Am.  Jour.  Pharm.) 
April,  1910.  f 
Correspondence. 
195 
ated  with  a  definite  volume — weight  in  case  of  German  and  French 
Pharmacopoeias — of  menstruum,  the  mixture  strained,  and  marc 
expressed,  the  liquids  then  mixed  and  filtered.  There  is  no  allow- 
ance made  for  increase  in  volume  through  the  dissolved  extractive 
matter.  The  finished  preparations  are  therefore  neither  of  known 
percentage  or  part  solutions.  The  U.  S.  Pharmacopceial  method 
avoids  this,  perhaps  slight,  inaccuracy. 
There  are  a  few  points  in  the  various  pharmacopoeias,  regarding 
maceration  and  percolation  which  seem  inconsistent  to  me,  although, 
I  grant,  that  there  may  be  good  reasons,  which  do  not  appear 
on  the  surface.  I  do  not  understand  why  the  British  authority 
directs  compound  tincture  of  cinchona  to  be  prepared  by  percolation 
and  compound  tincture  of  gentian  by  maceration ;  nor  do  I  com- 
prehend why  the  British  Pharmacopoeia  as  well  as  the  German  auth- 
ority directs  fluidextracts,  which  represent  a  much  larger  proportion 
of  drug  than  do  the  tinctures,  to  be  prepared  by  percolation,  while 
some  of  the  British  and  all  of  the  German  tinctures  are  prepared 
by  maceration. 
There  are  several  tinctures  directed  to  be  prepared  by  macera- 
tion by  the  U.  S.  Pharmacopoeia,  which,  although  I  have  heard 
reasons  given  for  so  doing,  in  accordance  with  my  experience  would 
be  better  prepared  by  percolation. 
I  find  the  process  of  maceration  entirely  unsatisfactory  for  the 
preparation  of  tincture  of  arnica,  inasmuch  as  the  drug  acts  much 
like  a  sponge,  absorbing  by  far  the  greater  portion  of  the  menstruum 
with  which  it  is  macerated,  and  it  is  a  very  difficult  proposition 
to  express  much  of  the  adhering  liquid,  even  by  means  of  a  "  press." 
Besides  the  filtered  tincture  is  not  so  clear  and  rich  in  color  as 
that  prepared  by  percolation.  I  might  mention  that  I  have  fre- 
quently observed  that  in  passing  menstruum  through  a  drug 
the  latter  while  being  extracted  acts  as  a  clarifying  agent.  In 
regard  to  the  best  method  for  the  preparation  of  this  tincture  and 
other  tinctures  presenting  similar  difficulties,  I  recommend  for 
consideration  the  English  method  of  collecting  a  large  portion  of 
the  required  volume  as  a  reserve  percolate  and  then  expressing  the 
marc.  I  make  this  suggestion  only  in  case  a  dreg  still  is  not  at 
hand  or  the  fluid  cannot  be  forced  from  the  marc  by  water  (I  have 
rarely  found  this  latter  suggestion  expedient). 
I  have  recently  had  under  observation  a  series  of  experiments 
with  different  processes  for  the  preparation  of  compound  tincture 
