262  Extract  of  Jalap.  {Amj^S£m- 
EXTRACT  OF  JALAP. 
BY  G.   H.   CHARLES  KLIE. 
The  formula  of  the  UU.  S.  Pharmacopoeia"  for  the  preparation  of 
the  extract  of  jalap  is  : 
Take  of  Jalap,  in  moderately  fine  powder,  12  Troyounces, 
Alcohol,  4  pints, 
Water,  a  sufficient  quantity. 
Introduce  the  powder,  previously  mixed  with  3  fluidounces  of  alco- 
hol into  a  conical  percolator,  and  gradually  pour  upon  it  the  remainder 
of  the  alcohol.  When  the  liquid  ceases  to  pass,  pour  sufficient  water 
upon  the  residue  to  keep  its  surface  covered,  until  4  pints  of  tincture 
have  passed.  Set  this  portion  aside,  and  continue  the  percolation  until 
6  pints  of  infusion  have  been  obtained.  Distill  off  the  alcohol  from 
the  tincture,  and  evaporate  the  infusion  until  the  liquids  respectively 
have  been  brought  to  the  consistence  of  thin  honey  ;  then  mix  them, 
and  evaporate  them  to  the  proper  consistence. 
The  expression,  "introduce  into  a  percolator is  rather  indefinite.  It 
leaves  the  operator  to  guess  whether  to  use  light,  heavy  or  no  pressure 
at  all.  I  find,  that  in  the  first  part  of  the  process,  where  the  jalap  is 
exhausted  with  alcohol,  no  matter  how  firm  it  is  packed,  the  alcohol 
will  pass  freely,  and  without  difficulty.  The  trouble  commences  when 
the  water  is  poured  on.  According  to  how  the  powder  was  pressed 
in  the  percolator,  the  water  will  penetrate  ;  if  firmly,  very  slow  ;  and 
when  it  has  penetrated  two-thirds,  which  takes  about  ten  days,  it  is  so 
overcharged  with  extract  that  it  will  not  advance  perceptibly.  When 
the  powder  is  loosely  packed,  the  water  penetrates  somewhat  faster  ; 
but,  when  two-thirds  of  the  mass  is  penetrated,  the  same  difficulty 
occurs.  The  line  between  the  alcoholic  tincture  and  water  is  well 
defined — the  latter  in  its  descent  becoming  charged  with  extract,  as- 
sumes a  dark-brown,  almost  black  color.  If  the  apparatus  is  now  left 
to  itself,  it  may  stand  months,  and  still  percolation  will  not  be  finished. 
To  accelerate  the  process,  I  found  the  following  to  be  about  the  best 
method  :  I  poured  water  on  the  powder  until  it  stood  above  the  latter 
five  inches,  and  then,  at  intervals,  stirred  the  mass  down  to  the  line  of 
separation.  The  stirring  re-incorporates  the  thick,  viscid,  dark-colored 
line  of  separation,  and  gives  the  thinned  liquid  a  better  chance  to  pen- 
etrate. By  this  mode  the  alcoholic  tincture  was  driven  out  in  a  com- 
paratively short  time.    The  tincture  measured  3  pints  and  14  fluid- 
