326    GLYCERIN  TO  PREVENT  THE  DEPOSITION  OF  APOTHEME. 
Fluid  Extract  of  Cinchona. — This  extract,  prepared  according 
to  the  formula  given  in  my  essay  on  the  subject  last  year,  ap- 
pears to  be  in  every  respect  satisfactory.  I  would  not  recom- 
mend any  reduction  in  the  quantity  of  Glycerin  there  ordered, 
although  a  trifling  reduction  might,  perhaps,  be  made  without 
injury  to  the  preparation.  Upon  being  diluted  with  water  it  is 
rendered  turbid,  but  the  infusion  thus  made  extemporaneously 
becomes  clear  again,  upon  the  addition  of  a  small  quantity  of 
diluted  sulphuric  acid,  or  of  elixir  vitriol. 
Fluid  Extract  of  Catechu. 
Fluid  Extract  of  Kino. 
Fluid  Extract  of  Krameria. 
The  formulas  given  for  these  preparations,  by  Prof.  Procter, 
in  his  paper  on  Fluid  Extracts,  published  in  the  volume  of  Pro- 
ceedings for  1863,  are  satisfactory,  and  the  quantity  of  Glycerin 
as  small  as  would  be  advisable. 
The  first  two  are  miscible  with  water  in  any  proportion  with- 
out precipitation  ;  the  Fluid  Extract  of  Krameria  is  slightly  pre- 
cipitated on  the  addition  of  water. 
Fluid  Extract  of  Rhubarb. — Not  being  entirely  satisfied  with 
this  preparation,  when  made  according  to  the  U.  S.  Pharmaco- 
poeia, I  was  induced  to  prepare  some  after  the  following  formula, 
in  accordance  with  a  suggestion  offered  in  my  essay,  read  last 
year. 
Take  of  Rhubarb  in  moderately  fine  powder  16  troy-ounces. 
Glycerin  8  fluidounces. 
Alcohol  24  fluidounces. 
Diluted  alcohol  a  sufficient  quantity. 
Moisten  the  Rhubarb  with  four  fluidounces  of  the  alcohol,  in- 
troduce it  into  a  conical  glass  percolator,  press  it  gently,  and 
pour  upon  it  gradually  twelve  fluidounces  of  alcohol.   When  the 
liquid  has  disappeared  from  the  surface,  gradually  pour  on,  first 
a  mixture  of  eight  fluidounces  each  of  Glycerin  and  Alcohol,  and 
afterwards  diluted  Alcohol,  until  three  pints  of  liquid  have  been 
obtained.    Set  aside  the  first  pint  obtained,  in  a  warm  place, 
until  reduced  by  spontaneous  evaporation  to  six  fluidounces. 
Evaporate  the  remainder  of  the  liquid  by  a  gentle  heat  to  ten 
