550  Japanese  Peppermint  Camphor.  {^'^'ilc'\ljs^' 
JAPANESE  PEPPERMINT  CAMPHOR.* 
BY  G.  H.  BECKETT  AND  C.  R.  ALDER  WRIGHT,  D.  SC. 
Lecturer  on  Chemistry  in  St.  Mary's  Hospital  Medical  School. 
Through  the  kindness  of  Mr.  John  Moss  (Messrs.  Corbyn  and  Co.) 
we  have  received  a  Hberal  supply  of  well  crystallized  Japanese  pepper- 
mint camphor,  and  also  of  the  liquid  camphor  oil  simultaneously  im- 
ported, the  crystals  being,  in  fact,  the  stearopten  of  the  oil,  separated 
from  the  liquid  constituents  by  standing  and  pressure.  This  crystalline 
camphor  has  been  already  examined  by  Oppenheim  {Chem.  Soc.Journ.  [i], 
XV.,  24),  who  found  that  it  contains  more  hydrogen  than  ordinary  cam- 
phor, being  indicated  by  the  formula  C^oHgoO — ordinary  camphor  being 
C^^H^gO — and  that  it  is  a  kind  of  monatomic  alcohol,  menthylic  alcohol^ 
forming  a  hydrocarbon,  menthene^  Cj^H^g,  by  the  action  of  dehydrating 
agents,  just  as  ordinary  alcohol  gives  rise  to  ethylene. 
This  alcohol,  being  homologous  with  allylic  alcohol,  is  manifestly 
more  closely  connected  with  the  "  fatty  "  or  methylic  alcohol  series 
than  with  benzene  derivatives  ;  whilst  the  hydrocarbon  menthene  is  just 
midway  between  the  lo-carbon  marsh  gas  homologue  and  cymene, 
thus  : 
Decane,   C10H22 
Decylene,  ..........  C10H20 
Menthene,  CioHis 
Terpenes,  ..........  C10H16 
Cymene,        .       .        .       .       .        .       .       .       .        .  C10H14 
It  is,  therefore,  of  some  interest  to  see  whether  cymene  is  obtainable 
from  menthene,  and  hence  from  menthylic  alcohol,  by  simple  treatment 
— /.  whether  these  substances  are  not  connecting  links  between  the 
fatty  and  aromatic  series. 
Oppenheim  found  the  melting  point  of  menthylic  alcohol  to  be,36^  ; 
the  crystals  sent  to  us  were  found  by  Mr.  Moss  to  melt  at  39°,  re-so- 
lidifying at  37*^.5  ;  on  dissolving  them  in  hot  dilute  alcohol  no  crystals 
deposited  on  cooling,  but  an  oily  fluid  separated  ;  this  gradually  became 
crystalline  as  the  traces  of  alcohol  retained  by  it  evaporated,  and  after 
exposure  to  air  for  several  weeks,  was  found  to  melt  at  42°,  and  to  boil 
at  212°  (corrected — Oppenheim  found  210°  and  Mr.  Moss  215°):  on 
analysis  numbers  were  obtained  agreeing  sharply  with  the  formula 
The  crystals  were  heated  with  about  their  own  weight  of  zinc  chlo- 
*  Read  before  the  British  Pharmaceutical  Conference. 
