Am  April*  fgijr"11"  )       Determination  of  Phenacetin.  157 
also  upon  the  facts  that  phenacetin  is  soluble  in  methyl  alcohol  and 
the  addition  of  nitric  acid  to  such  a  solution  properly  diluted  gives  a 
yellow  color,  the  intensity  of  which  is  used  as  a  measure  of  the 
phenacetin  present  by  comparison  in  Nessler  tubes  with  standards. 
Standards  are  prepared  as  follows  :  A  standard  solution  is  made 
by  dissolving  .500  g.  of  phenacetin  in  sufficient  methyl  alcohol2  to 
make  100  mils ;  one  mil  of  this  solution  then  contains  .005  g.  of 
phenacetin. 
Tube  A  —  1  mil  of  st.  sol.  -f-  4  mils  methyl  alcohol  =  .005  g,  phenacetin 
Tube  B  —  2  mils  of  st.  sol.  +  3  mils  methyl  alcohol  =  .010  g.  phenacetin 
Tube  C  —  3  mils  of  st.  sol.  -f-  2  mils  methyl  alcohol  =  .015  g.  phenacetin 
Tube  D  —  4  mils  of  st.  sol.  -f-  1  mil  methyl  alcohol  =  .020  g.  phenacetin 
Tube  E  —  5  mils  of  st.  sol.  +  methyl  alcohol  =  .025  g.  phenacetin 
To  each  tube  except  the  last,  methyl  alcohol  is  added  as  indi- 
cated, in  order  to  have  an  equal  amount  in  each  tube,3  then  5  mils  of 
water  and  3  mils  of  concentrated  nitric  acid  is  added  to  each  tube.4 
A  qualitative  test  is  made  on  the  sample  and  this  gives  an  idea 
as  to  the  amount  of  phenacetin  present.  A  definite  amount  of  the 
sample  is  dissolved  in  methyl  alcohol,  so  that  one  mil  of  the  solution 
will  contain  between  .005  g.  and  .025  g.  of  phenacetin.  Portions  of 
this  solution  are  then  measured  into  Nessler  tubes  and  treated  the 
same  as  the  standards  all  of  which  must  be  made  at  the  same  time. 
After  an  elapse  of  5  minutes  make  up  the  volume  in  each  tube  to  50 
or  100  mils  and  compare  the  intensity  of  color  in  the  tubes  containing 
the  sample,  with  the  color  produced  in  the  tubes  containing  the  stand- 
ards until  two  are  found  (one  standard  and  one  unknown)  that 
correspond.  Computations  are  then  made  using  the  standard  tube  as 
a  basis. 
Chemical  Laboratory, 
Department  of  Health,  City  of  New  York. 
2  Pure  methyl  alcohol  is  used  (reagent) . 
3  This  is  necessary  because  the  methyl  alcohol  decreases  the  intensity  of 
color  produced. 
4  It  is  preferable  to  use  a  burette  to  measure  the  nitric  acid. 
