Si6 
The  Assay  of  Jalap. 
f  Am.  Jour.  Pharm. 
\  Nov.-ml.cr,  1911. 
lid  and  allow  to  cool  somewhat,  i^our  the  mixture  of  drug-  and 
extract  into  the  percolator,  leaving  the  flask  in  the  top  to  drain. 
When  the  alcoholic  filtrate  has  become  somewhat  concentrated, 
mix  the  drug  remaining  in  the  flask  with  lo  c.c.  of  95  per  cent, 
alcohol  and  pour  the  mixture  into  the  percolator,  draining  the 
flask  as  before.  Repeat  the  washing  of  the  flask  and  the  marc 
in  the  same  manner  until  a  portion  of  the  percolate  fails  to  show 
any  opalescence  on  largely  diluting  with  water.  Concentrate  the 
liquid  at  a  gentle  heat  to  a  volume  of  about  10  c.c,  remove  the 
dish  from  the  bath,  and  add  water,  a  few  drops  at  a  time,  to  the 
warm  extract,  stirring  with  a  glass  rod,  until  the  gum  deposited 
by  the  concentrated,  strongly  alcoholic  solution  is  redissolved  and 
a  clear,  or  nearly  clear,  fluid  is  obtained.  Continue  to  add  water 
in  small  portions,  stirring  thoroughly  after  each  addition,  up  to 
a  total  quantity  of  60  c.c,  when  the  resin  will  have  separated 
completely  and  may  be  collected  in  a  mass  under  the  aqueous 
solution,  which  should  be  quite  clear.  Put  the  dish  on  a  boiling 
water-bath  and  heat  with  frequent  stirring  until  the  volume  of 
liquid  is  reduced  about  one-third  and  the  odor  of  alcohol  has 
disappeared.  Remove  the  dish  from  the  bath,  stir  the  liquid  slowly 
so  that  the  resin  will  collect,  drawing  any  particles  floating  on  the 
surface  to  one  side,  and  decant  the  solution  through  a  small  filter. 
Cover  the  resin  with  25  cc  of  water,  return  the  dish  to  the  bath, 
and,  while  the  resin  is  hot  and  stringy,  mix  it  thoroughly  with 
the  water.  Remove  from  the  bath,  collect  the  resin  as  before,  and 
decant  the  water  through  the  filter.  In  like  manner  wash  the 
resin  a  second  time  with  25  c.c  of  water.  Wash  the  edge  of  the 
filter  with  a  little  warm  water  and  reject  the  several  aqueous 
filtrates,  first  noting  whether  they  are  clear  or,  at  most,  show  only 
that  faint  opalescence  peculiar  to  solutions  of  gums.  By  means 
of  a  fine  stream  of  hot  alcohol  from  a  wash-bottle,  rinse  the  water 
remaining  in  the  filter,  together  with  any  traces  of  resin,  into  the 
dish,  then-  wash  down  the  sides  of  the  latter,  finally  warming  and 
stirring  until  the  resin  is  redissolved.  Pour  the  alcoholic  solution 
through  the  filter  into  a. tared  Erlenmeyer  flask,  wash  the  dish 
and  filter  carefully  with  hot  alcohol,  evaporate  the  solvent,  and 
dry  the  resin  to  constant  weight  in  a  water-oven. 
Notes. —  (i)The  complete  extraction  of  the  cell-contents  of 
a  drug  depends  on  the  permeation  by  the  solvent  of  every  cell; 
