82 
eoc'hledsr's  proximate  analysis. 
into  other  substances,  liave  rendered  requisite  more  correct  analyses  with 
reference  to  all  ihe  constituents. 
The  first  efforts  of  chemists  in  the  analysis  of  plants  and  their  parts  were 
limited  to  the  separation  of  their  constituents  from  one  another,  as  far  as 
it  was  possible,  by  their  different  behaviour  to  solvents.  The  substances 
thus  separated,  often  still  a  mixture  of  several  bodies,  had  a  peculiar 
name  conferred  on  them,  but  their  composition,  their  relation  to  other 
bodies,  with  the  exception  of  some  observations  concerning  their  color,  or 
the  precipitates  produced  by  the  addition  of  reagents,  were  not  further  in- 
vestigated. From  a  resemblance  in  the  properties  of  individual  constitu- 
ents with  bodies  already  known,  their  identity  with  the  same  was  decided 
upon.  While  some  chemists  rather  predicted  than  were  able  to  detect  an 
unlimited  quantity  of  different  bodies  in  various  plants  by  a  great  number 
of  analyses  in  the  highest  degree  imperfect,  others  proceeded  to  examine 
more  closely  the  detected  constituents  individually.  It  was  quite  in 
the  nature  of  things  to  be  expected  that  for  the  investigation  of  the 
composition  and  constitution  of  their  individual  constituents,  those 
bodies  in  particular  should  be  selected  which  from  their  properties  ap- 
peared to  give  a  guarantee  of  their  purity  by  reason  of  the  facility  with 
which  they  coold  be  isolated  and  purified.  For  example :  volatile  oils,  by 
the  facility  with  which  they  are  volatilized  undecomposed,  and  are  sep- 
arated at  certain  boiling  points  from  other  volatile  substances  with  some 
precision  ;  also  crystallizable  bodies  of  some  permanence  which  may  be 
easily  separated  from  other  amorphous  substances  by  their  disposition  to 
assume  the  crystalline  form.  These  were  the  objects  of  attention  to  those 
men  of  science  who  expected  more  benefit  to  chemistry  from  a  fundamen- 
tal study  of  some  substances  than  by  the  discovery  of  many.  Thus,  then, 
it  happens  that  besides  some  few  well-conducted  analyses  of  vegetable  sob- 
stances,  we  possess  a  great  mass  of  imperfect  analyses,  and  sometimes  an 
exact  chemical  investigation  of  one  or  the  other  constituent  of  a  vegetable 
substance,  in  which  the  remainiug  constituents  Lave  received  no  considera- 
tion. There  exists,  at  the  present  day,  no  investigation  of  the  various 
parts  of  a  plant  which  has  been  completed  so  that,  uniting  the  details  of 
each  investigation  of  all  the  constituents  to  a  whole,  it  could  give  us  a  rep- 
resentation of  the  constitution  of  the  plant. 
The  investigation  of  an  individual  constituent  of  a  vegetable  often  re- 
quires a  long  time,  and  a  great  expenditure  of  patience  and  sagaci- 
ty, not  to  speak  of  the  pecuniary  sacrifice  combined  with  it.  For 
these  reasons  few  of  the  substances  have  been  at  present  examined  in  com- 
parison  with  the  riurioler  whose  existence  is  already  known.  But  an  exact 
and  complete  analysis  is  endlessly  troublesome  when  the  nature  of  the 
constituents  are  not  known.  To  this  is  to  be  ascribed  the  few  analyses  we 
possess  which  correspond  to  the  acquirements  of  science.  For  an  analysis 
which  informs  us  what  constituents  a  plant  contains  in  its  various  parts, 
