14  Tests  for  Gurjun  Balsam  in  Copaiba.     { A  January Pi908.m' 
tain  with  solutions  containing  as  high  as  30  or  40  per  cent,  of  the 
adulterant.  I  will  proceed  to  show  this  test  with  pure  balsam 
copaiba  and  with  the  mixtures  as  before. 
Realizing  that  the  entire  acid  mixture  was  too  strong,  the  test 
was  changed  with  the  issue  of  Additions  and  Corrections  of  May  I, 
1907,  the  amount  of  nitric  acid  being  cut  from  four  drops  to  one 
drop,  and  the  acetic  acid  being  increased  from  1  c.c.  to  3  cc.'s. 
This  decreased  the  strength  of  nitric  acid  used  by  twelve-fold  and 
approximated  the  strength  used  in  the  original  D.  and  O.  method  ; 
but  the  contact  method  of  applying  the  test  was  retained,  and  so 
with  even  this  improvement,  the  present  official  test  remains  uncer- 
tain. 
I  have  been  informed  on  good  authority  that  chemists  in  certain 
customhouse  laboratories  have  stated  that  they  cannot  apply  the 
test  with  accuracy  to  balsams  containing  less  than  30  per  cent,  of 
Gurjun  Balsam. 
In  a  paper  read  before  the  Pennsylvania  Pharmaceutical  Associa- 
tion last  June,  at  Bedford  Springs,  I  suggested  the  following  modi- 
fication  of  this  test,  which  I  will  endeavor  to  demonstrate. 
Four  drops  of  the  sample  are  dissolved  in  3  c.c.  of  glacial  acetic 
acid  in  a  small  flat-bottomed  cylinder.  T  hree  or  four  drops  of  nitric 
acid  are  then  added  from  a  pipette  in  such  a  way  that  it  mixes  but 
slightly  with  the  solution  of  the  balsam  and  collects  on  the  bottom 
in  a  very  thin  layer. 
Five  per  cent,  seems  to  be  the  limit  of  delicacy  of  this  test  with 
a  five-minute  time  limit.  In  all  these  tests  greater  accuracy  is  al- 
ways to  be  gained  by  comparing  the  results  with  the  test  made 
upon  a  pure  sample. 
Finally,  I  wish  to  show  a  test  which  in  my  laboratory  has  given 
the  most  satisfaction,- — a  test  worked  out  by  Mr.  J.  L.  Turner,  and 
published  in  the  Pharmaceutische  Centralhalle,  volume  48,  No.  21, 
May  23,  1907.  The  test  is  also  described  in  my  paper  above  refer- 
red to.    The  test,  which  I  will  demonstrate,  is  as  follows : — 
Four  drops  of  the  sample  are  dissolved  in  3  cc.'s  of  glacial  acetic 
acid;  one  drop  of  freshly-prepared  10  per  cent,  aqueous  solution  of 
potassium  nitrite  is  added,  and  the  mixture  poured  carefully  on  to 
the  surface  of  2  c.c.  concentrated  sulphuric  acid.  A  dark  color  will 
always  appear  at  the  surface  of  contact,  but  in  the  presence  of  2 
per  cent,  or  more  of  Gurjun  Balsam  a  violet  color  appears  in  the 
clear  upper  layer. 
