196 
ADDRESS. 
others  little,  if  any.  The  collectors  of  the  bark  are  liable  through 
ignorance,  or  tempted  by  gain,  to  substitute  one  for  the  other. 
How  shall  the  apothecary,  thousands  of  miles  away  from  the 
lofty  Cordilleras,  where  the  bark  is  gathered,  be  able  to  avoid 
the  results  of  this  ignorance,  or  fraud,  and  shield  the  sick  from 
the  effects  of  the  inert  substitution  ?  You,  Gentlemen,  can  reply 
to  this  question,  that  you  have  been  taught  the  nice  means  of 
discrimination,  by  which  the  genuine  are  distinguished  from  the 
spurious,  or  the  bark  of  one  species  from  that  of  another,  by  the 
color,  the  taste,  the  structure,  the  mosses  that  grow  on  their 
surfaces,  but,  beyond  all  other  means,  by  that  fnagical  power  of 
the  chemist,  which  compels  each  bark  to  give  up  its  secret 
strength,  in  kind  and  quantity,  to  his  scrutinizing  examination. 
Among  the  natural  causes  which  determine  the  value  of  medi- 
cinal substances,  climate  and  soil  exert  a  most  remarkable  in- 
fluence. Fox-glove,  so  valuable  as  an  arterial  sedative  in  Europe, 
is  shorn  of  half  its  power,  when  grown  in  the  United  States  ; 
Opium,  when  obtained  in  Turkey,  differs  materially,  both  in 
power  and  composition,  from  that  produced  in  the  valley  of  the 
Nile ;  and  these,  again,  from  the  varieties  raised  in  central  In- 
dia for  the  consumption  of  China.  In  the  recesses  of  Chinese 
Tartary,  carefully  excluded  from  observation  by  the  celestial 
policy,  grow  those  valuable  species  of  Rhubarb,  yielding  the 
best  varieties  of  the  drug,  which,  after  centuries  of  medical  ex- 
perience, continue  to  hold  a  prominent  position  among  the  in- 
dispensables  of  the  Materia  Medica.  Various  efforts  have  been 
made  to  introduce  these  plants  into  Europe,  and  with  apparent 
success  ;  but  though  they  grow  with  luxuriance,  the  principles 
upon  which  their  medicinal  value  depend  are  but  imperfectly 
developed ;  and  as  medicines,  they  are  unfit  to  replace  their 
oriental  progenitors.  Notwithstanding  this  fact  has  been 
proven  and  carefully  recorded,  thousands  of  pounds  of  European 
rhubarb  are  annually  thrown  into  commerce,  and  consumed, 
not  on  its  own  merits,  but  as  a  cheap  means  of  adulterating  the 
more  costly  varieties  of  the  East.  Some  of  this  European  root 
rivals  the  genuine  in  the  beauty  of  its  internal  structure  and 
coloring;  but  its  odor,  and  taste,  and  chemical  composition, 
cease  to  correspond.  From  some  local  peculiarity  of  soil,  oxalic 
acid  combined  with  lime,  is  largely  an  ingredient  in  Tartarian 
rhubarb,  whilst  this  salt  is  very  slightly  found  in  the  product  of 
