Am  jour.  Pharm.  \         Estimation  of  Phenacetin.  ^4.1 
April,  1919.       >  •  ~\ 
purification,  but  phosphorus  is  materially  reduced.  Chlorides  are 
seemingly  entirely  removed. 
3.  Aqueous  solutions  of  pepsin,  after  purification,  show  no  ma- 
terial change  in  optical  activity.  A  sample  of  high  digestive  power 
( 1  : 40,000) ,  shows  a  reaction  very  nearly  neutral. 
4.  Pepsin  tends  to  approach  nearer  to  the  actual  character  of  a 
protein  (possibly  a  glycoprotein)  with  increasing  proteolytic  activity. 
Detroit,  Michigan. 
THE  ESTIMATION  OF'  PHENACETIN  AND  OTHER 
PARA-AMINOPHENOL  DERIVATIVES  OF 
HYPOCHLOROUS  ACID.1 
By  A.  D.  Powell. 
The  estimation  of  the  substituted  phentidine  compounds  used  in 
medicine,  either  alone  or  in  admixture  with  other  substances  such 
as  salol  and  caffeine,  has  always  presented  certain  difficulties,  and 
various  methods  have  been  proposed  in  recent  years  for  the  analysis 
of  mixtures  of  these  substances.  Several  of  these  are- based  on  the 
varying  solubilities  of  the  compounds  in  organic  solvents,  a  more 
or  less  complete  separation  being  made,  and  the  separate  substances 
determined  gravimetrically.  Thus,  Seidell2  proposed  a  method  of 
this  type  for  the  estimation  of  acetanilide,  phenacetin,  etc.,  in  "head- 
ache powders."  Emery,  Spencer,  and  Le  Febvre,3  for  the  estima- 
tion of  phenacetin  and  salol,  make  use  of  selective  hydrolysis,  finally 
reconverting  the  phenetidine  to  phenacetin  by  acetylation,  and  weigh- 
ing the  phenacetin  as  such,  the  salol  being  estimated  by  bromine 
absorption.  Another  method  recently  published  by  Salkover4  for 
the  separation  of  these  drugs  depends  on  the  solubility  of  salol  in 
petroleum  ether,  phenacetin  and  acetanilide  being  nearly  insoluble 
in  this  solvent. 
Such  methods  suffer  from  the  obvious  defect  that  they  do  not 
sufficiently  identify  the  substances  present  in  the  mixture,  and  the 
melting-points  of  the  separated  constituents  cannot  always  be  relied 
on.  owing  to  the  separation  not  being  perfect. 
1  Reprinted  from  The  Analyst.  January,  1919. 
-J.  Amer.  Chem.  Soc,  1907,  29.  1 088-1 091 ;  The  Analyst,  1907,  32,  360. 
3/.  hid.  and  Eng.  Chem.,  1915.  5,  681-684:  The  Analyst,  1915,  40,  445. 
4  Amer.  J.  Pharm.,  1916,  88,  484-485:  The  Analyst.  1917.  42,  16. 
