Am.  Jour.  Pharni. 
Sept.,  1892. 
Menthol. 
491 
since  the  latter  volatilize  and  decompose  on  evaporation  to  dryness, 
as  the  odor  of  the  escaping  vapors  evidences. 
For  this  purpose  the  free  acid  in  the  sulphuric  acid  solution  was 
nearly  neutralized  with  soda,  evaporated  nearly  to  dryness.  Then 
finally  neutralized  and  evaporated  to  complete  dryness.  By 
treatment  of  the  residue  with  nearly  absolute  alcohol  only  the 
organic  salts  go  into  solution;  the  alcoholic  solution  is  therefore 
filtered  from  the  sulphate  of  sodium,  evaporated  to  dryness  and 
weighed.    The  result  gives  the  amount  of  bases  present  as  sulphates. 
In  the  foregoing  pages  we  have  sketched  an  analytical  process 
for  coal-tar  preparations  which  has  given  accurate  and  reliable 
results  in  our  hands,  and  admits  of  a  more  complete  examination  of 
the  products  than  the  methods  hitherto  connectedly  published. 
We  hope  that  the  information  will  prove  valuable  at  the  present 
time  in  aiding  anyone  examining  and  comparing  the  various  coal- 
tar  disinfectants  in  coming  to  correct  conclusions  as  to  their  respec- 
tive composition  and  the  percentage  of  cresols  on  which  depends 
the  value  of  the  preparation  as  a  disinfectant. 
MENTHOL.1 
By  A.  Berkenheim. 
When  menthol,  C10Hl9OH,  is  added  in  successive  small  portions 
to  a  carefully  cooled  mixture  of  phosphoric  chloride  and  light  petro- 
leum, there  is  formed  from  100  grams  of  menthol  (1)  70  grams  of 
menthyl  chloride,  C10H19C1,  an  optically  inactive  liquid  boiling  at 
209-5-2 10-5°  (uncorr.),  and  having  the  sp.  gr.  at  0°/o°  =  0-9565 
and  at  iS°/lS°  =  0-947,  an^  (2)  15  grams  of  a  menthene,  C10H18, 
boiling  at  167-1690  (uncorr.).  This  menthene,  when  warmed  with 
phosphoric  chloride,  yields  a  chloride,  C10H17C1,  boiling  at  204-208 °. 
Menthyl  chloride  is  not  affected  by  zinc  and  hydrochloric  acid,  and 
is  converted  by  zinc  dust  and  acetic  acid  into  the  above-mentioned 
menthene  ;  but  it  is  reduced  when  heated  for  30  hours  at  200°  with 
hydriodic  acid  and  phosphorus  in  a  sealed  tube.  Menthonaphthene , 
C10H20,  boiling  at  169-170-5°,  is  thus  obtained.  It  is  an  inactive 
liquid,  possessing  only  a  feeble  odor  when  pure,  and  the  sp.  gr.  at 
1  BerichU,  25,  686-698  ;  Jour.  Chem.  Soc,  1892,  p.  866. 
