ON  BENZOIC  ACID  FROM  URINE. 
23 
ON  BENZOIC  ACID  FROM  URINE. 
BY  THE  EDITOR. 
Within  a  few  years  past,  and  since  the  discovery  of  the  ready 
conversion  of  hippuric  into  benzoic  acid,  there  have  been  occa- 
sional importations  of  benzoic  acid  from  Germany,  derived  from  the 
urine  of  horses  and  cattle,  and  that  which  we  have  seen  has  been 
beautifully  brilliant  in  its  lustre  and  whiteness.  Hippuric  acid 
appears  to  be  proximately  composed  of  benzoic  acid  and  gly- 
cocoll,  (or  sugar  of  gelatin),  and  may  be  decomposed  into  these 
bodies  by  the  action  of  strong  acids.  For  instance,  when  hip- 
puric acid  is  boiled  in  strong  muriatic  acid,  the  acid  combines 
with  the  glycocoll,  and  liberates  the  benzoic  acid,  which  precipi- 
tates in  crystals  by  the  cooling  of  the  solution.  Or  the  glyco- 
coll may  be  destroyed  by  oxydizing  agents,  and  the  acid  thus 
set  at  liberty  ;  01%  finally,  it  may  be  obtained  directly  from  the 
urine  of  the  cow  or  horse  by  suffering  that  fluid  to  putrefy, 
when  the  glycocoll  base  of  the  hippuric  acid  is  destroyed,  and 
by  concentration  the  benzoic  acid  crystallizes  out.  It  is  pro- 
bable that  the  acid  made  by  the  latter  process  is  liable  to  be 
tainted  with  an  unpleasant  urinous  odor,  (not  observable  when 
the  urine  is  evaporated  whilst  fresh,  and  precipitated  with  muri- 
atic acid,)  when  not  carefully  purified. 
Recently  a  lot  of  benzoic  acid  having  this  peculiarity  arrived 
at  the  New  York  Custom  House  from  a  German  port,  and  has 
been  rejected  on  the  ground  that  it  is  not  derived  from  gum 
benzoin,  but  is  made  from  urine,  of  which  fact  its  odor  would  lead 
to  suspicion.  Now  it  is  well  known  that  much  of  this  acid  has 
heretofore  passed  unquestioned,  and  was  in  reality  purer  than 
much  of  the  commercial  benzoic  acid  from  benzoin — the  latter 
having  empyreumatic  oil  adhering,  which  gives  it  a  strong  but 
rather  agreeable  odor.  It  becomes  an  interesting  question 
whether  our  examiners  are  justified  in  rejecting  a  chemical  sub- 
stance because  it  is  derived  from  a  different  source  from  that 
usually  indicated  in  books,  or  acted  on  in  practice,  Undoubtedly, 
if  the  benzoic  acid  in  question  is  condemned  on  the  ground  that 
it  has  not  been  properly  purified  from  animal  matter  which,  in 
the  opinion  of  the  examiner,  renders  it  unfit  for  medical  use,  he 
is  correct ;  but  if  no  such  cause  of  unfitness  exists,  and  the 
acid  is  pure,  we  cannot  understand  on  what  just  grounds  it 
