Am.  Jour.  Pharm. 
July,  1896. 
Powdered  Gamboge. 
373 
liquid  collected  will  contain  an  abundance  of  starch.  Upon  these 
facts  the  following  test  is  based  :  in  5  c.c.  of  potassa  solution,  I  gm. 
of  powdered  gamboge  is  dissolved  with  stirring  ;  then  45  c.c.  of 
distilled  water  are  added,  and  lastly  an  excess  of  hydrochloric  acid, 
the  whole  being  stirred  until  uniformly  of  a  bright  yellow  color. 
The  thin  magma  so  obtained  is  poured  upon  a  pellet  of  absorbent 
cotton  loosely  inserted  into  the  neck  of  a  small  funnel.  The  almost 
colorless  liquid  which  drains  off  is  tested  with  a  drop  or  two  of 
iodine  solution.  If  starch  is  present  in  quantities  larger  than  2 
per  cent.,  a  dark  blue  color  or  precipitate  is  immediately  produced. 
Commercial  powdered  gamboge  generally  gives  a  greenish  tinge, 
gradually  developing  a  faint  blue  color. 
Pure  gamboge,  with  1  per  cent,  of  starch  or  flour,  gives  a  faint 
blue,  becoming  darker  on  standing  and  depositing  a  slight  pre- 
cipitate. 
Two  per  cent,  of  starch  gives  immediately  a  decided  blue,  and,  on 
standing  a  few  hours,  some  precipitate. 
Five  and  ten  per  cent,  of  starch  give  almost  immediately  decided 
precipitates  of  iodide  of  starch. 
Five  per  cent,  and  less  of  curcuma  gives  pronounced  starch 
reactions. 
Any  powdered  gamboge  which,  by  this  test,  gives  immediately  a 
dark  blue  color  or  precipitate,  should  be  looked  upon  with  suspicion. 
But  even  if  the  drug  were  perfectly  free  from  starch,  it  might  still 
be  grossly  adulterated.  So  the  only  criterion  of  its  value  is  the 
presence  of  the  proper  amount  of  resin.  What  the  remainder  con- 
sists of  is  medicinally  of  no  importance,  so  long  as  it  is  inert. 
In  the  short  table  following,  is  given  the  amount  of  resin  and 
residue  obtained  from  several  varieties  of  gamboge  by  treatment 
with  alcohol.  Moisture  was  not  estimated,  the  material  being  taken 
in  the  air-dry  condition  : 
Sample.            Pipe  No.  i.  Pipe  No.  2.  Pipe  No.  3.  Powdered. 
Residue  ....  2i'i                   23*46  24/1  i8'6 
Resin  78-9                  76*54  75-9  81*4 
Starch   ....  none                   none  none  trace 
The  starch  test,  as  above  applied,  can  be  used  with  advantage  in 
the  examination  of  other  powdered  drugs,  straining  being  resorted 
to  only  where  there  is  an  insoluble  portion  or  a  precipitate  which 
interferes  with  observation  of  color. 
