Am  Tour.  Pharm.  \    Evaluation  of  Balsam  of  Tolu. 
Oct.,  1918.        J  '  J 
721 
difficult  owing  to  the  dark  color,  and  to  the  precipitate  which  is 
formed  on  running  in  the  alcoholic  potash.  We  find  it  best  to  pro- 
ceed as  follows : 
Dissolve  5  Gm.  of  the  balsam  in  about  50  Cc.  of  boiling  alcohol, 
add  a  large  quantity  of  phenolphthalein  solution — 3  or  4  Cc. — 
titrate  the  hot  solution  with  normal  alcoholic  potash  until  the  color 
becomes  dark  brown  (but  not  red),  then  attach  to  reflux  condenser, 
boil  up  for  a  few  minutes  in  order  to  break  up  the  precipitate,  and 
finish  the  titration. 
By  this  method  titrations  agree  to  about  0.2  Cc.  N/i  KOH. 
We  append  a  table  of  analytical  data  selected  to  show  the  varia- 
tion from  a  large  number  of  samples  of  balsam  examined  during 
the  last  few  years. 
Excluding  numbers  11  and  12,  which,  from  their  low  content  of 
balsamic  acids,  we  believe  to  have  been  sophisticated,  the  figures 
indicate  a  range  of — 
92.2  to  132.4  for  acid  value, 
59.3  to  90.9  for  ester  value, 
1 54.8  to  206.7  f°r  saponification  value, 
and  32.68  per  cent,  to  47.50  per  cent,  of  total  balsamic  acids. 
The  pharmacopceial  limits  for  acid  value  are  from  107.4  to 
147.2,  and  for  saponification  value  170  to  202. 
Judged  by  these  figures  numbers  3,  4,  6,  7,  8  and  9  would  be  re- 
jected for  low  acid  values :  also  the  saponification  values  of  num- 
bers 6,  7,  8,  9  and  13  lie  outside  the  limits,  although  the  poorest 
of  these  balsams  contain  33.87  per  cent,  of  balsamic  acids.  On  the 
other  hand  numbers  11  and  12,  though  abnormally  low  in  balsamic 
acids,  would  be  admitted  as  genuine. 
We  suggest  that  the  pharmacopceial  limits  be  revised,  that  an  im- 
proved method  for  the  determination  of  the  balsamic  acids  be  in- 
serted, and  also  that  limits  for  ester  value  be  adopted  in  place  of 
those  for  saponification  value.  The  differences  between  the  extreme 
limits  for  acid  value  and  those  for  saponification  value  do  not  co- 
incide with  the  limits  of  the  ester  value. 
The  experimental  work  entailed  by  the  above  has  been  carried 
out  in  the  laboratories  of  the  British  Drug  Houses,  Limited,  under 
the  direction  of  Mr.  C.  A.  Hill,  to  whom  we  are  indebted  for  per- 
mission to  publish  the  results. 
