614 
lamination  of  Balsam  of  Peru. 
f  Am.  Jour  Pharm 
(       Dec,  US-l. 
separate  rea/lily  into  two  layers,  the  lower  of  which  when  sej^arated, 
supersatnrated  with  acetic  acid  and  heated  to  boiling,  should  only  pre- 
sent a  slight  turbidity.  The  separation  of  solid  resin  shows  copaiba 
balsam  or  colophony.  The  former  gives  the  reaction  mentioned  under 
test  4  ;  further,  the  extract  obtained  by  evaporation  of  the  petroleum 
spirit  solution  (test  2)  has  clearly  the  smell  of  oil  of  copaiba,  whilst  a 
colophony  residue  has  no  special  odor. 
Quantitative  Estimation  of  Adulterants. 
(1).  Estimation  of  Benzoin  Admixture. — a.  An  admixture  of  solu- 
'tion  of  benzoin  increases  the  amount  insoluble  in  carbon  bisulphide, 
which  in  the  case  ot  genuine  Peru  balsam  was  never  found  by  the 
author  to  exceed  16  per  cent.,  to  the  extent  of  the  whole  of  the  ben- 
zoin resin,  exclusive  of  the  benzoic^'acid  by  which  it  is  accompanied, 
and  this  may  l^e  used  as  the  basis  of  one  method  of  estimating  the 
extent  of  adulteration  with  benzoin. 
Example. — 1  gram  of  a  mixture  of  equal  parts  of  Peru  balsam  and 
an  alcoholic  solution  of  benzoin  containing  75  per  cent,  of  resin,  when 
treated  with  carbon  bisulphide,  left  a  residue  which,  dried  at  100°  C, 
weighed  0'38  gram.  Of  this  0*08  gram  is  reckoned  as  belonging  to 
the  half  gram  of  Peru  balsam,  and  the  remaining  0*30  gram  as  the 
amount  of  resin  in  the  half  gram  of  benzoin  solution. 
h.  A  second  method  of  estimating  added  benzoin  is  based  upon  the 
amount  of  residue  insoluble  in  ether  after  the  sample  of  balsam  has 
been  treated  with  sulphuric  acid.  The  undissolved  residue  amounts  to 
about  half  the  benzoin  resin  or  one-third  of  the  benzoin  solution. 
Example. — 1  gram  of  a  Peru  balsam  containing  14  per  cent,  of 
benzoin  solution,  after  treatment  with  sulphuric  acid,  left  a  residue  of 
0*05  gram  insoluble  in  ether,  which  represented  10  per  cent,  of 
benzoin. 
c.  The  direct  estimation  of  the  Peru  balsam  in  a  samjile  adulterated 
with  benzoin  may  be  effected  by  re])eatedly  shaking  it  Avith  petroleum 
spirit,  which  dissolves  out  nearly  half  the  Peru  balsam  as  well  as  the 
benzoic  acid  of  the  benzoin.  If  1  gram  of  the  balsam  be  mixed  with 
0*30  gram  of  calcic  hydrate,  and  allowed  to  stand  an  hour,  the  petro- 
leum spirit  then  dissolves  only  41  per  cent,  of  the  balsam  of  Peru 
present,  so  that  the  quantity  of  this  may  easily  be  calculated. 
Example. — From  a  balsam  mixed  with  14  per  cent,  of  benzoin 
solution,  after  maceration  with  calcic  hydrate,  petroleum  spirit  dis- 
