A  October  1913™'}        Estimation  of  Formaldehyde.  455 
dangerous  to  give  large  doses  of  hexamethylenamine  until  the 
patient  has  first  been  treated  with  small  doses. 
Subsequent  to  the  publication  of  Dr.  Burnam's  paper,  much 
interest  was  evinced  by  the  medical  fraternity  in  the  discovery  of  a 
test  for  the  quantitative  estimation  of  formaldehyde  in  the  urine 
that  would  differentiate  hexamethylenamine  and  yet  would  be  prac- 
ticable in  the  hands  of  the  physician. 
I  offer  the  following  test  to  fill  this  requirement;  from  an  as- 
sayed specimen  of  commercial  formaldehyde  solution,  accurate 
dilutions  are  prepared  of  strengths  1-50,000,  1-100,000,  1-200,000, 
1-300,000,  as  standard  solutions  for  colorimetric  comparison. 
More  standard  solutions  may  be  prepared  if  necessary.  The  test 
will  estimate  quantitatively  up  to  1-500,000  in  the  urine  and 
1-30,000,000  in  clear  water.  Dextrose,  acetone,  acetaldehyde  do 
not  interfere  in  solutions  weaker  than  1-30,000  and  then  only  on 
heating  or  long  standing. 
The  test  is  conducted  as  follows :  To  five  c.c.  of  specimen  con- 
tained in  five-inch  test  tube,  add  .1  c.c.  of  15  per  cent,  solution  of 
sodium  hydroxide  and  mix  well.  Then  add  .1  c.c.  phenylhydrazine, 
base,  not  hydrochloride,  finally  add  .7  grams  of  stick  sodium  hy- 
droxide and  agitate  for  ten  minutes.  The  strength  is  estimated 
colorimetrically  by  comparing  with  the  standard  solutions  treated 
in  same  manner  as  specimen,  and  at  the  same  time.  It  is  important 
to  remember  that  the  several  reagents  must  be  added  to  specimen 
and  standard  solutions  at  the  same  time ;  i.e.,  specimen  and  standard 
are  treated  simultaneously. 
Colorimetric  comparisons  must  be  made  within  twenty  minutes 
after  stick  alkali  is  added.  Usually  comparisons  are  made  in  about 
ten  minutes  subsequent  to  the  addition  of  stick  alkali. 
If  it  is  desired  to  keep  specimens  for  some  hours  previous  to 
estimation,  then  the  .1  c.c.  of  15  per  cent,  solution  of  sodium 
hydroxide  must  be  added.  This  addition  prevents  decomposition 
of  hexamethylenamine  with  production  of  formaldehyde,  which 
will  take  place  in  acid  urine  on  standing.  After  specimen  has  been 
made  alkaline  as  directed  in  method  of  assay,  no  attempt  should 
be  made  to  remove  precipitate,  as  such  procedure  will  remove  free 
formaldehyde  wholly  or  in  part.  In  my  experience  any  attempt 
to  remove  color  of  urine,  by  charcoal,  precipitation,  reduction, 
oxidation,  etc.,  results  in  removal  of  some  or  all  of  free  formal- 
dehyde. 
