224      Oil  of  Sandalwood,  Lavender  and  Thyme.  {AmMJa0"tri9oiharini 
some  of  the  celebrated  English  lavender  oils  contain  but  a  low  per 
cent,  of  ester,  which  would  indicate  that  the  ester  is  not  the  only 
factor  to  be  considered  in  selecting  an  oil.  In  fact  it  happens 
occasionally  that  the  nose  and  the  per  cent,  of  ester  are  entirely  at 
variance  with  each  other  on  oils  obtained  from  the  same  locality. 
During  the  past  year  the  writer  has  had  occasion  to  examine  a 
goodly  number  of  the  above  oils  and  herewith  gives  the  results  of 
his  work. 
OIL  OF  SANDALWOOD. 
This  oil  is  probably  looked  on  with  more  suspicion  than  any 
other.  It  is  claimed  by  some  that  in  order  to  be  sure  of  getting 
the  genuine  article  it  was  necessary  to  resort  to  manufacturing  it 
themselves.  The  writer's  experience  has  been  that  reliable  manu- 
facturers handle  the  genuine  article.  That  an  oil  is  pure  can  readily 
be  determined,  for  the  physical  and  chemical  constants  have  been  so 
thoroughly  worked  out  that  there  cannot  be  much  doubt  of  their 
reliability  ;  these  are,  specific  gravity  at  150  C,  0  97  to  0-978,  readily 
soluble  in  five  volumes  of  70  per  cent,  alcohol,  optical  rotation  from 
—  17  to  190  at  25 0  C.  in  a  100  millimetre  tube,  santalol  at  least  90 
per  cent. 
Sample  No.  1,  in  the  table  following,  was  made  by  the  writer  from  a 
wood  that  yielded  5-5  per  cent,  of  oil,  and  it  can  readily  be  seen  that 
the  constants  obtained  fall  well  within  the  above  limits.  The 
methods  for  obtaining  the  above  constants  are  simple  and  easily 
available,  except  the  one  for  estimating  the  santalol,  which  will  be 
given  here. 
Into  a  flask,  provided  with  a  reflux  condenser,  place  20  grammes 
of  the  oil,  add  an  equal  volume  of  acetic  anhydride  (not  anhydrous 
acetic  acid)  and  2  grammes  of  fused  sodium  acetate;  then  gently 
boil  for  about  two  hours.  Wash  the  mixture  first  with  water,  then 
with  a  solution  of  sodium  hydrate,  then  with  water  again  ;  finally 
dry  the  resulting  oil  with  anhydrous  sodium  sulphate.  Of  this  dried 
product,  place  from  2-5  grammes  into  a  flask  provided  with  a  reflux 
condenser,  add  an  excess  of  normal  alcoholic  potassium  hydrate,  and 
boil  for  half  an  hour.  Ascertain  the  amount  of  alkali  consumed  by 
titrating  back  the  excess,  with  normal  sulphuric  acid.  From  the 
data  thus  obtained  the  amount  of  santalol  is  readily  calculated 
by  the  following  formula: 
P  =       a  X  22-2 
s  —  (ax  0042) 
