Am.  Jour.  Pharm. 
June,  1894. 
Four  Oak  Barks. 
299 
FOUR  OAK  BARKS  FROM  INDIA. 
By  Henry  Trimble. 
Contribution  from  the  Chemical  Laboratory  of  the  Philadelphia  College  of  Pharmacy. 
No.  136. 
Some  months  ago,  through  the  kindness  of  David  Hooper,  there 
were  received  from  A.  E.  Wild,  in  the  British  service  at  Dehra  Dun, 
India,  the  following  oak  barks : 
Quercus  annulata  (Inai). 
"      incana  (Ban). 
"      dilatata  (Moru). 
"      semicarpifolia  (Karshu). 
After  reserving  samples  of  each  for  cabinet  specimens,  the  amount 
of  material  for  investigation  was  necessarily  small. 
The  bark  from  each  of  the  four  species  was  estimated  for  tannin  by 
the  "  hide  "  method.  The  moisture  was  also  determined  in  each 
case,  so  that  the  results  of  the  tannin  estimations  might  be  stated 
on  the  absolutely  dry  bark,  in  order  to  facilitate  comparison. 
The  results  in  per  cent,  were  as  follows : 
Tannin  in  Tannin  in       Ash  in 
air-dry  absolutely  absolutely 
Species.  bark.  Moisture.       dry  bark.     dry  bark. 
Quercus  annulata,   n*37  6*85  12*20  n'3° 
"       dilatata,  ,  7*40  6*88  7*94  10*02 
"      incana,         ....  22*12  5*31  23*36  11*06 
"      semicarpifolia,  ...  7*99  7*04  8*6o  10  88 
In  order  to  separate  the  tannin  from  the  different  barks  for  the 
purpose  of  more  closely  examining  it,  they  were  reduced  to  powder 
and  exhausted  with  acetone.  The  solvent  was  recovered  by 
distillation. 
The  residues  of  these  acetone  extracts  were  in  all  cases  very 
largely  soluble  in  water,  with  which  they  were  treated  for  the  pur- 
pose of  separating  resin  and  phlobaphene.  After  filtration,  acetic 
ether  was  used  to  remove  the  tannin,  but  only  in  the  case  of  the 
the  bark  from  Q.  semicarpifolia  was  there  a  notable  residue  left 
upon  the  evaporation  of  the  solvent. 
These  residues  were  treated  with  water,  the  solutions  filtered  and 
agitated  with  acetic  ether,  which  again  removed  the  tannin.  This 
process  was  repeated  until  the  tannin  was  completely  soluble  in  water. 
On  account  of  the  small  amount  of  bark  and  the  readiness  with 
which  the  tannin  changed  to  anhydride,  the  former  could  not  be 
obtained  from  the  first  three  species  in  a  state  of  purity  to  warrant 
ultimate  analysis.    Attempts  to  prepare  it  purer  by  other  methods 
