Am.  Jour.  Pharm.  | 
August,  1884.  j 
Menthol 
405 
MENTHOL. 
By  Prof.  Henry  Trimble. 
Under  the  name  of  "Peppermint  Camphor,"  and  " Solid  Oil  of 
Peppermint,"  menthol  appears  to  have  been  known  as  early  as  1829. 
Its  composition  and  some,  of  its  properties  were  investigated  by  Dumas, 
Blanchet  and  Sell,  and  AYalter,  with  the  result  that  they  closely  agreed 
on  its  composition,  but  differed  widely  concerning  the  fusing  point. 
These  investigations  were  on  the  camphor  from  American  peppermint, 
and  they  all  agreed  on  the  formula  C10H20O,  while  the  fusing  point 
varied  from  25°C.  to  36'5°C.,  boiling-point  from  208°C.  to  213°C. 
In  1862  Oppenheim  ("Jour.  Chem.  Soc,"  xv,  24)  described  a 
"Solid  Oil  of  Peppermint"  from  Japan,  the  product  of  Mentha 
arvensis,  and  for  which  he  proposed  the  name  of  menthol.  He  stated 
the  fusing  point  to  be  36 °C,  boiling  point  210°C. ;  and  the  following 
result  in  regard  to  composition : 
Japanese.  American  (Dumas).  Calculated  for  Ci0H20O. 
C  76-93  76-5  76'92 
H  13-40  13-1  12-82 
0   10-26 
Not  much  attention  appears  to  have  been  given  to  this  substance,  until 
mention  is  made  ("Am.  Jour.  Phar.,"  May,  1871)  of  the  use  of  Chinese 
or  Japanese  oil  of  peppermint  by  the  Chinese  of  California  for  neural- 
gia. Fluckiger  ("  Pharm.  Jour.,"  Oct.,  1871),  examined  some  of  this 
oil  and  obtained  menthol  from  it,  the  identity  of  which  with  the  men- 
thol from  M.  piperita  he  considered  "not  quite  satisfactorily  proved." 
In  1874,  Mr.  John  Moss  "Pharm.  Jour.,"  Nov.,  1874),  speaks  of 
the  arrival  in  London  of  both  the  solid  and  liquid  oil  from  Japan. 
He  found  the  fusing  point  of  the  solid  oil  to  be  39°C,  and  boiling 
point  215°C,  although  it  began  to  boil  at  210°C.  In  1876  Messrs. 
Beckett  and  Wright  ("Jour.  Chem.  Soc,"  xxix)  examined  this  same 
menthol  furnished  by  Mr.  Moss.  They  first  purified  it  by  solution  in 
weak  alcohol,  separation  as  an  oil  and  exposure  to  air  until  crystals 
formed.  These  crystals,  after  several  weeks'  exposure  to  air,  fused  at 
42°C,  and  boiled  at  212°C.    A  combustion  gave  the  following  result: 
Calculated.  Found. 
C  76-92  76-35 
H   12-82  12-91 
Since  then  menthol  from  Chinese  or  Japanese  oil  has  rapidly  gained 
