46  ON  THE  SOLUBILITY  OF  MEDICINAL  PRINCIPLES. 
application  of  this  law  only  to  those  proximate  principles  of 
organic  matter  which  are  properly  the  products  of  vegetable 
and  animal  life.  Among  the  multifarious  combinations  of  the 
primary  elements  which  are  the  results  of  the  destructive  de- 
composition of  vegetable  and  animal  matter,  there  may  be  found 
exceptions  to  this  rule  ;  some  preparations  may  be  found  which 
are  medicinal  or  poisonous,  and  yet  not  soluble  in  alcohol ;  but 
that  is  foreign  to  our  present  enquiry. 
To  prove  this  hypothesis  affirmatively  would  require  the  enu- 
meration of  every  article  of  the  vegetable  Materia  Medica,  with 
testimony  to  the  solubility  of  its  medicinal  principle  in  alcohol ; 
we  can  therefore  only  offer  the  negative  proof  of  challenging 
the  production  of  facts  that  militate  against  it.  These  we  be- 
lieve, if  any,  will  be  found  so  few  that  the  exceptions  will  but 
establish  the  rule. 
The  importance  and  application  of  this  law  will  be  readily  ap- 
preciated. The  particular  modes  of  manipulation  must  be  left 
to  the  judgment  of  the  pharmaceutist,  and  must  be  greatly  va- 
ried, according  to  the  nature  of  the  substance  operated  on. 
The  general  rule  of  operation  will  be  this  :  In  the  first  place, 
extract  from  the  crude  material  all  its  soluble  elements,  or  at 
least  be  sure  that  we  have  reached  and  eliminated  all  those  medi- 
cinal principles  which  we  seek.  For  this  purpose  we  may  em- 
ploy water,  alcohol,  ether,  or  other  agents,  or  these  combined 
or  in  succession,  as  experience  and  pharmaceutical  knowledge 
may  indicate.  Then,  from  this  primary  tincture  or  solution, 
draw  off,  by  the  still  or  the  vacuum  pan,  the  menstruum  used, 
and  reduce  the  extract  to  a  semi-fluid  or  syrupy  consistence, 
leaving  as  little  fluid  as  practicable  to  dilute  the  alcohol  to  be  used, 
and  yet  retain  sufficient  fluidity  to  allow  all  the  particles  to 
come  fully  in  contact  with  this  solvent.  Next  weaken  this  semi- 
fluid extract  with  absolute  alcohol,  or,  at  least,  with  that  of  such 
strength  as  will  not  dissolve  the  nutritive  and  inert  principles. 
In  doing  this,  use,  in  the  first  place,  about  two-thirds  or  three- 
fourths  the  quantity  for  the  proposed  volume  of  the  finished 
tincture,  and  after  sufficient  agitation  and  digestion  in  this,  de- 
cant or  filter  off  the  clear  liquid  and  set  it  aside.  Treat  the  re- 
maining precipitate  with  repeated  portions  of  alcohol  till  no- 
thing more  is  dissolved,  and  distil  off  the  spirit  from  these 
