30o 
The  Tannin  of  Cloves. 
Am.  Jour.  Pharm. 
June,  1895. 
THE  TANNIN  OF  CLOVES-* 
By  Wm.  Iy.  Pkabody,  Ph.G. 
Contribution  from  the  Chemical  Laboratory  of  the  Philadelphia  College  of 
Pharmacy.    No.  140. 
The  United  States  Dispensatory  (17th  edition,  page  331)  states 
that  Trommsdorff  found  18  per  cent,  of  tannin  in  cloves.  The 
National  Dispensatory  (5th  edition,  page  417)  states  that  the  same 
investigator  obtained  13  per  cent,  of  tannin,  and  adds,  in  parentheses, 
"which  has  not  been  further  investigated." 
Whether  this  parenthetical  clause  is  an  expression  of  doubt  as  to 
the  occurrence  of  the  principle  in  such  quantity,  or  is  intended  by 
the  editors  of  that  authority  to  direct  attention  to  the  nature  of  the 
tannin  of  this  aromatic  drug,  the  writer  is  not  assured.  So,  in 
order  to  further  investigate  this  matter,  he  procured  and  estimated 
samples  of  powdered  cloves  from  the  cities  named  in  the  tabulated 
results,  and  subsequently  isolated  the  tannin  from  an  authentic  speci- 
men with  the  intention  of  classifying  it. 
The  estimations  were  made  upon  decoction's  prepared  by  com- 
pletely exhausting  twenty  grammes  of  the  powdered  air-dry  sample 
with  hot  water;  when  the  liquid  had  cooled  it  was  mixed  with 
enough  water  to  make  one  litre  and  then  filtered. 
Upon  trial  the  method  of  estimation  which  involves  the  precipi- 
tation of  the  tannin  by  gelatin  in  the  presence  of  alum  was  found  k 
to  be  ill- adapted  for  application  to  cloves,  for  the  reason  that  the 
precipitated  matter  clogged  the  filter  upon  which  it  was  to  be  col- 
lected, to  such  an  extent  that  it  was  feared  decomposition  would 
take  place  before  the  filtration  of  the  mixture  and  the  washing  of 
the  precipitate  could  be  accomplished.  This  process  having  been 
abandoned,  the  plan  of  estimation  tried  next  was  that  known  as  the 
"  Hide-powder  Method,"  and,  as  no  difficulty  was  experienced  in 
the  use  of  it,  this  method  was  accordingly  employed  on  all  of  the 
samples. 
The  application  of  the  process  consisted  in  siphoning  some  of  the 
decoction  through  previously  rasped  raw  hide  contained  in  a  small 
glass  percolator,  which  was  made  to  serve  as  the  short  arm  of  the 
siphon,  it  having  been  inverted  in  a  vessel  containing  the  decoction. 
A  rubber  tube  attached  to  the  neck  of  the  percolator  so  arranged, 
and  leading  into  a  graduated  cylinder,  constituted  the  long  arm  of 
the  apparatus. 
