310 
Oil  of  Erigeron  and  Fireiceed. 
Am.  Jour.  Pharm. 
June,  1887. 
Treating  the  oils  in  the  same  way  with  pure  sulphuric  acid,  the 
fireweed  changed  within  thirty  minutes  to  a  very  dull  brown,  the 
erigeron  to  a  bright  red  color. 
Upon  moistening  chloral  hydrate  with  the  oils,  there  was  very 
quickly  produced  in  the  erigeron  a  delicate  green  tint,  which  re- 
mained permanent  for  some  time.  With  the  fireweed  a  similar  but 
less  delicate  tint  was  produced,  disappearing  however,  within  a  few 
minutes.  (Peppermint  produced  with  chloral  hydrate  a  beautiful 
rose.) 
Further,  as  to  physical  characteristics,  both  oils  are  quite  alike  in 
oxidation,  since  resin  is  formed  rapidly  wit  hin  both  upon  exposure  to 
air.  There  is  fortunately  a  distinguishing  characteristic  in  the  resin 
of  the  two  oils,  that  of  erigeron  being  a  deep  brown  red,  imparting 
its  color  to  the  oil.  The  oxidation  of  fireweed  has  but  a  slight  effect 
on  its  color ;  indeed,  as  has  been  stated,  its  resinoid  when  separated 
is  of  itself  light  in  color.  Both  the  oils,  when  oxidizing,  deposit  a 
layer  of  resin  upon  the  sides  and  bottom  of  the  bottle,  differing  in  this 
respect  greatly  from  peppermint,  which  holds  the  resin  suspended  in 
the  oil. 
One  other  interesting  phenomenon  was  observed  which  I  will  men- 
tion in  closing.  This  happened  in  the  last  pound  obtained  in  the  rec- 
tification of  100  lbs.  erigeron.  The  bottle  containing  the  same  was 
set  aside  during  the  month  of  Xovember  last  for  future  investigation, 
remaining  in  a  cool  room,  but  exposed  to  the  action  of  the  light  during 
the  winter.  In  the  meantime  a  delicate  formation  had  spread  through 
the  oil  somewhat  resembling  the  aquatic  form  of  life  known  as  the 
sea-urchin.  An  effort  was  made  to  separate  this  from  the  oil,  and 
had  due  precautions  been  taken  by  maintaining  the  same  temperature 
throughout  the  process,  the  separation  might  have  been  accomplished ; 
but  the  structure  being  extremely  delicate,  was  dissolved  and  lost. 
The  same  bottle  is  still  retained  with  the  hopes  that  the  formation  may 
again  appear,  when  an  effort  will  again  be  made  to  separate  it. 
From  the  experiments  made  in  the  foregoing,  the  following  com- 
parisons between  the  two  oils  may  be  made,  and  the  following  con- 
clusions drawn : 
1.  Polarization.  Pure  oil  of  erigeron  in  the  natural  state  should 
not  polarize  nearer  the  zero  point  than  —  26,  nor  farther  than  —  60  ; 
rectified  oil  freed  from  resin  may  polarize  some  nearer  the  zero  point  than 
the  limit  given,  and  the  first  fractions  should  be  dextrogyre.  Pure 
