220  Adulteration  of  Volatile  Oils.  {Am,Maya908?rm' 
unfortunately,  the  present  official  method  gives  too  high  results  in 
the  presence  of  chloroform.  The  main  difficulty  in  using  this 
adulterant  is  in  adding  an  excessive  quantity  when  the  indicated 
per  cent,  of  santalol  will  be  above  100  per  cent.  In  one  case  166  per 
cent,  of  santalol  was  indicated  by  adding  I  part  of  chloroform  to 
7  parts  of  oil,  the  optical  rotation  of  this  admixture  was — 170  I2;, 
specific  gravity  rc>33,  and  it  was  soluble  in  two  volumes  of  70  percent, 
alcohol.  Wielen  (Chendker  Zeitung)  has  offered  an  improvement  in 
the  manipulation  of  the  assay  by  substituting  a  10  per  cent,  solu- 
tion of  sodium  chloride  for  the  water,  by  which  time  is  saved  and 
much  less  oil  is  lost  by  emulsification. 
It  would  be  unwise  for  our  Pharmacopoeia  to  give  a  wider  range 
to  the  constants  of  this  oil,  even  if  some  injustice  is  done  by 
excluding  some  pure  oils.  The  comparative  narrow  limits  render 
adulteration  more  difficult. 
OLEUM  SASSAFRAS. 
The  main  adulterant  of  this  oil  is  a  certain  fraction  of  ca'mphor 
oil.  The  detection  is  exceedingly  difficult,  providing  the  manufac- 
turer does  not  take  too  large  a  fraction  and  increase  the  specific 
gravity  above  the  limit.  One  chemist  has  reported  the  finding  of 
camphor  in  the  oil,  no  doubt  due  to  a  small  amount  present  in  the 
camphor  oil  used  for  adulteration. 
Many  other  specific  cases  might  be  considered,  but  in  general 
a  comparative  odor  test  with  a  sample  of  known  purity  is  a  very 
satisfactory  way  of  valuation.  Place  equal  amounts  of  the  oils  on 
filter  papers  in  the  bottom  of  small  jars  or  beakers,  and  carefully 
consider  the  delicacy  of  the  odors  until  evaporation  is  complete* 
The  odor  of  the  natural  oil  is  very  persistent.  One  authority  states 
that  ^  0T0  0  of  a  milligramme  of  mint  can  be  detected  in  one  quart 
of  air.  As  a  rule  pure  oils  will  retain  their  same  fundamental  odor 
until  the  end  of  the  experiment,  while  an  adulterated  or  synthetic 
oil  will  pass  through  a  series  of  variations  depending  on  the  nature 
of  the  mixture.  Another  peculiarity  of  true  oils  is  that  they  will 
impart  their  characteristic  odor  to  a  larger  volume  of  liquid  than 
their  substitutes.  A  satisfactory  odor  dilution  test  can  be  made  by 
dissolving  1  c.c.  of  the  oil  in  100  c.c.  of  alcohol,  1  c.c.  of  this  is 
added  to  99  c.c.  of  dilute  alcohol,  and  1  c.c.  of  this  dilution  added 
