344 
ON  FRACTIONAL  PERCOLATION? 
cession  as  the  second  portion  had  been  percolated  with  the  per- 
colates A.    Finally  obtain — 
18  fluidounces  of  percolate  Reserve  C. 
and  mix  this  with  the  reserves  A  and  B,  previously  obtained. 
By  this  process,  from  the  first  eight  ounces  of  drug  four 
fluid  ounces  of  percolate  are  obtained  for  each  troyounce  of  drug, 
while  from  the  second  portion  of  five  ounces,  nearly  five  fluid- 
ounces,  and  from  the  third  portion  of  three  ounces,  six  fluid- 
ounces  of  percolate  are  obtained  for  each  troyounce  of  drug.  It 
will  also  be  observed  that  the  reserved  percolates  are  so  divided 
as  to  insure  the  use  of  the  weakest  portion  of  each  division 
last.  It  is,  of  course,  necessary  to  pour  on  each  fraction  as 
soon  as  the  one  previously  added  is  absorbed,  but  not  before. 
Whatever  may  be  the  merits  of  these  suggestions  in  improv- 
ing the  present  processes  for  fluid  extracts,  the  above  general 
process  must  be  decidedly  preferable  to  the  present  methods  for 
exhausting  drugs  ;  although,  on  the  other  hand,  it  is  too  com- 
plicated to  find  favor  with  all.  Apart  from  other  considerations 
an  economy  of  menstruum  is  eff*ected,  as  under  no  circumstances 
more  than  three  to  three  and  one-half  pints  of  menstruum  need 
be  used  for  sixteen  troyounces  of  drug ;  for  as  soon  as  the  first 
portion  is  exhausted  it  may  be  expressed,  and  the  liquid  so 
obtained  used  as  so  much  additional  menstruum  for  the  second 
portion ;  and  the  same  is  true  of  the  second  portion  with  rela- 
tion to  the  third.  Finally  all  the  exhausted  material  may,  accor- 
ding to  its  alcoholic  strength,  be  mixed  with  a  suitable  propor- 
tion of  water,  and  expressed ;  and  the  liquid  so  obtained  reserv- 
ed in  a  suitable  vessel  until  sufficient  has  accumulated  to  warrant 
the  expense  of  distillation. 
The  practical  uses  to  which  these  fluid  extracts  could  be  ap- 
plied must  be  obvious  to  every  one.  Many  solid  extracts  that 
are  but  seldom  prescribed  could  be  prepared  from  them  in  such 
quantities  as  might  best  suit  their  consumption.  Most  tinctures, 
ivines  and  syrups  might  be  prepared  for  them  by  processes, 
modified  according  to  the  nature  of  the  drug  or  its  menstruum. 
As  regards  the  menstruum  appropriate  in  each  case,  that  must  be 
regulated,  not  only  by  its  solvent  properties,  but  also  by  its 
power  of  preserving.     It  would  perhaps  not  be  impracticable  to 
