12 
Ammonium  Benzoate. 
(Am.  Jour.  Pharm. 
(    January,  1910. 
THE  PHARM ACOPCEIAL  TESTS  FOR  AMMONIUM 
BENZOATE.* 
By  Atherton  Seidell  and  George  A.  Menge, 
Division  of  Pharmacology,  Hygienic  Laboratory,  U.  S.  Public  Health  and 
Marine-Hospital  Service,  Washington,  D.  C. 
The  United  States  Pharmacopoeial  description  of  this  salt  con- 
tains, in  addition  to  the  qualitative  tests  for  ammonia,  benzoic  acid, 
and  certain  common  impurities,  only  two  tests  which  might  be 
expected  to  indicate  the  degree  of  purity  of  the  sample.  These  are 
the  melting  or,  rather,  decomposition  point,  and  the  reaction  towards 
blue  litmus  paper.  The  following  experiments  show  that  neither 
of  these  tests  is  of  any  value  in  determining  the  purity  of  a  given 
sample  of  the  salt.  The  experiments  we  have  made  also  show  that 
the  distillation  method  for  ammonia  determination  is  readily 
applicable  to  the  analysis  of  ammonium  benzoate  samples  and  a 
simple  adaptation  of  this  process  is  therefore  suggested  as  a  quan- 
titative method  for  this  and  similar  Pharmacopoeial  ammonium 
compounds. 
Analysis  of  Ammonium  Benzoate  by  Distillation  of  the  Am- 
monia.— The  distillation  method  modified  to  the  simplest  conditions 
was  found  to  give  entirely  trustworthy  results.  The  details  which 
were  followed  in  the  determinations  reported  herewith  are  as 
follows :  The  distillation  flask  was  an  ordinary  Erlenmeyer  Jena 
glass  flask  of  about  350  c.c.  capacity,  through  the  stopper  of  which 
passed  a  plain  glass  tube  which  was  bent  to  form  an  inverted  U, 
the  longer  arm  of  which  ended  below  the  surface  of  the  standard 
acid  contained  in  the  receiving  flask,  which  was  placed  in  an 
evaporating  dish  containing  cold  water.  The  connections  which 
would  have  been  required  for  a  condenser  were  therefore  elimi- 
nated, and  the  rapidity  of  the  distillation  was  not  appreciably 
affected.  Tenth  normal  solutions  were  used  in  all  cases.  A  con- 
venient amount  of  the  sample  for  a  determination  is  0.5  Gm.  for 
which  50  c.c.  of  0.1  N  H2S04  are  to  be  used  in  the  receiving  flask 
and  50  c.c.  of  0.1  N  caustic  alkali  and  about  150  c.c.  of  water  in 
the  distilling  flask.    About  150  c.c.  of  liquid  are  distilled  over,  and 
*  Presented  in  abstract  at  the  meeting  of  the  Pharmaceutical  Division 
of  the  American  Chemical  Society,  December,  1909. 
