Am.  Jour.  Pharm.  | 
December,  1917.  -> 
Sodium  Benzoate. 
577 
exists,  but  they  lead  to  the  inference  that  the  official  salt  was  in- 
tended to  contain  but  little  water  at  most.  It  can  be  readily  seen 
that  a  variation  of  n  per  cent,  in  strength  is  considerably  beyond 
reasonable  limits,  for  commercial  reasons  as  well  as  for  medicinal 
dosage.  The  British  Pharmacopoeia  of  1914  requires  absence  of 
more  than  4  per  cent,  of  water.  This  a  perfectly  fair  restriction  and 
the  U.  S.  P.  should  have  made  a  similar  specific  provision. 
Experience  has  shown  that  general  provisions,  such  as  that 
rather  effectively  hidden  in  the  Preface  of  the  U.  S.  P.,  permitting 
5  per  cent,  of  moisture  when  no  special  provisions  are  made,  are 
very  liable  to  be  overlooked  by  those  whose  duty  it  is  to  pass  upon 
the  quality  of  medicinal  products. 
The  official  assay  method  does  not  with  certainty  show  whether 
the  salt  actually  contains  the  required  minimum  percentage  of 
benzoic  acid.  It  shows  merely  how  much  alkali  remains  after 
burning  off  the  organic  acid  or  acids  in  combination  with  it  and 
does  not  necessarily  indicate  the  quantity  of  benzoate  present.  A 
direct  determination  of  the  benzoic  acid,  which  is  the.  important  con- 
stituent, is  decidedly  preferable  for  that  reason,  also  because  of 
other  sources  of  error  in  the  method.  It  would  be  quite  possible  to 
adulterate  sodium  benzoate  scientifically  with  sodium  salts  of 
cheaper  organic  acids  in  such  manner  that  the  fraud  would  not  be 
detected  by  means  of  the  U.  S.  P.  tests  alone. 
5  Beekman  Street,  New  York, 
November,  191 7. 
IODOMETRIC  DETERMINATION  OF  CHLORINE  IN 
CHLORIDES.1 
By  Gregory  Torossian. 
With  the  object  in  view  of  determining  chlorine  in  chlorides 
quickly  and  accurately  and  without  the  use  of  silver  nitrate,  the 
well-known  method  for  valuation  of  the  available  Mn02  by  iodine 
was  applied.  In  the  determination  of  the  available  Mn02  by  iodine 
the  sample  is  treated  with  a  quantity  of  hydrochloric  acid  in  a  small 
distilling  flask,  the  liberated  chlorine  is  carried  through  a  glass  tubing 
into  a  solution  of  potassium  iodide  and  the  liberated  iodine  is  titrated 
1  Reprinted  from  The  Journal  of  Industrial  and  Engineering  Chemistry, 
August,  1917. 
