314  Japanese  Oil  of  Peppermint,  {^'^■^{1'^";^!^!"^' 
article  being  known  as  an  article  of  commerce,  while  it  was  equally 
unknown  to  chemists.  In  regard  to  adulteration,  there  is  no  resemblance 
between  the  two  substances — I  mean  the  one  referred  to  by  Oppenheim 
and  that  now  under  notice — because,  though  the  crystals  do  resemble 
in  appearance  the  so-called  adulterating  substance,  there  is  not  the 
slightest  trace  of  its  presence,  a  chemical  examination  indicating  that  the 
deposition  is  as  pure  as  the  oil  from  which  it  has  been  thrown  down. 
4.  Dr.  Attfield  refers  to  peppermint  camphor  under  the  name  of 
menthene,  believing  it  to  be  the  hydro-carbon  found  more  or  less  in 
nearly  all  varieties  of  peppermint  oil. 
5.  fVom  the  numerous  experiments  which  have  been  made,  such  as 
the  fusing  and  boiling  point,  solubility  (though  very  sparing)  in  water, 
ether,  alcohol,  bisulphide  of  carbon,  fatty  and  essential  oils,  etc.,  it 
appears  that  the  substance  now  shown  is  in  all  respects  identical  with 
that  submitted  by  Oppenheim  in  1862  to  the  Chemical  Society,  but 
free  from  any  adulterating  ingredient. 
6.  Dumas,  as  well  as  Oppenheim,  appears  to  have  operated  on  pep- 
permint camphor.  The  result  of  his  examination  corresponded  with 
that  of  Oppenheim  and  Attfield.  Dumas  used  the  crystals  obtained 
from  some  variety  of  American  oil,  and  found  the  formula  to  be 
CjqH^^O,  precisely  the  composition  given  by  the  other  chemists,  and 
further  confirmed  by  Mr.  Hanbury  in  his  "  Pharmacographia." 
So  much  for  the  solid  oil  and  its  known  history.  Before  remarking 
further  on  its  solubility,  or  comparing  it  with  the  liquid,  let  me  notice 
the  use  to  which  a  similar,  if  not  the  identical  preparation,  has  been, 
and  is,  I  understand,  still  put  to  in  some  foreign  countries. 
About  five  years  ago  Dr.  A.  Wright  communicated  to  the  "Lan- 
cet" that  when  in  China  he  became  acquainted  with  the  fact  that  the 
natives,  when  suffering  from  facial  neuralgia,  applied  oil  of  peppermint 
to  the  seat  of  pain  by  means  of  a  camel-hair  pencil,  and  with  decided 
success. 
In  1871,  Mr.  D.  Hanbury  seated  in  the  "  Pharmaceutical  Journal" 
that  oil  of  peppermint  was  distilled  at  Canton,  though  unacquainted 
with  the  plant  used  for  its  production. 
Some  months  thereafter  Prof.  Fllickiger  referred  to  a  notice  which 
had  appeared  in  the  "American  Journal  of  Pharmacy  "  confirming  the 
use  by  the  Chinese  of  the  oil  in  neuralgic  cases,  stating,  further,  that 
the  oil  was  much  used  for  this  purpose  in  San  Francisco  and  elsewhere, 
the  oil  being  put  up  in  small  oSS  bottles,  and  sold  as  "  Chinese  Med- 
