/ 
VACUUM  MACERATION,  ETC.  3 
The  following  is  the  printed  account  of  the  process  received 
from  Dr.  Duffield. 
"  The  drug  ground  to  the  requisite  fineness  is  introduced  into  a  strong 
cylinder,  connected  with  an  air  pump  and  the  air  exhausted  ;  through  a 
syphon  tube  the  requisite  amount  of  menstruum  is  allowed  to  be  sucked 
into  the  vacuum  chamber.  When  we  exhaust  the  air  from  the  tight 
cylinder,  the  pores  of  the  comminuted  drug  give  up  the  air  enclosed  in 
them,  and  when  the  menstruum  is  allowed  to  flow  in,  it  is  forced  into  these 
pores  by  the  pressure  of  the  air  outside.  In  this  way  we  arrive  at  a 
more  perfect  maceration  than  by  any  other  method  heretofore  adopted." 
The  moist  macerated  mass  is  then  subjected  to  pressure  to 
expel  the  absorbed  solution  of  the  soluble  matter  of  the  drug, 
which  is  made  to  measure  a  pint  from  cacn  io  troy  ounces,  by 
experimental  trial  of  the  quantity  ol  menstruum  needed  to 
obtain  that  result. 
We  have  not  tried  this  process,  nor  have  we  seen  the  prepara- 
tions it  affords,  but  judging  from  our  experience  with  drugs  and 
solvents  we  see  no  reason  why  the  process  should  not  afford  a 
good  extract ;  yet  we  are  not  prepared  to  admit  that  it  is  equally 
efficient  mth  percolation  properly  carried  out.  The  column  of 
powder,  in  a  properly  arranged  percolater,  wdiich  has  been  pre- 
viously moistened,  and  packed,  offers  all  its  soluble  matter  to 
each  stratum  of  the  descending  column  of  menstruum,  as  it  passes 
down  slowly  through  the  pervious  mass,  and  the  first  portions 
of  such  percolate  must  necessarily  be  saturated  solutions.  As 
these  heavily,  loaded  portions  pass  out,  the  percolation  proceeds 
more  readily,  because  less  impeded  by  soluble  matter,  and  if  the 
fineness  of  the  particles  has  been  properly  attended  to,  so  that  the 
process  regulates  itself  with  sufficient  slowness  to  give  time  for 
the  full  solvent  action  of  each  portion  of  the  menstruum  on  the 
entire  mass  of  the  powder,  there  seems  no  possibility  of  failure 
to  obtain  more  highly  concentrated  solutions  than  in  any  other 
way  except  by  evaporation.  Spencer  Thomas'  process  simu- 
lates this  action  by  moistening  the  powder  with  successive  small 
portions  of  menstruum,  with  intervening  subjection  to  great 
pressure,  .so  as  to  extend  the  solvent  action  of  each  fraction  to 
all  the  powder;  but  the  success  of  this  idea  is  met  by  a  practical 
difficulty  in  gaining  the  requisite  force,  and  in  fact  does  not 
approach  the  efficiency  of  percolation  in  experienced  hands. 
