234 
Syrup  of  Tolu. 
Am.  Jour.  Pharm. 
May,  1887. 
SYRUP  OF  TOLU  BY  A  NEW  PROCESS. 1 
By  Frederick  Stephenson. 
There  are  various  published  formulae  for  the  preparation  of  this 
syrup,  the  more  important  of  which  are  as  follows : — 
1.  The  B.  P.  formula  in  which  the  balsam  is  ordered  to  be  boiled 
with  water  for  half  an  hour  in  a  lightly  covered  vessel,  filtered  when 
cold,  and  the  sugar  dissolved  in  the  filtrate  by  the  aid  of  heat. 
2.  The  former  United  States  Pharmacopoeia  formula,  in  which  tinc- 
ture of  tolu  is  rubbed  up  with  the  carbonate  of  magnesia,  a  little  sugar 
and  water,  filtered,  and  the  sugar  dissolved  in  the  filtrate  by  the  aid  of 
the  heat. 
3.  In  the  French  Codex  the  balsam  is  ordered  to  be  digested  for 
two  hours  with  one  half  of  the  water  at  the  temperature  of  a  water 
bath.  It  is  then  re-digested  with  the  other  half  in  the  same  way,  the 
mixed  liquids  cooled,  filtered,  and  the  sugar  dissolved  by  the  heat. 
4.  In  the  1883  United  States  Pharmacopoeia  the  balsam,  sugar  and 
water  are  ordered  to  be  digested  in  a  covered  vessel  for  two  hours  at  a 
temperature  not  exceeding  180°  F.,  and  strained  through  a  wetted 
muslin  strainer  when  cold. 
The  chief  object  to  be  aimed  at  in  syrup  of  tolu  appears  to  be  to  se- 
cure the  full  flavor  of  the  balsam  which  is  said  to  be  due  to  tolene, 
cinnamate  of  benzyl  and  benzoate  of  benzyl,  all  of  which  are  volatile 
liquids.  It  also  contains  doubtless  small  quantities  of  cinnamic  and 
benzoic  acids,  but  these  do  not  appear  to  be  of  primary  importance. 
On  this  account  all  the  above  formulae  strike  one  as  more  or  less  faulty. 
Any  one  who  has  made  the  syrup  by  the  first  process  must  have  felt 
that  the  boiling  caused  a  considerable  loss  of  volatile  odorous  prin- 
ciples. The  second  process  is  also  faulty  for  the  reason  that  the  car- 
bonate of  magnesia  retains  some  of  the  volatile  constituents  as  well  as 
cinnamic  and  benzoic  acids.  It  also  renders  the  syrup  slightly  alkaline 
and,  therefore,  incompatible  with  alkaloidal  salts. 
The  third  and  fourth  formulae,  though  perhaps  a  slight  improve- 
ment on  the  first,  are  still  open  to  the  objection  of  employing  too  much 
heat.  For  the  fourth  process  the  advantage  is  claimed  that  the  sugar 
aids  solution  of  the  aromatic  principles,  but  it  is  open  to  the  objection 
that  a  strong  syrup  is  very  difficult  to  filter  bright. 
1  Read  before  the  Pharmaceutical  Society  of  Great  Britain  at  an  Evening 
Meeting  in  Edinburgh,  Wednesday,  March  16. 
