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ON  FLUID  EXTRACT  OF   RHUBARB  AND  SENNA. 
(U.  S.  P.),  allowtbem  to  macerate  twenty-four  hours,  and  introduce 
the  mixture  into  a  percolator  furnished  below  with  a  stop-cock  or 
cork  to  regulate  the  flow.  A  mixture  of  one  part  of  alcohol  and 
three  of  water  should  now  be  poured  on  above,  so  as  to  keep  a 
constant  but  slow  displacement  of  the  absorbed  menstruum,  until 
one  gallon  of  tincture  has  passed.  Evaporate  this  in  a  water  bath 
to  eleven  fluid  ounces,  dissolve  in  it  the  sugar  and  bicarbonate,  and 
after  straining,  add  the  tincture  of  ginger,  holding  the  oils  in  solu- 
tion and  mix.    When  done  the  whole  should  measure  a  pint. 
Remarks.  If  the  percolation  has  been  properly  conducted,  the 
ingredients  will  have  been  sufficiently  exhausted  when  six  pints  of 
fluid  have  passed.  As  by  far  the  larger  portion  of  the  soluble  matter 
passes  in  the  first  two  pints,  it  is  well  to  set  these  aside  and  evap- 
orate them  separately  to  six  fluid  ounces,  subsequently  adding  it 
to  the  other  liquid  when  it  has  been  reduced  to  five  fluid  ounces. 
As  the  cathartic  principles  of  senna  and  rhubarb  are  very  suscep- 
tible to  injury  from  heat,  especially  in  contact  with  the  air,  the 
propriety  of  using  the  best  available  means  for  conducting  the 
evaporation  need  not  be  urged.  When  the  evaporation  is  con- 
ducted in  open  vessels,  some  advantage  is  gained  by  adding  the 
sugar  to  the  tincture  and  continuing  the  porcess  until  it  mea- 
sures fifteen  fluid  ounces.  The  sugar  protects  the  extractive 
matter  from  oxidation  and  more  completely  suspends  or  dissolves 
the  resinous  part  of  the  rhubarb  contained  in  the  tincture.  The 
bicarbonate  should  not  be  added  to  the  extract  while  it  is  above 
140°  Fahr.  and  should  be  reduced  to  powder  previously. 
It  may  be  objected  to  this  formula  that  we  already  have  fluid 
extracts  of  rhubarb  and  of  senna  of  the  same  ratio  of  strength,  and 
that  when  physicians  need  such  an  association,  they  can  mix  them. 
In  answer,  it  may  be  stated  that  the  cases  where  a  simple  cathar- 
tic is  needed,  are  so  numerous  that  this  preparation  will  be  found 
useful  to  the  physician,  and  a  good  medicine  for  travellers  and  others 
who  resort  to  this  kind  of  purgative  habitually. 
