Am.  Jour.  Pharm.  ) 
July,  1909.  / 
Assay  of  Volatile  Oils. 
thyme,  cinnamon,  and  turpentine ;  in  the  first  three  phenolic  com- 
ponents are  removed  by  shaking  with  alkalies,  in  the  fourth  the 
aldehydic  constituent  is  removed  by  shaking  with  sodium  bisulphite, 
and  in  the  last  the  terpene  is  removed  by  agitating  with  concentrated 
sulphuric  acid. 
As  in  all  cases  where  graduated  apparatus  is  used,  it  becomes 
necessary  to  verify  the  capacity  and  the  graduation  of  the  bottles 
used  for  centrifugal  work.  The  Babcock  milk  and  cream  bottles 
are  so  graduated  that  with  an  initial  weight  of  18  grammes  the 
graduations  give  at  once  percentage  by  weight  of  the  fat,  therefore 
it  is  not  to  be  expected  that  the  divisions  of  the  graduated  part  will 
represent  simple  fractional  parts  of  a  cubic  centimetre.  The  milk 
bottles  were  found  to  hold  48.8  c.c.  up  to  the  graduated  neck,  the 
latter  2.32  c.c.  from  0-10  with  divisions  into  fifths,  therefore  the 
fifty  divisions  equal  2.32  c.c.  or  one  division  equals  0.046  c.c.  The 
cream  bottles  were  found  to  hold  46.4  c.c.  up  to  the  graduated  neck, 
the  latter  7.82  c.c.  from  0-40  with  divisions  into  halves,  therefore 
the  eighty  divisions  equal  7.82  c.c.  or  one  division  equals  0.09775  c.c. 
Hortvet  and  West  describe  two  forms  of  graduated  bottles, 
having  a  capacity  of  150  c.c.  to  the  graduated  part,  the  latter  5  c.c. 
divided  into  100  divisions,  so  that  with  an  initial  volume  of  50  c.c. 
each  division  will  indicate  0.1  per  cent,  by  volume.  One  of  these 
forms  is  used  for  oils  lighter  than  water  or  the  employed  reagents, 
the  other  for  oils  heavier  than  water  or  the  employed  reagents. 
The  bottles  cannot  be  used  with  the  ordinary  Babcock  apparatus, 
but  are  used  with  the  Bausch  and  Lomb  precision  centrifuge. 
The  following  experiments  were  made  using  the  Babcock  cream 
bottles  and  calculating  the  undissolved  oil  to  volume  percentage. 
Oils  of  Cloves,  Pimenta,  and  Thyme. — Mix  the  carefully  meas- 
ured oil  with  30-35  c.c.  alkali  solution,  cork  the  bottle,  shake  thor- 
oughly for  several  minutes,  add  sufficient  alkali  solution  to  bring 
the  mixture  well  up  into  the  graduated  part,  cork  and  whirl  in  the 
centrifuge  until  the  insoluble  oil  separates  as  a  clear  layer  (3  to  10 
minutes,  800-1000  revolutions  per  minute). 
In  some  of  the  first  experiments,  the  bottles  were  not  corked 
while  in  the  centrifuge  and  more  or  less  discrepant  results  were 
obtained,  but  after  corking  the  bottles  remarkably  constant  results 
followed. 
Oil  of  Cassia. — The  U.S. P.  method  of  using  solution  of  sodium 
bisulphite  was  unsatisfactory  as  an  emulsified  portion  separated 
