Am iniy:imirm'}     Acetic  Acid  in  Extracting  Drugs.  307 
used  to  moisten  and  percolate  the  third  portion  of  500  grammes.  This 
third  portion,  being  the  limit  to  which  it  was  decided  to  carry  the 
repercolations,  had  all  the  fractions  of  percolate  grouped  together 
in  groups  of  five,  and  these  larger  fractions  were  reserved  for 
further  comparison  and  for  assay,  each  portion  having  been  carried 
to  practical  exhaustion  by  fresh  menstruum  to  follow  the  weak 
percolates. 
The  irregularities  in  progression  of  all  the  columns  of  the  table 
are  doubtless  due  to  irregularities  in  the  packing  of  the  moistened 
powders  and  to  changes  of  temperature. 
It  must  not  fail  to  be  noticed  that,  although  the  rate  of  exhaus- 
tion is  in  favor  of  the  acetic  acid,  it  is  less  favorable  than  would 
appear  from  a  casual  comparison  of  the  figures.  For  example,  the 
difference  in  weight  of  100  c.c.  of  the  menstrua  is  (91*09  from 
101-43)  11-06  grammes.  The  difference  between  the  first  pair  of 
figures  of  the  table  is  (9-39—6-28=)  3-11  grammes,  or  nearly  one- 
half  of  the  acetic  acid  difference,  and  therefore,  to  render  these  col- 
umns strictly  comparable,  a  considerable  addition  is  due  to  the  fig- 
ures of  the  acetic  acid  columns.  But  the  amount  of  such  addition 
is  so  difficult  to  estimate  that  it  must  be  left  indefinite. 
The  nearly  uniform  differences  of  the  first  fractions  of  acetic  acid 
percolate  from  the  first  and  second  portions,  and  from  the  first  three 
fractions  of  the  third  portion,  indicate  that  the  acetic  acid  men- 
struum is  practically  saturated  with  the  constituents  of  the  cinchona 
that  are  soluble  in  this  menstruum,  whilst  the  increase  in  the  differ- 
ences of  the  first  five  fractions  of  U.S.P.  percolate  of  the  third  por- 
tion show  that  this  menstruum  has  a  much  greater  solvent  capacity 
than  the  10  per  cent,  acetic  acid.  When  the  difficult  solubility^ 
even  of  the  acid  salts  of  the  cinchona  alkaloids  is  remembered  this 
saturation  is  not  difficult  to  comprehend.  But  when  these  supposed 
saturations  were  tried  they  were  found  capable  of  dissolving  consid- 
erable quantities  of  the  total  alkaloids  obtained  from  the  assays  of 
other  portions  of  cinchona. 
The  fourth  portion  or  final  pair  of  columns  is  given  for  the  pur- 
pose of  comparing  by  differences  the  rate  and  degree  of  exhaustion 
in  two  percolations  with  the  acetic  acid  menstruum,  managed  in  ex- 
actly the  same  way,  but  differing  simply  in  the  fineness  of  the  pow- 
der, the  apparent  result  being  that  the  exhaustion  was  more  rapid 
though  hardly  more  complete  in  the  fine  powder  as  far  as  the  dif- 
ferences go. 
