ON  THE  PRESERVATION  OF  FLUID  EXTRACTS. 
221 
Before  concluding,  allow  me  to  remark  that  the  value  of  ex- 
periments in  chemiatry  or  pharmacy  is  not  affected  by  the  local- 
ity which  originates  them.  An  eastern,  western,  northern  or 
southern  location  does  not  add  to  or  detract  from  one  jot  or  one 
tittle  of  their  value.  The  skill  with  which  they  are  conducted 
and  the  truths  which  they  develope  are  all  that  is  to  be  consider- 
ed. Experiments  to  prove  theoretical  reasoning  are  seldom  so 
valuable  as  experience  gained  in  conquering  difficulties  occurring 
in  practice.* 
Cambridge,  Mass,  March  31,  1859. 
*  Note.  Since  reading  Mr.  Thayer's  paper,  we  have  carefully  reperused 
that  of  Mr.  Maisch,  to  which  it  refers,  and  do  not  think  that  the  latter  had 
in  view  any  particular  writer  or  manufacturer,  but  addressed  himself  to 
the  subject  itself,  in  doing  which  he  necessarily  had  to  allude  to  those  who 
had  written  upon  it.  It  struck  us  that  Mr.  Maisch's  paper  was  unusually 
free  from  prejudice.  What  it  needed  was  an  acquaintance  with  the  actual 
changes  that  occur  in  concentrated  tinctures,  or  fluid  extracts,  such  as  Mr. 
Thayer  prepares,  and  which  lie  had  not  an  opportunity  to  gain.  The  best 
place  to  derive  this  knowledge  would  be  at  an  agency  of  the  manufacturer, 
where  a  stock  of  all  kinds  is  kept,  and  there  inspect  the  unopened  bottles 
as  they  are  offered  to  the  trade,  A  hasty  examination  of  a  variety  of  al- 
coholic fluid  extracts,  at  an  agency  in  this  city,  resulted  in  finding  at  least 
two-thirds  of  them  with  sediment,  in  variable  quantity.  We  confess  that 
after  reading  all  that  has  been  written,  that  we  incline  to  the  opinion  that 
the  preservative  agent  will  have  to  vary  in  kind  and  properties  to  suit  the 
circumstances  of  the  case,  and  that  an  attempt  to  use  only  alcohol  or  only 
sugar  will  result  in  disappointment,  either  pharmaceutically  or  therapeuti- 
cally. 
In  considering  the  changes  which  these  preparations  undergo  by  age  and 
exposure,  it  is  necessary  to  study  the  composition  of  the  soluble  matter 
of  each  drug,  and  the  tendency  to  a  disturbance  of  solubility  by  the  mu- 
tual reaction  of  the  contained  principles.  Let  us  instance  what  we  mean 
in  a  familiar  example.  It  is  now  pretty  generally  conceded  that  the  resins 
and  crysophanic  acid  in  rhubarb  are  largely  concerned  in  the  cathartic 
power  of  that  drug,  although  its  collective  medicinal  power  includes  other 
principles.  If  we  make  a  watery  infusion  of- rhubarb,  it  will  be  found  that 
these  principles,  almost  insoluble  in  water  in  an  isolated  state,  are  found 
in  solution,  through  the  aid  of  associated  substances,  just  as  insoluble 
cantharidin  is  naturally  soluble  in  water,  as  it  exists  in  the  fly.  If  we  treat 
coarsely  powdered  rhubarb  by  direct  percolation  with  alcohol  of  70  per 
cent.,  we  easily  get  a  concentrated  solution  of  all  that  is  soluble  in  the 
drug,  desirable  to  be  extracted.    If  now,  we  concentrate  this  carefully  by 
