2 io  Dr.  white’s  Experiments 
What  is  here  faid  is  underftood  of  plants  gathered 
and  feparated  from  the  roots.  Dr.  priestley  dilcovered 
a different  property  in  them  when  in  a vigorous,  grow- 
ing ftate,  they  then  abforb  from  the  atmofphere;  but 
this  ceafes  with  their  life,  they  then  exhale  putridity, 
and  haften  to  diffolution. 
We  come  next  to  another,  not  lefs  curious  and  impor- 
tant, part  of  our  experiments;  the  effects  of  the  effluvia 
from  moift,  marfhy,  and  other  kinds  of  foils,  upon  air. 
This  fubjeft,  as  particularly  connected  with  our  art, 
regarding  the  endemic  difeafes  of  different  countries, 
and  a -plentiful  fource  of  the  raoft  dangerous  difeafes, 
has  much  employed  the  attention  of  phyfidans  and  phi- 
’•lofophers.  The  nature  of  miafmata  is,  as  far  as  I know, 
as  yet  but  imperfedtly  underftood;  hence  general  una- 
nimity of  opinion  is  not  to  be  expefted : nor  can  a per- 
fect coincidence  in  the  refult  of  experiments  be  at  once 
attained,  efpecially  if  made  by  perfons  with  different 
views,  and  under  the  influence  of  different  ideas  and 
perhaps  prejudices. 
In  order  to  attain  truth,  we  muft  take  faithful  experi- 
ments, made  with  fedulous  obfervation,  for  our  guides;  we 
fhall  find  them  to  refledf  mutual  light  and  truth  upon  each 
other.  Thus  we  gradually  lift  up  the  veil  of  nature,  and 
become  acquainted  with  her  genuine  form;  nor  let  us 
imagine 
