52  Oleum  Betuke  LentcB.  {"^'"^^'1882™* 
well  as  from  teaberry,  without  previous  maceration.  Sometimes  the 
bark  is  covered  with  ice  and  snow.  As  stated  before,  the  material 
is  generally  placed  in  the  still  the  night  previous  to  commencing  dis- 
tillation in  the  morning.  The  steam  generated  passes  up  through  the 
drug,  and  extracts  the  oil  in  its  upward  exit ;  but  only  about  one- 
third  of  the  bark  is  covered  with  water  in  the  still.  When  the  bark 
is  macerated  the  yield  is  about  20  per  cent,  larger. 
There  are  three  layers  of  bark  on  the  wood.  The  outer  thin  tissue 
contains  no  oil ;  the  next,  or  middle  layer,  is  of  a  greenish  color,  and 
likewise  contains  no  oil ;  the  inner  layer,  next  to  the  wood,  which  is 
much  thicker  than  the  others  and  more  spongy,  yields  the  oil.  Mr. 
Seidle  informs  me  that  during  the  month  of  October,  or  about  the 
time  the  leaves  fall,  little  if  any  oil  is  made,  on  account  of  the  small 
yield,  hardly  reaching  30  per  cent,  of  the  yield  of  any  other  month 
during  the  year.  The  bark  is  never  dried,  but  cut  up  and  placed  in 
the  still  in  its  green  condition,  and  the  oil  extracted. 
Water  running  from  the  coal  mines  cannot  be  used  in  the  distilla- 
tion, because  it  contains  sulphur  and  its  compounds,  which  seem  to 
act  very  destructively  on  the  yield,  causing  a  falling  olf  of  at  least  75 
per  cent. ;  that  is  to  say,  instead  of  obtaining  4  pounds  of  oil,  but  1 
pound  is  obtained,  and  this  of  a  bright  blood-red  color. 
The  yield  of  oil  from  birch,  using  the  whole  tree  in  a  green  state,  is 
5  pounds  from  a  ton  of  2,240  pounds,  or  0*23  per  cent.  The  yield 
obtained  from  wintergreen  herb  averaged  18  pounds  from  a  ton  of 
2,240  pounds,  or  about  0*80  per  cent. ;  but  the  latter  plant  is  consider- 
ably more  expensive  to  gather,  costing  at  the  lowest  calculation  about 
$30.00  per  ton,  and  in  this  locality  labor  cannot  be  procured  at  that 
price,  since  the  gathering  of  the  herb  is  very  tedious,  and  the  laborer 
can  scarcely  earn  sufficient  to  live  on. 
The  oil  of  Betula  lenta,  obtained  as  above  described,  is  entirely 
colorless,  of  a  strong  and  agreeable  aromatic  odor,  and  of  a  sweetish 
aromatic  taste.  I  have  found  it  to  have  a  specific  gravity  of  1'178, 
about  the  same  weight  as  oil  of  wintergreen.  The  oil  boils  briskly  at 
from  424°  to  436°,  and  the  boiling  point  rises  to  442°F.,  where  it 
remains  stationary ;  a  little  higher  than  that  of  oil  of  teaberry,  which 
is  said  to  be  431  °F.  The  oil  on  being  heated  to  })oiling,  changes  in 
color  from  colorless  to  a  light  reddish-brown. 
Like  oil  of  gauitheria,  Avith  ferric  chloride  in  water,  it  produces  a 
dark  violet  color,  and  with  a  concentrated  solution  of  soda  or  potash 
