^™"juiy?if88^''°'"}      Distillation  of  Peppermint  Plants.  329 
Michigan  being  twentv-five  cents  for  each  pound  of  essential  oil. 
This  custom  is  most  satisfactory  to  the  grower,  as  he  pays  only  ac- 
*  cording  to  his  receipts,  but  it  will  be  seen  that  it  is  not  equitable  for 
the  distiller  unless  the  plants  are  well  dried  prior  to  distillation. 
The  manufacturing  system  may  be  briefly  noticed  as  follows  : 
the  plants  having  been  cut  when  in  full  bloom,  are  drawn  to  the 
distilleries  either  with  or  without  curing,  according  to  the  notion 
of  the  grower.  The  essential  features  of  the  distillery  are,  first,  a 
large  boiler  for  the  generation  of  steam ;  second,  a  pair  of  large 
wooden  vats,  about  six  feet  in  height  and  of  equal  maximum  diam- 
eter, which  are  connected  with  the  boiler  by  steam-pipes,  which  enter 
them  at  the  bottom,  [two  vats  being  used  so  that  one  may  be  emptied 
and  refilled  while  the  other  is  running]  ;  third,  a  condensing  appar- 
atus, which  consists  of  a  series  of  pipes  coated  with  pure  tin,  either 
with  or  without  the  ordinary  "  worm"  over  which  cold  water  is  made 
to  flow  continuously,  this  condensing  apparatus  being  connected  with 
the  top  of  the  distilling  vats  at  pleasure  by  a  duplex  or  changing 
vaUV  ;  lastly,  is  the  "  receiver'^  in  which  the  essential  oil  is  collected, 
the  ordinary  form  of  which  is  a  metallic  vessel,  about  twelve  inches 
in  diameter  and  three  feet  in  height,  from  the  bottom  of  which  an  ex- 
terior pipe  leads  to  a  height  nearly  equal  with  the  body  of  the  re- 
ceiver. Recently  I  have  constructed  a  much  more  efficient  and  elab- 
orate receiver  for  rapidly  separating  essential  oils  both  heavier  and 
lighter  than  water  ;  but  as  this  paper  is  not  intended  as  a  technical 
treatise  on  apparatus,  it  will  not  be  described  here. 
About  three  inches  from  the  bottom  of  the  distilling  vats  are 
placed  "  false  bottoms,"  containing  many  perforations,  underneath 
which  the  steam  enters  from  the  boiler.  Upon  this  perforated  false 
bottom  is  placed  a  strong  iron  hoop,  having  a  diameter  nearly  equal 
with  the  vat  and  supplied  with  heavy  cross-bars.  Two  pairs  of  strong 
chains  are  secured  to  this  hoop,  meeting  at  the  top  of  the  vat  in  a  pair 
of  rings,  one  of  which  is  fastened  on  either  side  of  the  vat  at  the  top 
T^vhile  it  is  being  filled.  This  apparatus,  as  will  be  seen,  is  for  the 
purpose  of  drawing  the  charge  from  the  vats  after  distillation. 
The  apparatus  being  in  position,  the  plants  are  thrown  in  by  a 
workman  with  an  ordinary  hay-fork,  while  two  or  three  others  are 
engaged  in  tramping  them  down."  After  the  vat  is  about  one-third 
full,  a  small  supply  of  steam  is  let  in,  which  softens  the  plants  and 
greatly  assists  in  packing.    When  filled,  the  vat  is  closed  with  a 
