484 
Oils  of  Peppermint  and  Spearmint. 
Am.  Jour.  Pharm. 
Oct.,  1885. 
WHAT  IS  THE  CHEMICAL  RELATION,  if  any,  BETWEEN 
THE  OILS  OF  PEPPERMINT  AND  SPEARMINT? 
By  Henry  Teimble. 
Read  before  the  American  Pharmaeeutieal  Association. 
In  answering  this  query  it  is  necessary  to  assure  the  Association 
that  the  following  experiments  were  made  on  pure  oils.  The  purity 
of  the  samples  was  vouched  for  in  every  case  by  those  who  were  per- 
sonally acquainted  with  tlieir  manufacture. 
Sufficient  investigation  has  already  been  made  of  spearmint  oil  to* 
prove  that  it  is  different  from  oil  of  peppermint,  consequently  attention 
has  been  directed  to  determining  whether  there  is  ani/ chemical  relation 
between  them,  and  at  the  same  time  corroborating  the  work  already 
done  by  others. 
History. — Oil  of  spearmint  appears  to  have  been  correctly  analyzed 
by  Gladstone  ("  Journal  of  Chemical  Society,'^  1864),  who  stated  that  it 
consisted  of  a  terpene,  C\oHie,  and  carvol,  CjoHj^O.  He  separated  them 
by  fractional  distillation,  and  by  precipitating  carvol  by  means  of 
alcoholic  ammonium  sulphide. 
The  result  is  a  mass  of  beautiful  acicnlar  crystals,  readily  purified 
by  solution  and  recrystallization  from  hot  alcohol,  and,  when  pure, 
free  from  odor,  composed  of  (CioHj40)2H2S.  This  compound  decom- 
posed by  ammonia  yields  carvol,  which  has  an  odor  resembling  spear- 
mint, although  distinct  from  it.  With  the  exception  of  the  odor  this 
carvol  appears  to  be  identical  with  that  from  the  oils  of  caraway,  dill 
and  nutmeg.  The  oil  examined  by  Gladstone  showed  a  specific  gravity 
at  14-5°C.  of -9105. 
Experiments  on  Oil  of  Spearmint. — Three  samples  were  kindly  fur- 
nished me  by  Mr.  Albert  M.  Todd,  the  well-known  manufacturer  of 
pipmenthol.  1.  A  light  fraction.  2.  A  heavy  fraction,  and  3.  Ther 
natural  oil.  The  light  portion  boiled  at  174°C.,  had  a  specific  gravity 
of  '9078  at  15°C.,  and  failed  to  deposit  any  crystals,  except  water,  at 
—  23°C. 
It  was  distilled  under  reduced  pressure  with  a  two  ball  fractioning 
tube.  The  light  portion  of  this  process  was  repeatedly  rectified  in  the 
same  way  until  a  product  was  obtained  of  specific  gravity  '866  at 
15°C.,  and  boiling  at  160°  to  165°C.  This  was  found  on  combustion 
to  contain  over  three  per  cent,  of  oxygen.    The  odor  of  spearmint  had 
