ON  THE  PROXIMATE  ANALYSIS  OF  PLANTS  AND  VEGETABLE 
SUBSTANCES. 
By  Frederick  Rochleder,  M.  D. 
INTRODUCTION. 
The  medicinal  action  which  many  plants,  or  parts  of  plants,  possess, 
may  have  been  principally  the  earliest  occasion  of  the  examination  of 
plants.  It  is  probable  that  the  analysis  of  plants,  and  particularly  of  their 
sap,  was  the  first  original  labor  in  relation  to  analytical  chemistry,  when 
the  term  analysis  could  be  scarcely  employed  in  the  sense  which  we  at- 
tach to  this  word  at  the  present  time.  Indeed,  some  derive  the  word 
"  Chemistry^^  from  x^y-'^^  (the  sap),  because  the  sap  of  plants  had  been  the 
object  of  the  earliest  chemical  research.  The  applicability  of  many  plants 
to  technical  purposes  was  the  later  and  profitable  occasion  for  the  analy- 
sis of  plants  and  their  parts.  It  is,  therefore,  evident  why  the  earliest 
labors  were  not  directed  to  discover  all  the  constituents  of  a  plant  or  of  its 
parts,  but  had  for  their  object  the  isolation  of  one  or  the  other  of  its  con- 
stituents. Chemists  endeavored  to  isolate  the  medicinally  active  sub- 
stance, or  the  poison  of  medicinal  or  poisonous  plants,  and  the  substances, 
as  coloring  matters,  tannin,  &c.,  of  plants,  used  for  industrial  purposes,  and 
on  these  accounts  employed.  Nevertheless,  we  very  seldom  find  analyses 
of  all  parts  of  a  plant ;  mostly,  analyses  were  preferred  of  those  parts  of 
plants  which  were  employed  in  medicine  or  in  the  arts.  All  analyses 
were  undertaken  from  views  which  must  remain  foreign  to  chemistry  as 
a  science,  which  proceeds  without  regard  to  medical  or  technical  objects. 
Another  period  commenced  first  in  more  recent  times  in  the  investigation 
of  plants,  in  which  the  former  predominating  views  were  more  and  more 
thrown  into  the  background  ;  chemists  became  sensible  that  one  constitu- 
ent of  a  plant  possessed  for  the  plant  the  same  degree  of  importance  as 
any  other,  quite  independently  of  its  applicability  to  different  objects. 
They  perceived  that  all  the  constituents  of  a  plant  must  stand  in  the  closest 
relations  to  one  another  ;  that  one  is  formed  from  the  other,  that  the  exist- 
ence of  one  constituent  could  not  be  regarded  independently  of  the  exist- 
ence of  the  others,  and  that  all  constituents  are  links  of  one  chain.  The 
principal  result  of  these  nevr  views  was  an  alteration  in  the  method  of 
investigating  plants  ;  it  could  no  longer  be  said  to  be  a  one-sided  endea- 
vor for  the  isolation  of  a  substance  with  a  disregard  to  all  other  simultane- 
ously existing  constituents.  It  became  necessary  to  search  for  all  the  con- 
stituents of  a  vegetable  substance  by  analysis,  and  to  study  them  closely. 
The  inquiries  concerning  the  process  by  which  one  constituent  is  formed 
from  others,  and,  according  to  the  nature  of  the  affinities,  is  converted 
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