118  ON  CAMPBELL'S  PROCESS  FOR  MAKING  FLUID  EXTRACTS. 
fourth,  the  whole  thoroughly  incorporated  and  transferred  to  a 
conical  percolator,  covered  with  a  disk  of  filtering  paper,  upon 
which  the  remaining  f^l2  of  menstruum  were  poured.  When 
the  percolate  had  penetrated  the  sponge,  placed  in  the  neck,  a 
cork  was  inserted,  and  the  whole  was  allowed  to  stand  four  days  ; 
after  which,  the  cork  being  removed,  the  percolate  was  allowed 
to  drop  into  a  receiving  vessel.  Finding  that  all  the  menstruum 
had  been  absorbed,  f^  16  of  alcohol  were  added,  and  f^  15  of 
extract  were  obtained  as  the  result.  Pouring  on  another  f^, 
the  preparation  was  brought  up  to  its  requisite  volume.  The 
fgl6  thus  obtained  were  set  aside,  and  percolation  continued 
with  alcohol,  until  f^l6  of  exhausted  liquor  had  passed,  which 
were  allowed  to  evaporate  spontaneously.  The  residue  consisted 
of  resin  and  glycerin,  the  amount  of  resin  present  being  80 
grains,  or  one  and  one-twenty-fourth  p.  ct.  of  the  weight  of  the 
drug  employed. 
2d.  Wild  cherry  bark,  of  requisite  fineness,  was  carefully  per- 
colated with  a  menstruum,  consisting  of  equal  parts  of  glycerin 
and  water.  The  result  was  an  intensely  dark  extract,  possess- 
ing the  characteristics  and  odor  of  the  bark  in  a  marked  degree. 
After  obtaining  the  fluid  extract,  percolation  was  resumed  with 
water,  to  find  the  amount  of  undissolved  extractive  matter, 
which  was  six  p.  ct.  The  exhaust  obtained  by  continued  per- 
colation with  water  was  highly  colored  and  possessed  a  marked 
odor  of  the  drug,  showing  evidently  that  the  bark  was  not  fully 
exhausted.  The  process  for  the  manufacture  of  this  fluid  ex- 
tract is  extremely  simple,  the  only  doubt  arising  in  my  mind  is 
whether  the  glycerin  is  capable  of  arresting  fermentation,  to 
which  aqueous  preparations  of  this  drug  are  so  liable. 
3d.  16  troyounces  of  select  rhubarb  were  reduced  to  a  suf- 
ficiently fine  powder  to  pass  through  a  No.  40  sieve,  moistened 
with  fj6  of  a  menstruum  composed  of  glycerin  one-fourth,  water 
one-fourth  and  alcohol  one-half,  and  treated  in  the  same  way  as 
in  the  fluid  extract  of  ginger.  It  required  24  additional  fluid- 
ounces  of  dilute  alcohol  to  displace  f^l6  of  the  extract,  which 
were  set  aside,  and  percolation  resumed  with  dilute  alcohol  until 
the  drug  was  thoroughly  exhausted.  The  alcohol  was  recovered 
by  distillation,  the  residue  transferred  to  a  water  bath  and  al- 
