Am.  Jour.  Pharm.) 
January,  1908.  J 
Tests  for  Gurjun  Balsam  in  Copaiba. 
13 
contribution  from  the  laboratory  of  Dodge  &  Olcott,  and  the  test 
was  made  as  follows  (see  proceedings  A.  Ph.  A.,  1896,  page  628)  : 
Four  drops  of  the  sample  are  dissolved  in  15  c.c.  of  glacial 
acetic  acid,  and  to  the  solution  is  added  from  4  to  6  drops  of  C.  P. 
nitric  acid.  With  pure  copaiba,  no  color,  and  at  most  but  a  slightly 
cloudy  solution  results — whereas  with  pure  Gurjun  balsam  a  deep 
purple  color  ensues.  With  mixtures  the.  purple  color  is  supposed 
to  correspond  to  the  extent  to  which  Gurjun  balsam  has  replaced 
copaiba.  According  to  the  authors,  as  little  as  2  per  cent,  of  Gur- 
jun balsam  can  be  detected.  My  experience  with  the  test  indicates 
that  it  is  really  the  most  satisfactory  of  the  old  modifications  of  the 
test,  but  time  is  required  for  the  development  of  the  color  if  only 
small  amounts  of  Gurjun  balsam  be  present. 
I  will  proceed  to  demonstrate  the  test,  using  a  pure  balsam 
copaiba  and  pure  Gurjun  balsam  as  well  as  mixtures  of  the  two  in 
varying  proportions.  Every  precaution  has  been  taken  to  insure 
the  purity  of  the  balsam  copaiba  used.  The  sample  answers  all  the 
U.S.P.  tests  for  purity,  has  a  specific  gravity  of  0-984  at  22°  C.,  leaves 
a  residue  of  53  per  cent,  when  heated  for  48  hours  on  a  water  bath, 
and  requires  2j£  c.c.  of  N/2  alcoholic  potassium  hydroxide  solution 
for  each  gram,  indicating  the  proper  proportion  of  acid  resin.  The 
Gurjun  balsam  has  a  specific  gravity  of  0.96  at  22°  C.,  and  was 
further  distinguished  from  the  similar  Chinese  wood  oil  by  means 
of  the  Elaidin  reaction.  A  time  limit  of  six  hours  or  overnight 
should  have  been  added  to  this  test,  but  time-limit  tests  are  incon- 
venient in  many  ways,  and  when  the  eighth  revision  of  the  U.S.P. 
appeared  it  was  found  to  contain  a  modification  of  this  test  as 
advocated  by  Kebler  (see  proceedings  A.  Ph.  A.,  1896,  page  629.) 
This  test  consisted  in  mixing  four  drops  of  nitric  acid  with  one 
c.c.  of  glacial  acetic  acid  and  adding  four  drops  of  the  sample — 
first  as  an  upper  layer — when  no  reddish  zone  should  appear. 
Further  on  mixing  the  layers  by  shaking,  no  red  or  purple  color 
should  ensue.  No  time-limit  was  set  for  the  development  of  the 
color. 
The  Revision  Committee  was  soon  informed  that  this  test 
was  not  satisfactory  since  with  this  strength  of  nitric  acid  used, 
(about  fifteen  times  that  of  the  original  D.  &  O.  test)  pure  copaiba 
gives  a  dark-brown  coloration  which  obscures  the  red  or  purple 
color  of  the  Gurjun  balsam  reaction  so  as  to  render  it  very  uncer- 
