540  Oils  of  Anise.  {AnuKiS?rm- 
OILS  OF  ANISE.1 
By,  P  W.  Squire,  F.L.S. 
As  supplementary  to  the  paper  read  by  Mr.  John  C.  Umney 
(Am.  Journ.  Pharm.,  1889,  p.  255),  and  the  ensuing  discussion,  the 
following  rough  notes,  arising  out  of  some  experiments  in  connec- 
tion with  a  new  edition  of  the  «•  Companion  to  the  B.P.,"  may  help 
towards  a  more  accurate  knowledge  of  these  oils. 
It  may  be  premises  that  the  oil  of  ordinary  anise  (Pimpinella 
Anisuni)  and  of  star  anise  {lllicium  anisatum),  when  freshly  distilled, 
consists  mainly  of  anethol,  a  stearopten  melting  at  700  F.,  with  vary- 
ing quantities  of  a  terpene.  By  exposure  to  air,  anethol  is  gradually 
converted  into  anisic  aldehyde,  with  probably  some  resinification  of 
the  terpene,  this  oxidation  being  accompanied  by  certain  changes 
in  the  physical  characters  of  the  oil. 
In  connection  with  the  solidification  and  liquefaction  of  anise  oil, 
there  are  three  temperatures  to  be  noted  : 
(A.)  "  Abnormal  solidifying  point,"  or  the  temperature  at  which 
the  oil  when  cooled  first  shows  indication  of  freezing.  This  depends 
so  completely  upon  conditions  of  cooling  that  no  figure  can  be 
attached  to  it.  Two  experiments  with  the  same  sample  may  show 
a  difference  of  over  200  F.,  this  being  true  of  either  variety  of  oil. 
(B.)  "  Normal  solidifying  point."  This  is  defined  by  Mr.  Umney 
as  "  the  temperature  to  which  the  thermometer  immediately  rises  on 
solidification  taking  place."  For  two  reasons  this  point  is  some- 
what indefinite  .  (1)  the  rise  in  temperature  is  more  or  less  gradual, 
and  although  much  more  rapid  at  first  than  at  the  finish,  the  ther- 
mometer is  never  steady  at  any  one  point,  and  the  more  solid  the 
frozen  mass,  the  slower  the  rise  in  the  thermometer  ;  (2)  the  point 
to  which  the  temperature  rises,  rapidly  depends  to  some  extent 
upon  how  far  the  oil  has  previously  been  cooled.  Supposing  one 
considers  the  normal  solidifying  point  to  be  reached,  when  the  rise 
of  temperature  is  only  one  degree  in  half  a  minute,  a  difference  of 
200  in  the  abnormal  may  make  a  difference  of  30  to  6°  in  the  normal 
solidifying  point. 
(C.)  "  Melting  point."  The  temperature  at  which  a  sample  after 
freezing  becomes  completely  liquid  is  the  only  constant  factor  in 
connection  with  the  congelation  and  liquefaction  of  anise  oils.    It  is 
1  Reprint  from  Pharm.  Journ.  and  Trans.,  p.  104,  Aug.  5,  1893. 
