THE 
AMERICAN  JOURNAL  OF  PHARMACY. 
MARCH,  1865. 
ON  A  NEW  PROCESS  FOR  MAKING  CONCENTRATED 
FLUID  EXTRACTS. 
By  N.  Spencer  Thomas. 
Mr.  Editor, — Having  been  several  years  engaged  in  making 
fluid  extracts  of  that  class  representing  pound  by  pound*  the 
crude  drug,  on  a  large  scale  for  the  trade,  and  always  on  the 
alert  for  the  best  process,  and  finding  extracts  prepared  in 
"vacuo"  much  approved — and  justly  so,  too,  as  compared  with 
any  other  process  then  known — I  adopted  that  plan  as  the  best 
•  for  evaporating,  and  found,  after  close  observation  of  its  working 
for  a  long  time,  that  it  was  perfection  for  making  solid  extracts ; 
but  even  with  it,  there  was  an  imperfection  in  the  preparation  of 
fluid  extracts.  This  imperfection  or  defect  seemed  at  first  to  be 
insurmountable,  as  the  difficulty  was  not  in  the  mode  of  evapo- 
ration, but  in  the  operation  itself.  Where  there  is  any  mixture 
of  menstrua  of  different  volatility,  as  alcohol  and  water,  the  diffi- 
culty that  presents  itself  is  simply  this :  the  first  part  of  the 
process  for  making  a  fluid  extract  is  making  an  alcoholic 
tincture  with  alcohol  more  or  less  strong,  according  to  the 
nature  of  the  drug-  The  next  step  is  to  evaporate  or  distil, 
and  as  we  can  thus  avoid  over  a  hundred  degrees  of  heat,  we 
introduce  the  tincture  into  the  vacuum-pan  and  proceed;  the 
alcohol  being  most  volatile,  evaporates  or  distils  off  first,  leaving 
the  desired  measure  of  fluid  extract  without  alcohol,  or  very 
little,  if  any — it  being  in  fact  an  aqueous  solution,  or  mixture 
of  an  aqueous  solution  with  various  precipitates  which  would 
require  alcohol  to  be  held  in  solution,  varying  according  to 
[*The  author  probably,  intends  "pound  to  pint,"  or  ounce  to  fluid- 
ounce.    Grain  to  minim  is  the  correct  expression. — Ed.  A.  J.  Ph.} 
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