^"'•juiy^ifss^'''^'}  Distillation  of  Peppermint  Plants.  331 
The  first  charge  of  peppermint,  which  was  distilled  in  the  green 
state,  weighed  2332  lbs.  and  produced  6  lbs.  9  oz.  of  essential  oil, 
being  one  pound  of  oil  for  each  355*35  lbs.  of  plants,  or  0*2814  per 
cent.  After  the  second  load  had  been  dried  and  exposed  to  the 
atmospheric  action  as  stated,  for  a  little  over  six  months,  it  was  taken 
from  the  loft  and  distilled.  I  would  say  here  that  all  the  oil  in  the 
peppermint,  as  indeed  in  most,  if  not  all,  essential  oil  plants,  is  obtained 
from  the  leaves  and  blossoms.  However,  in  distilling,  the  yield  was 
more  than  one  pound  of  essential  oil  for  each  362*5  lbs.  of  original 
green  plants,  which  slight  loss  (about  two  per  cent,  in  the  amount 
of  essential  oil),  is  certainly  to  be  accounted  for  by  the  portion  of 
leaves  and  blossoms  which  rattled  off  in  the  re-handlings.  The  charge 
of  peppermint,  which  was  thus  fully  dried,  had  shrunk  49*4  per 
cent,  of  its  original  weight. 
It  will  thus  be  seen  that  although  the  plants  are  very  aromatic  both 
before  and  after  cutting,  there  is  no  perceptible  loss  of  the  essential 
oil  by  a  thorough  drying  of  the  plants  prior  to  distillation,  the  oil 
being  so  tightly  sealed  in  its  little  prison  cells  that  a  force  greater  than 
that  existing  in  the  atmosphere  or  the  rays  of  the  sun  is  necessary  to 
free  it.  Indeed,  I  have  noticed  that  the  leaves  which  fall  from  the 
plants  in  dry  seasons  and  remain  upon  the  ground  over  winter,  even 
though  subjected  to  rains  and  snows  as  well,  are  often  found  months 
afterward  to  be  so  strong  that  one  would  hardly  suppose  that  any  of 
the  strength  had  passed  off.  It  is  known  though  in  practical  experi- 
ence that  when  the  plants  are  once  dried  and  subjected  to  rains,  the 
water  carries  of  a  portion  of  the  oil,  acting  in  that  respect  as  a  slight 
distilling  force. 
It  is  not  within  the  scope  of  the  present  article  to  treat  of  the 
chemical  effect  produced  upon  the  oil  by  the  action  of  the  atmosphere, 
the  tests  of  the  oil,  etc.  Such  determinations  may  be  found  by  con- 
sulting the  papers  referred  to  in  the  note  below.  The  principal  results 
of  the  experiments  recorded  herein  may  be  summarized  as  follows : 
First. — ^^In  the  treatment  of  peppermint  and  such  other  American 
essential  oil  plants  as  have  been  examined,  no  perceptible  loss  of  the 
essential  oil  by  diffusion  in  the  atmosphere  is  occasioned  by  a  thor- 
ough drying  of  the  plants  prior  to  distillation,  in  the  open  air  at  any 
ordinary  temperatures. 
Second. — When  the  drying  of  the  plants  is  continued  through  many 
months,  a  slight  oxidation  of  the  oil  in  the  leaf  occurs  through  con- 
