
near  the  end  of  the  reaction. 
