306  Iodine  Absorption  of  Essential  Oils.  {Amju0nUe^imrm' 
Oil  of  cloves  (and  pimento)  I  placed  in  the  first  class  in  the  pre- 
liminary examination  as  absorbing  but  little  iodine,  and  was  much 
surprised  to  find  how  high  the  equivalent  was. 
It  appears  as  if  the  reaction  goes  on  much  more  slowly  than  is  us- 
ual. In  another  respect  these  oils  were  peculiar.  After  titrating 
with  the  hyposulphite  solution  the  chloroformic  solution  of  oil  is  us- 
ually colorless,  and  remains  so.  In  the  case  of  these  oils,  however,  it 
had  a  deep  orange-red  color.  The  cause  of  this  has  not  yet  been  as- 
certained. 
Two  results  of  examination  of  the  lavender  oil  are  interesting : — 
1.  The  absorption  equivalent  of  the  Mitcham  oil  from  the  English 
variety  of  Lavandula  vera  is  practically  identical  with  that  of  the  oil 
from  the  French  variety,  though  the  grower  informs  me  that  in  color 
and  habit  the  plants  differ  much  from  one  another. 
2.  It  is  noteworthy  that  the  number  obtained  in  a  50  per  Gent, 
mixture  of  French  and  English  lavender  oil  is  very  close  to  the  mean 
of  the  equivalents  of  the  component  oils  (actually  found  286*2,  theory 
for  equal  parts  284*7). 
The  results  of  the  lemon  oil  examination  are  suggestive.  It  is  com- 
monly stated  that  in  spite  of  the  assurances  of  the  makers  this  oil  as 
found  in  commerce  is  habitually  adulterated  with  a  prepared  turpen- 
tine. 
The  absorption  equivalent  of  lemon  oil  is  high,  but  not  so  high  as 
that  of  turpentine ;  and  it  is  a  fact  that  the  lowest  equivalent  in  these 
seven  samples  (328*3)  is  that  of  an  oil  that  was  specially  obtained  for 
me  three  or  four  years  ago  by  the  agent  in  London  of  some  manufac- 
turers, for  purposes  of  examination.  The  other  samples  (which  were 
offered  commercially)  are  all  distinctly  higher,  ranging  from  340*3  to 
355*1. 
The  oils  of  peppermint  and  of  Japan  field  mint  resemble  one  an- 
other somewhat  closely  in  their  equivalents,  being  about  50  per  cent. 
One  sample  of  American  peppermint,  said  to  have  been  prepared 
from  plants  procured  from  Mitcham  and  cultivated  in  America,  has  a 
much  lower  iodine  absorption  equivalent  (82)  than  either  of  the  other 
three  examined,  which  range  from  121*8  to  143*9.  Why  the  Ameri- 
can oil  equivalent  should  be  more  than  twice  as  high  as  the  English  I 
am  quite  unable  to  say. 
In  the  preliminary  examination  of  the  oils  of  peppermint  I  some- 
times found  that  after  standing,  the  chlorofom  having  in  part  evapo- 
