ON  THE  PRESERVATION  OF  FLUID  EXTRACTS. 
121 
however,  it  may  be  different.  If  the  separated  resins  are  of  any 
medicinal  value,  we  must,  to  preserve  them,  dissolve  them  if  pos- 
sible. When  all  medicinal  virtue  resides  in  resinous  matter,  it 
may  be  most  practicable  to  have  them  dissolved  in  alcohol ;  but 
it  is  often  the  case  that  only  small  quantities  of  resin  are  pres- 
ent, which  nevertheless  will  not  be  kept  in  solution  by  the  sugar. 
To  retain  it  we  have  various  ways,  one  of  which  is  recognized 
by  our  national  Pharmacopoeia  in  the  case  of  fluid  extract  of  senna 
and  spigelia.  I  refer  to  the  employment  of  an  alkali  or  its  car- 
bonate, to  effect  the  solution,  which  has  also  been  proposed  by 
Professor  Procter  for  fluid  extract  of  jalap,  and  may  be  service- 
able in  other  instances. 
Another  way  is  the  partial  employment  of  alcohol  as  a  solvent, 
as  a  precedent  to  which  I  refer  to  E.  Parrish's  suggestion  for 
fluid  extract  of  cinchona  (Parrish's  Practical  Pharmacy,  p.  171.) 
If  the  sugar  is  dissolved  by  a  very  moderate  heat,  and  the  evapo- 
ration to  the  proper  measure  conducted  at  the  same  temperature, 
a  sufficient  quantity  of  alcohol  will  remain  behind  to  keep  the 
cincho-tannic  salts  in  solution.  The  fluid  extract  thus  made  is 
syrupy,  perfectly  transparent,  of  a  deep  Malaga  wine  color,  and, 
in  the  course  of  18  months,  being  kept  in  a  partially  filled  bottle 
frequently  opened,  has  not  precipitated  one-fourth  the  quantity 
of  coloring  and  other  matter,  as  an  equal  volume  of  the  tincture 
of  cinchona,  made  with  the  same  calisaya  bark,  and  being  only 
three-eighths  the  strength  of  the  fluid  extract.  I  believe  this  to 
be  a  speaking  example  in  favor  of  the  employment  of  sugar. 
As,  however,  by  manipulating  differently  or  at  a  different  degree 
of  heat,  the  amount  of  alcohol  must  necessarily  vary,  ib  ^night 
perhaps  be  preferable  to  have  a  certain  quantity  added  to  the 
completed  extract,  say  about  2  oz.  for  the  pint.  Since  then  I 
have  prepared  various  extracts  in  a  similar  manner,  such  as  fluid 
extract  of  cimicifuga,  serpentaria,  buchu,  &c;  in  the  latter  in- 
stance, however,  I  have  been  unable  to  separate  entirely  the 
chlorophyll ;  the  quality  of  such  extracts  I  believe  to  be  unex- 
ceptionable. 
Another  consideration,  not  to  be  disregarded  in  making  fluid 
extracts,  is  their  taste,  and  to  make  this  as  agreeable  as  possible, 
is  a  duty  which  we  owe  to  the  sick.  This  end  is  gained  by 
sugar,  which  more  readily  masks  a  bitter  and  disagreeable  taste 
