ECONOMY  IN  THE  USE  OP  ALCOHOL  IN  PERCOLATION. 
3 
and  that  heating  so  changed  the  physical  properties  of  the  resin 
as  to  prevent  its  being  recognized  by  any  known  description. 
The  fourth  series  proved  that  the  use  of  too  much  acid  in  the 
precipitation  rendered  the  product  granular,  heavy  and  moist, 
dark  in  color,  and  diminished  in  quantity. 
The  fifth  series  proved  the  useful  practical  limits  of  acidulating 
the  water  for  precipitation  to  be  not  less  than  ten  minims,  nor 
more  than  forty  minims  to  each  pint  of  water.  That  three  pints 
of  acidulated  water  was  sufficient  for  each  7680  grains  of  powder ; 
and  that  the  product  cannot  be  dried  at  a  temperature  much 
above  90°  F.  without  risk  of  becoming  hard  and  discolored,  but 
that  below  that  temperature  it  uniformly  retains  its  light  friable 
condition  and  its  light  color. 
The  sixth  series  determined  the  progress  and  rate  of  exhaustion 
in  percolating  a  very  fine  powder.  The  fact  that  the  resin  was 
the  only  purgative  portion  of  the  root  was  proved  by  repeatedly 
swallowing  boluses  of  the  extract  deprived  of  the  resin  only,  in 
quantities  increased  up  to  60  grains  at  a  dose.  And  the  circum- 
stance that  such  doses  were  continued  through  two  days  without 
discoverable  effect  of  any  kind,  leads  to  the  inference  that  this 
extract  is  inert,  like  the  similar  extract  of  jalap.  Then,  as  the 
resin  is  easily  and  perfectly  precipitable,  the  powder  offered  an 
excellent  type  for  determining  in  a  very  practical  and  useful 
way  the  effect  of  percolation  in  exhausting  the  powder  of  its 
resin,  and  of  its  extractive  matter,  and  of  comparing  the  progress 
of  the  exhaustion  in  relation  to  these  two  constituents  of  the 
product.  Both  the  resin  and  the  extractive  matter  are' very 
soluble  in  the  menstruum,  and  apparently  equally  so;  and  as  the 
association  of  the  two  in  the  root  must  be  very  close,  it  might  be 
expected  that  the  alcohol  would  extract  the  two  together  in  their 
natural  association, — that  is,  that  every  particle  of  extract,  from 
first  to  last,  would  contain  its  corresponding  proportion  of  the 
resin.  This,  however,  is  not  the  case,  the  resin  being  extracted 
far  more  rapidly  than  the  inert  extractive  matter ;  and  this  re- 
markable circumstance  is  of  great  interest  and  importance  in  its 
bearing  upon  percolation  in  general,  and  particularly  where  alka- 
loids are  to  be  extracted.  In  the  experiments  recently  published, 
wherein  the  cinchona  alkaloids  were  determined  in  the  successive 
