Am.  Jour.  Pharm.  \ 
December,  1899.  / 
Analysis  of  Essential  Oils. 
$.73 
a  white  almost  insoluble  mass  which  is  gradually  saponified  to 
sodium  salicylate  and  methyl  alcohol  on  heating,  while  the  corre- 
sponding potassium  compound  is  very  soluble  in  water;  upon  acidu- 
lation  of  the  fresh  solution  it  forms  again  methyl  salicylate,  while 
upon  standing  of  the  solution  the  ester-salt  becomes  likewise  saponi- 
fied. 
The  alkali  salts  of  the  higher  fatty  acids,  like  lauric,  myinstic 
and  palmitic  acid,  remain,  at  the  alkali  treatment,  partly  dissolved 
in  the  oil,  and  are  later  found  in  the  residue  from  the  steam  rectifi- 
cation. 
The  purified  alkaline  solution  is  then  acidulated  with  dilute  sul- 
phuric acid,  whereby  phenols  and  less  soluble  acids  and  phenols 
form  an  oily  layer  or  crystalline  masses;  that  part  which  remains  in 
solution  is  obtained  by  extraction  with  ether  or  distillation  with 
steam. 
The  mixture  of  acids  and  phenols  can  be  separated  by  shaking 
their  ethereal  solution  with  a  solution  of  sodium  bicarbonate,  which 
takes  up  only  the  acids,  while  sodium  carbonate  would  also  dissolve 
some  phenols,  like  eugenol,  etc. 
The  phenols  which  remain  after  evaporation  of  the  ether  can 
then  be  separated  by  fractional  distillation  and  identified  by  their 
usually  well  crystallizing  benzoates  (prepared  after  Schotten-Bau- 
mann's  method)  or  by  the  aldehydes  and  acids  which  'result  from 
the  oxidation  of  their  acetates  or  benzoates. 
Solid  acids  are  separated  by  methodic  crystallization  from  suitable 
solvents;  from  liquid  acids  the  dry  alkali  salts  are  prepared,  these 
latter  being  then  transformed  into  esters  by  boiling  with  alcohol 
and  sulphuric  acid  ;  the  resulting  esters  are  then  fractionated.  The 
fractions  of  constant  boiling  point  are  hereafter  saponified,  then  the 
silver  salts  prepared  from  the  neutral  solutions  and  analyzed  by 
combustion. 
In  many  oils  which  contain  bodies  with  hydroxyl  groups  (alco- 
hols and  phenols),  part  of  these  latter  are  present  as  esters,  chiefly 
esters  of  acetic  acid ;  but  also  butyric,  valerianic,  benzoic,  cinna- 
mylic  and  other  esters  are  found  occasionally.  To  the  groups  of 
esters,  in  their  chemical  behavior  being  quite  similar  to  them,  the 
lactones  may  be  counted,  which  are  quasi  inner  esters,  the  carbo- 
xylic  and  hydroxylic  groups  which  have  combined  under  formation 
of  water  belonging  to  the  same  molecule.    To  test  an  oil  for  the 
