226      Oil  of  Sandalwood,  Lavender  and  Thyme.    {Am  May?iSiarm" 
According  to  Gildemeister  and  Hoffmann,  lavender  oils  are  divided 
into  two  classes,  those  containing  at  least  36  per  cent,  of  esters  and 
those  containing  from  30  to  36  per  cent,  of  esters.  This  classification 
includes  only  the  finest  oils  from  certain  localities.  The  same 
authorities  say  that  an  oil  containing  less  than  30  per  cent,  of  esters 
is  mostly  adulterated.  This  latter  statement  is  probably  too  sweep- 
ing, because  it  is  well  known  that  oil  of  lavender  is  met  with  that 
contains  as  low  as  10  per  cent,  of  esters,  yet  is  not  adulterated  and 
ranks  extremely  high  in  quality. 
The  method  employed  for  estimating  the  esters  is  described  in  the 
latter  part  of  the  above  process  for  determining  santalol,  and  the 
chemical  reaction  is  represented  by  the  following  equation : 
C10H17O.COCH3  +      KOH     =     C10H17OH    +  CH3COOK. 
Linalyl  acetate  -j-  potassium  =       linalool      -f  potassium 
hydrate  acetate. 
The  molecular  weight  of  linalyl  acetate  is  19-6,  and  the  per  cent, 
of  ester,  x,  can  readily  be  calculated  by  the  following  formula : 
19-6  I 
X  =  '2 
y  represents  the  number  of  cubic  centimetres  of  semi-normal  alkali 
used  in  saponifying  z  grammes  of  oil. 
OIL  OF  THYME. 
There  appears  to  be  little  genuine  oil  of  thyme  on  the  market,  but 
can  be  obtained  if  desired.  Most  of  it  seems  to  be  adulterated  with 
turpentine.  This  is  especially  true  of  the  white,  which  seldom  con- 
tains as  much  as  5  per  cent,  of  phenol  bodies.  Genuine  oil  of  thyme 
has  been  found  to  possess  the  following  properties :  soluble  in  from  1 
to  2  volumes  of  80  per  cent,  alcohol,  specific  gravity  0  900  to  0-935 
at  1 50  C,  and  the  content  of  phenol  bodies  varies  from  20  to  30  per 
cent.    Several  oils  examined  of  late  gave  the  following  results : 
