300 
Testing  o  f  Per  u  Balsam. 
J  Am.  Jour.  Pharm. 
i      June,  1881. 
The  free  ciiinaniic  acid  can  thus  be  employed  qualitatively  and 
quantitatively  as  a  criterion  of  the  purity  of  Peru  balsam,  but  too 
much  importance  should  not  be  attached  thereto.  This  acid  is  not  to 
be  regarded,  like  the  cinnamein,  as  an  active  constituent,  and,  on  the 
other  hand,  does  not  occur  to  such  an  amount  in  the  balsam  as  to  be 
regarded,  like  the  black  resin,  as  a  peculiar  indicative  portion  of  the 
mixture.  As  the  free  acid  always  amounts  to  but  a  few  per  cent.,  the 
percentage  amount  would  be  but  little  changed  even  by  a  large  adul- 
teration, excejit  in  so  far  as  benzoin  is  concerned,  in  which  case  readily- 
perceptible  large  amounts  of  benzoic  or  cinnamic  acids  would  be  intro- 
duced. A  large  admixture  of  storax,  on  the  contrary,  produced,  to 
the  author's  astonishment,  no  correspondingly  increased  yield  of  cin- 
namic acid. 
In  comparison  with  most  materials  which  are  adapted  to  its  adultera- 
tion, the  somewhat  slighter  tendency  of  Peru  balsam  to  decomposition 
by  the  action  of  alkalies  appears  to  be  of  service.  This  peculiarity  has 
already  been  indicated  by  Dr.  Grote,  as  he  (^^  Pharm.  Centralh.,''  May 
27,  1880,  p.  179)  recommended  3  to  6  drops  of  the  balsam,  i.  e.,  about 
a  quarter  cubic  centimeter,  to  be  shaken  with  2  to  3  cubic  centimeters 
of  ammonia,  sp.  gr.  0*960,  or,  according  to  the  relations  by  weight,  2 
parts  of  balsam  witli  about  17  parts  of  ammonia.  The  free  acid  passes 
into  solution,  and  of  the  remaining  constituents  only  a  small  amount 
is  emulsionized,  while  the  chief  portion  is  not  at  all  further  changed. 
From  the  pure  balsam,  after  one  day,  a  turbid  liquid  may  be  decanted, 
while  the  residue  remains  semi-liquid,  or  very  soft;  but  little  is  here 
dependent  upon  the  proportions,  as  it  was  found  that  the  balsam  shows 
still  the  same  behavior  when  it  is  shaken  with  only  half  its  weight  of 
ammonia.  The  action  of  ammonia  upon  adulterated  balsam,  however, 
is  quite  different;  they  solidify  after  a  short  time,  as  Dr.  Grote  has 
shown,  to  a  stiff  jelly,  from  which  no  liquid  can  be  decanted,  or  they 
become  perfectly  hard.  Dr.  Grote  has,  however,  already  indicated 
that  it  is  chiefly  colophony  which  may  be  detected  in  this  manner,  and 
that  other  admixtures,  on  the  contrary,  such  as  benzoin,  storax,  copaiba 
and  gardschan  balsam  (wood  oil)  cannot  be  recognized  by  means  of 
ammonia.  The  same  is  applicable  to  the  fatty  oils,  although  the 
adulterators  will  scarcely  make  use  any  longer  of  castor  and  other  oils, 
as  these  can  be  much  too  easily  detected.  Castor  oil,  one  of  the 
heaviest,  has  the  specific  gravity  0*96,  and  ftiust,  therefore,  sensibly 
affect  the  specific  gravity  of  the  balsam.    If  the  balsam  containing  fat 
