Amsl°Zm?Im-}  Menthol.  493 
phosphoric  chloride  and  light  petroleum,  a  monochloride,  C10H17C1, 
and  a  dichloride,  C10H18G2.  are  obtained.  The  monochloride  boils 
at  205-2080,  has  the  sp.  gr.  at  0°/o°  =  0-9833  and  at  i5°/i5° 
=  0970,  is  laevorotatory ;  in  a  thickness  of  50  mm.  \_a]D  =  -r3°°> 
of  75  mm.  [a]D  =  -f  450.  The  dichloride  boils  at  150-1550  under 
60  mm.  pressure,  and  has  the  sp.  gr.  at  o°/o°  =  1-0824  The 
monochloride  is  doubtless  formed  from  the  dichloride  by  the  loss  of  a 
molecule  of  hydrochloric  acid,  but  it  was  not  found  possible  to  remove 
the  second  molecule  from  the  monochloride.  When  bromine  is 
added  to  a  cooled  acetic  acid  solution  of  menthene,  menthene 
dibromide,  C10H18Br2)  is  formed.  It  is  a  rather  viscid  oil,  boiling  at 
167-1720  under  50  mm.  pressure,  and  with  the  sp.  gr.  at  0°/o° 
=  1  '445  3-  When  it  is  heated  with  alcoholic  potash  for  15  hours 
on  the  water-bath,  a  hydrocarbon  C10H16  is  obtained.  This  boils  at 
1 72 -1 740  (uncorr.),  has  an  odor  like  that  of  limonene,  and  the  sp. 
gr.  at  0°/o°  =0  8540  and  at  20°/20°  =  0-8408;  it  unites  with 
bromine  and  hydrochloric  acid. 
Terpine  hydrate,  C10H20O2  -f-  H20,  was  heated  for  20  hours  with 
strong  hydriodic  acid  on  the  water-bath.  The  products  were  an 
iodide,  C10H19T,  a  diterpene,  C20H32,  and  possibly  a  hydrocarbon, 
C]0T€1S,  b  >iling  at  167-1700.  The  diterpene  boils  at  320-3250, 
has  the  sp.  gr.  at  o°/o°  =  09521  and  at  20°/20°  =  09428, 
and  resembles  very  closely  in  its  properties  and  reactions  the  diter- 
pene obtained  from  menthone.  The  iodide  is  an  oil  with  an  odor 
like  that  of  naphthene  icdides ;  it  boils  at  138-1420  under  30  mm. 
pressure,  and  has  the  sp.  gr.  at  I5°/I5°  =  i'370.  When  it  is 
treated  with  silver  acetate,  ether  added,  and  the  whole  allowed  to 
remain  for  two  days,  an  acetate  is  obtained,  and  a  hydrocarbon, 
C10H1S,  boiling  at  168-1700.  This  latter  has  at  210  sp.  gr.  =  0  813 
and  refractive  index  [#]D  —  1*45339  corresponding  to  a  molecular 
refraction  of  45  89  (theory  for  one  double  bond  45  64).  The  ace- 
tate was  hydrolyzed  by  warming  it  with  the  theoretical  amount  of 
alcoholic  potash  on  the  water-bath.  The  alcohol,  C^H^O,  thus 
obtained  boils  at  210-2140,  and  has  an  odor  like  that  of  menthol, 
but  it  cannot  be-  got  to  solidify.  It  is  inactive,  and  has  the  sp.  gr. 
at  o°/o°  =  0-91 5 1  and  at  150/ 150  =  0-9063. 
Menthol  has  thus  been  shown  to  be  connected  with  the  naph- 
thenes  ;  the  particular  naphthene  obtained  from  it  must  have  a  ring 
of  6  carbon  atoms,  since  menthol  can  be  converted  into  cvmene. 
