THE  AMERICAN 
JOURNAL  OF  PHARMACY 
DECEMBER,  iqoj 
BENZOIC  VS.  CINNAMIC  ACID  IN  FOOD  ANALYSIS. 
By  Wilbur  h.  Scovii^e. 
An  indictment  was  recently  served  in  Massachusetts  against  a 
prominent  firm  for  selling  sweet  pickles  which  were  said  to  be  pre- 
served with  benzoic  acid.  Both  the  Government  chemist  and  the 
chemist  to  whom  the  sealed  samples  were  taken,  said  that  benzoic 
acid  was  present.  The  manufacturer  denied  this  strenuously,  and 
asked  for  an  investigation  by  the  writer,  which  investigation  brought 
out  the  following  facts  : 
The  pickles  were  highly  flavored,  oils  of  cinnamon  and  clove 
being  the  chief  flavoring  agents.  Oil  of  cinnamon  (cassia)  is  com- 
posed chiefly  of  cinnamic  aldehyde,  which  oxidizes  on  exposure  to 
cinnamic  acid.  Old  oils  of  cinnamon  may  be  found  containing 
abundant  crystals  of  this  acid. 
Cinnamic  acid  resembles  benzoic  acid  closely,  both  in  physical 
and  chemical  properties.  So  close  is  the  resemblance  that  in  the 
early  part  of  the  nineteenth  century  the  two  acids  were  confounded, 
and  until  Bizio,  in  1826,  showed  that  cinnamic  acid  is  a  distinct 
substance,  it  was  identified  with  benzoic  acid. 
The  resemblance  between  the  two  acids  appears  to  have  been 
overlooked  in  the  above  case. 
For  the  detection  and  identification  of  benzoic  acid  two  tests  have 
been  adopted  by  Government  chemists.  These  are  (ij  the  ferric 
chloride  test,  which  gives  a  flesh-colored  precipitate  with  neutral 
benzoates,  and  (2)  the  metadinitrobenzoic  acid  test,  which  consists 
in  heating  the  dry  substance  (after  separation  from  other  material) 
with  strong  sulphuric  acid  and  a  little  potassium  nitrate,  neutralizing 
(549) 
