152 
Acetanilid  and  Phenacetin. 
Am.  Jour.  Pharm. 
April,  1907. 
of  the  same  dye  prepared  from  a  known  quantity  of  freshly  distilled 
anilin.1 
II.  Saponification  of  the  acetanilid  by  means  of  an  alkali ;  distil- 
lation of  acetic  acid  from  the  resulting  acetate,  from  an  acid  solution; 
and  titration  of  the  distillate. 
It  can  readily  be  seen  that  Method  I,  is  too  elaborate  for  practical 
purposes,  and  the  necessity  for  using  a  colorimetric  method  at  the 
end  renders  it  unreliable  to  a  certain  degree.  Moreover,  the  diffi- 
culty of  the  operation  of  diazotizing,  for  which  too  much  skill  cannot 
be  acquired,  renders  the  method  unavailable  to  the  ordinary  analyst. 
There  remains,  therefore,  only  Method  II.  for  convenient  use  in  an 
analytical  laboratory. 
The  method  for  estimating  acetic  acid  in  acetates  by  means  ot 
distillation  of  the  solution  acidified  with  phosphoric  acid  was  origin- 
ally recommended  by  Fresenius.2  Some  years  later  Erdmann  and 
Schultz,3  followed  soon  after  by  Buchka  and  Erk,4  and  by  Schall,5 
applied  this  method,  though  in  form  of  a  less  successful  modification 
(acidulation  with  sulphuric  acid),  to  the  estimation  of  acetic  acid 
split  off  from  acetylized  products  by  means  of  saponification. 
Herzig,6  shortly  after  the  publication  of  Erdmann  and  Schultz's 
work,  made  use  of  phosphoric  acid  in  this  process,  which  thus 
received  erroneously  the  name  of  "  Herzig's  Method."  7 
As  applied  by  the  authors  to  acetanilid,  the  method  can  be  worked 
as  follows  : — 
One  gramme  of  acetanilid  is  saponified  by  heating  to  boiling,  under 
a  reflex  condenser,  for  one  and  a  half  to  two  hours  with  3  grammes 
sodium  hydroxide,  20  c.c.  alcohol,  and  10  c.c.  water.  The  solution 
is  then  transferred  to  an  evaporating  dish  and  the  alcohol  is 
evaporated  off  on  the  water-bath.  The  residue  is  transferred  to  a 
separator  and  shaken  out  once  with  ether  in  order  to  remove  the 
anilin  split  off  from  the  acetanilid.    The  ethereal  solution  is  shaken 
1  Bucherer  and  Schwalbe,  Berichte,  39,  2798. 
2  Zeitschrift  fur  Analytische  Chemie,5  (1866),  315. 
3  L,iebig's  Annalen  der  Chemie  und  Pharmacie,  21Q  (1882),  232. 
4  Berichte,  is  (1885),  11 39. 
5  Berichte,  22  (1889),  1561. 
6  Monatshefte  fur  Chemie,  5  (1884),  90. 
7  H.  A.  Michael,  Berichte,  27  (1894),  2687.  Ciamician,  Berichte,  28  (1895), 
1395- 
