ON  THE  PRESERVATION  OF  FLUID  EXTRACTS. 
217 
If  the  writer  confounds  me  with  those  who  strive  to  prove 
that  strong  alcohol  is  the  great  and  only  extracting  and  pre- 
serving menstruum,  lean  only  say  that  he  i  smistaken  ;  that  I 
have  rather  preferred  to  avail  myself  of  established  scientific 
principles,  to  building  up  new  and  doubtful  theories.  In  my  pa- 
per I  said  nothing  concerning  the  practical  application  of  my 
ideas,  merely  considering  the  abstract  value  of  two  substances 
as  preservative  agents.  In  an  article  written  and  published  last 
year,  I  recommended  the  use  of  both  sugar  and  alcohol  in  fluid 
extracts,  remarking  that  sugar  "  assists  the  solution  of  the  pre- 
cipitates and  disguises  the  disagreeable  taste  of  many  extracts." 
I  advocated  the  use  of  alcohol,  because  I  believed  with  the 
writer  of  the  article,  that  it  effectually  counteracts  fermentation 
and  mould,  and  because  I  did  not  believe  with  him  that  in  fluid 
extracts  it  is  liable  to  acetous  fermentation.  Let  it  be  under- 
stood, that  in  speaking  of  sugar  as  not  a  safe  preservative,  I  re- 
fer to  purely  saccharine  extracts.  If  the  partial  employment  of 
alcohol  is  allowed,  there  can  be  with  me  no  controversy. 
The  article  starts  with  a  proposition  which  is  fatal  to  the  uso 
of  sugar  as  a  preservative.  In  substance  it  is  this ;  that  if  the 
alcoholic  principles  of  a  plant  are  insoluble  in  water  or  a  solu- 
tion of  sugar,  the  latter  as  a  menstruum  is  inadmissible. 
Sugar  aids  the  solvent  power  of  water,  but  this  aid  is  not  af- 
forded in  sufficient  degree  to  dissolve  the  alcoholic  principles 
which  exist  or  should  exist  in  concentrated  fluid  extracts.  It 
is  enough  to  point  to  the  cincho-tannates  from  calisaya  bark,  to 
the  resins  of  mandrake,  cannabis  indica,  jalap,  to  the  principles 
which,  although  evaporated  in  vacuo,  we  find  abundantly  deposi- 
ted from  henbane,  foxglove  and  other  narcotic  plants,  to  lupulin 
from  hops,  and  to  the  many  principles,  not  understood,  which 
alcohol  extracts  from  all  or  nearly  all  other  plants.  These  pre- 
cipitates are  not  due  to  the  absorption  of  oxygen  ;  they  are  not 
apotheme.  They  deposit  the  same  when  evaporation  is  conduct- 
ed in  a  vacuum.  They  are  medicinal  principles,  deposited  be- 
cause the  menstruum  loses  its  power  of  solution  in  consequence 
of  the  evaporation  of  alcohol.  I  believe  that  the  instances  are 
very  rare,  where  the  alcoholic  or  hydro-alcoholic  principles  of 
any  root,  bark  or  leaf  will  dissolve  in  a  solution  of  sugar,  in  the 
proportion  of  one  pound  of  raw  material  to  the  pint  of  liquid, 
