AmMay)r*i8>78arm  }      Fluid  Extracts  by  Rep er eolation.  217 
the  percolator  for  an  automatic  supply  of  menstruum,  and  start  the  per- 
colation at  such  a  rate  as  to  give  1  part  of  percolate  in  about  4  hours. 
Reserve  the  first  6  parts  of  percolate  and  continue  the  percolation 
until  the  Cinchona  is  exhausted,  separating  the  percolate  received  after 
the  reserved  portion  into  fractions  of  about  8  parts  each. 
Moisten  a  second  portion  of  8  parts  of  the  Cinchona  with  8  parts 
of  the  weak  percolate, — the  first  portion  that  was  obtained  next  after 
the  reserved  percolate, — and  allow  the  moist  powder  to  stand  for  8  hours 
in  a  vessel  closely  covered.  Then  pack  it  moderately  in  a  percolator, 
and  supply  the  percolator  automatically  with  the  remaining  fractions  of 
the  weak  percolate  in  the  order  in  which  they  were  received,  and 
finally  with  fresh  menstruum  until  the  Cinchona  is  exhausted. 
Percolate  in  the  same  manner  and  at  the  same  rate  as  with  the  first 
portion  of  Cinchona,  and  reserving  8  parts  of  the  first  percolate, 
separate  the  weaker  percolate  into  fractions  of  about  8  parts  each. 
Percolate  the  third  and  fourth  portions  of  8  parts  each  of  the  Cin- 
chona in  the  same  way  as  the  second  portion. 
Finally  mix  the  four  reserved  percolates  together  to  make  30  parts  of 
finished  fluid  extract ;  and  having  corked,  labelled  and  numbered  the 
bottles  containing  the  fractions  of  weak  percolate,  set  them  away  until 
the  process  for  Cinchona  is  to  be  resumed 
When  this  fluid  extract  is  to  be  again  made,  repeat  the  process  as 
with  the  second  portion,  and  reserve  8  parts  of  the  first  percolate  as 
finished  fluid  extract  from  each  8  parts  of  Cinchona  from  that  time 
forward  so  long  as  the  fractions  of  weak  percolate  are  carried  forward 
with  which  to  commence  each  operation. 
In  applying  this  formula  and  process  each  part  was  taken  as  an 
avoirdupois  ounce,  and  therefore  each  percolation  was  made  with  a  half 
pound  avoirdupois  of  the  Cinchona  ;  and  the  menstruum  was  made  in  a 
tared  bottle  from  time  to  time  as  required. 
As  before  stated,  the  series  was  made  to  consist  of  6  percolations 
and  therefore  the  last  2  are  in  addition  to  the  4  of  the  formula,  as  if 
the  process  had  been  twice  resumed,  and  the  results  of  these  2  are 
entitled  to  most  attention  as  showing  the  true  practical  character  of 
the  process  of  repercolation.  And  every  percolation  which  might 
follow  these  can  be  demonstrated  mathematically  to  approach  nearer 
and  nearer  to  accurate  results  the  farther  the  series  is  extended,  since 
