396  Balsam  Copaiba  vs.  Gurjun  Balsam.  {Am£^x™gm' 
agitating  the  mixture  well,  then  suspending  the  test  tube  in  boiling 
water  until  the  contents  begin  to  boil ;  paraffin  oil,  if  present,  will 
separate  from  the  mixture  and  sink  to  the  bottom,  while  the  balsam 
is  held  in  solution  or  in  suspension  by  the  alcohol. 
Gurjun  Balsam. — Hager's  test  is  as  follows  :  To  3  c.c.  of  a  mix- 
ture of  1  part  of  sulphuric  acid  and  25  parts  of  pure  acetic  ether, 
add  6  drops  of  the  balsam  ;  after  a  few  minutes  the  mixture  will 
assume  a  violet  hue,  if  a  large  per  cent,  of  gurjun  balsam  is  present, 
and  on  standing  twelve  hours  it  will  change  to  a  dark  brown  or 
black  color. 
A  second  test  is  as  follows  :  Dissolve  1  drop  of  the  balsam,  to 
be  tested,  in  20  drops  of  carbon  disulphide  ;  to  this  mixture  add  1 
drop  of  a  cooled  mixture  of  equal  parts  of  sulphuric  and  nitric  acids  ; 
mix  well.  If  gurjun  balsam  is  present  a  red  or  violet  tinge  will 
appear. 
Glacial  Acetic  Acid  Test,  due  to  Messrs.  Dodge  and  Olcott, 
is  executed  thus  :  Place  1  c.c.  of  glacial  acetic  acid  (99-5  per  cent.) 
into  a  test  tube  ;  to  this  add  4  drops  of  pure,  concentrated  nitric 
acid  (i"42),  mix  well  ;  then  add  to  this  mixture,  carefully,  4  drops  of 
the  balsam  in  question;  if  gurjun  balsam  is  present,  a  reddish  zone 
will  be  formed  between  the  layer  of  balsam  and  the  acid  mixture  in 
a  few  minutes.  On  mixing  the  contents  of  the  test  tube  well,  the 
whole  will  assume  a  reddish  or  purple  color.  The  degree  of  color 
varies  with  the  amount  of  gurjun  balsam  present. 
Acid  Number. — A  weighed  portion  of  the  balsam  is  dissolved  in 
alcohol,  a  few  drops  of  phenolphthalein  solution  added,  and  titrated 
with  as  eminormal  solution  of  caustic  potash.  The  number  of  mgms. 
of  potassium  hydroxide  required  to  neutralize  I  gramme  of  the 
balsam  is  called  the  acid  number. 
The  Ammonia  Tests. — All  varieties  of  balsam  copaiba,  except 
para,  when  mixed  with  an  equal  volume  of  10  per  cent,  ammonia 
water,  will  form  a  clear,  transparent  solution,  more  readily  when 
warmed.  Again,  when  1  part  of  the  balsam  is  mixed  with  10  parts 
of  10  per  cent,  ammonia  water,  the  resulting  mixture  should  neither 
gelatinize  nor  separate  a  gelatinous  substance,  even  after  standing  a 
day. 
The  accompanying  table  contains  the  results  of  the  examination 
of  the  samples  secured,  as  well  as  a  few  samples  of  pure  balsam 
copaiba,  adulterated  by  myself  with  gurjun  balsam. 
