H  2  2  Fluid  Extracts  by  Rep er eolation.      { ^'dly^lyt™' 
about  8  ounces  =226-8  grams,  each.  These  portions,  by  the  same 
calculations,  yielded  respectively  59*85,  37*26,  22*16,  7*15  and  277 
grams,  =129/ 19  grams,  of  extract.  Of  this  102*45  grams,  was  carried 
forward  to  it  in  weak  percolates  from  the  sixth  percolation  of  the  table. 
The  8  ounces  =226*8  grams,  reserved  contained  59*85  grams,  of 
extract,  leaving  4  portions  of  weak  percolate  to  be  carried  forward  con- 
taining (129*19 — 59*85  =)  69*34  grams,  of  extract.  But  the  extract 
which  appears  to  have  been  obtained  by  this  percolation  is  only  (129*19 
— 102*45=)  26*74  grams  and  yet.  the  powder  was  about  as  well 
exhausted  as  any  of  the  previous  percolations,  and  the  weak  percolates 
carried  forward  were  much  less  loaded  with  extractive. 
This  improvement  of  the  process  by  the  use  of  a  less  exceptional 
quality  of  Cinchona  was  however  still  evidently  insufficient,  and  left  it 
still  short  of  the  best  results.  The  menstruum  was  next  to  be  changed, 
as  it  plainly  needed  more  alcohol  to  exclude  some  of  the  extract,  and 
probably  less  glycerin. 
A  new  menstruum  was  made  consistiug  of  5  parts  stronger  alcohol, 
4  parts  water  and  1  part  glycerin.  The  s.  g.  of  this  mixture  was  "9575 
at  15-6°  C.=6o°  F.,  or  '9496  at  250  C.  =  77°  F.  A  cubic  centi- 
metre of  this  menstruum  carefully  weighed  and  evaporated  on  a  watch- 
glass  left  7*75  per  cent,  of  glycerin  not  evaporable  at  the  temperature 
to  which  the  fractions  of  percolate  were  submitted.  A  new  series  of 
percolations  was  started  with  this  menstruum,  and  was  conducted 
preciselv  as  with  the  former  series.  The  first  two  percolations  were 
made  with  the  rich  Java  Cinchona  so  as  to  compare  the  results  of  the 
two  menstrua  upon  the  same  powder  ;  and  then  a  third  percolation  was 
made  with  the  Ceylon  powder  for  comparison  with  the  other  men- 
struum upon  this  powder  as  above  given  in  the  seventh  percolation  of 
the  former  series.  There  was  not  time  to  extend  this  series  beyond  the 
third  percolation,  but  fortunately  the  indications  from  the  three  are 
pretty  clear.  In  this  series  the  percolate  was  divided  into  portions  of 
8  ounces  =226*8  grams,  each  except  the  first  portion  of  the  first  perco- 
lation, which  was  6  ounces  =170*1  grams,  and  the  powder  in  each 
was  moistened  with  8  ounces  =226*7  grams,  of  menstruum  or  weak 
percolate.  So  moistened  it  could  not  have  been  passed  through  the  sieve 
at  once,  but  by  standing  for  the  prescribed  8  hours  in  a  closely-covered 
vessel  the  liquid  was  absorbed  by  the  powder,  and  then  it  was  easily  passed 
through  the  sieve.  When  moistened  to  this  extent  the  powder  must  not 
