224 
Fluid  Extracts  by  Reper eolation. 
f  Am.  Jour.  Pharm. 
\      Mao,  1878. 
The  deductions  which  the  writer  draws  from  the  work  here  given  as 
applicable  to  the  present  pharmacopoeial  practice,  and  that  which  may 
be  desired  for  the  future  are  mainly  as  follows  : 
First,  that  the  present  formulas  and  processes  for  percolation  are  so 
defective  that  the  relation  to  the  drug  which  they  profess  is  not  prac- 
tically accurate  either  as  to  quality  or  quantity,  and  therefore  that  a 
better  process  is  greatly  needed. 
Second,  that  the  process  by  repercolation,  though  it  has  some  grave 
disadvantages,  and  is  liable  to  defects  in  practice, — yet  gives  far  better 
results  both  in  quality  and  quantity  of  product ;  while  it  is  not  difficult 
in  practice  except  by  comparison  with  the  delusive  simplicity  of  the 
former  processes  ;  and  therefore  that  repercolation  is  better  adapted  to 
pharmacopoeial  use  as  a  model  or  standard  process  than  any  which  has 
yet  been  tried. 
Third,  that  repercolation  may  be  used  on  a  scale  as  small  as  4  or  & 
ounces,  by  great  care  and  skill,  but  is  not  very  successful  with  less  than 
an  avoirdupois  pound  of  material  for  each  percolation. 
Fourth,  that  powders  for  percolation  should  not  be  finer  than  No.  60 
for  hard  compact  substances,  nor  coarser  than  No.  40  for  more  loose 
and  spongy  substances, — with  a  few  special  exceptions. 
Fifth,  that  the  menstruum  should  be  so  adjusted  as  to  dissolve  out 
the  medicinal  principles  with  the  least  practicable  disturbance  of  their 
natural  relations  to  each  other  and  to  the  extractive  matters  whereby 
they  are  rendered  soluble  and  permanent.  Next  that  the  menstruum 
should  contain  the  smallest  practicable  proportion  of  alcohol ;  and 
glycerin  only  when  absolutely  necessary,  as  in  Cinchonas.  And  finally 
that  the  menstruum  should  be  so  adjusted  that  when  the  fluid  extract 
represents  the  drug  weight  for  weight  it  should  also  represent  the  drug 
by  not  less  than  90  minims  to  the  100  grains,  or  more  than  97  minims 
to  the  100  grains,  since  by  repercolation  the  exhaustion  is  never  less 
than  90  per  cent,  and  perhaps  rarely  more  than  97  per  cent,  of  the 
total  soluble  matter. 
Sixth,  that  the  powder  be  moistened  with  as  much  liquid  as  it  can 
be  made  to  hold  and  yet  pass  through  a  No.  8  sieve  ;  that  it  be  not 
tightly  packed  ;  and  that  it  be  well  macerated  before  starting  the 
percolation. 
Seventh,  that  the  rate  of  percolation  be  uniform  and  very  slow. 
At  first,  for  the  reserved  portion,  the  percolate  in  24  hours  should 
