308  Oil  of  Ei-igeron  and  Fireweed.  {Ava'ATJ;mi&xm' 
Taking  now  the  eighteen  fractions  of  each  oil  united  in  equal  parts 
by  weight,  the  following  results  were  obtained  : 
ERIGERON.  FIRE  EED. 
Temperature  F.  Sp.  Gr.  Temperatu  *e  F.  Sp.  Gr. 
40°  -878  40°  -867 
60°  -86975  60°  -.85925 
80°  -8603  80°  -8501 
It  will  thus  be  seen  that  the  rectified  fireweed  is  about  '011  lighter 
than  erigeron.  In  this  test,  however,  the  last  3  pounds  obtained  from 
the  erigeron  was  not  used,  being  rank  in  odor.  Had  this  been  used 
to  fairly  represent  the  fresh  oil  in  a  state  of  purity,  it  would  have 
raised  the  sp.  gr.  about  .001,  so  that  it  is  safe  to  say  that  the  density 
of  fireweed  under  the  same  conditions  of  freshness  as  erigeron,  is  about 
.011  to  .012  lighter. 
It  will  be  noticed  that  the  first  15  fractions  of  fireweed  average 
about  '035  lighter  than  the  same  fractions  of  erigeron.  Fractions  16 
and  17  when  united  are  about  equal.  The  18th  fraction  of  fireweed 
is  somewhat  heavier  than  the  corresponding  one  of  erigeron,  and  nearly 
though  not  quite  so  heavy  as  the  equivalent  last  portions  obtained 
from  the  erigeron  when  proportionately  united. 
A  distinct  test,  and  easy  in  the  hands  of  the  pharmacist,  is  here 
obtained ;  that  when  erigeron  is  fractionally  distilled  in  the  presence 
of  water  and  divided  in  fractions  either  of  20  or  2,  the  first  portion 
recovered  will  not  vary  from  "860.  When  fireweed  is  treated  in  like 
manner,  the  first  portion  (no  matter  how  many  the  fractions)  will  not 
be  far  from  *826.  And  this  wide  difference  is  certainly  sufficient  to 
identify  the  one  from  the  other. 
As  a  phenomenal  feature  in  the  polarization  of  the  fractions  of  eri- 
geron, it  will  be  noticed  that  while  the  oil  originally  operated  upon 
was  strongly  lsevogyre  (polarizing  —  50'5°)  the  first  14  fractions  are 
actively  dextrogyre,  and  the  15th  neutral;  with  the  16th  a  laevogyre 
rotation  is  shown  of  3°,  which  tendency  is  rapidly  augmented  in  the 
17th  fraction  by  an  increase  of  32°,  finally  reaching  in  the  18th  a  point 
—  43*5.  These  18  fractions  when  united  polarize  at  —  28°. 5. 
The  first  3  fractions  from  oil  of  fireweed  are  lsevogyre ;  the  rotation 
changes  in  the  4th  to  dextrogyre,  which  is  continued  until  the  8th  frac- 
tion is  reached,  when  the  left-handed  rotation  again  occurs.  The  9th 
is  nButral ;  with  the  iOth  the  dextrogyre  rotation  is  shown,  which  is 
continued  until  the  16th,  when  the  direction  is  suddenly  changed  again 
to  the  left  by  a  reversion  from  +  2  to  —  9.    The  rotatory  activity  in 
