328 
Assay  of  V olatile  Oils. 
Am.  Jour.  Pharm. 
July,  1909. 
below  the  insoluble  oil  constituent,  making  the  reading  of  the  latter 
almost  impossible. 
By  using  a  saturated  sodium  sulphite  solution  in  presence  of  a 
few  drops  of  phenolphthalein  indicator  and  neutralizing  the  liberated 
Oil. 
C.c. 
taken. 
Reagent. 
Undissolved  Oil. 
Volume  Per  Cent. 
Vol.  Per  Cent, 
by 
U.  S.  P. 
Process. 
Divisions. 
C.c. 
Insoluble 
Oil 
Phenols. 
4-9 
Wfc  KOH 
8 
0.782 
15-9 
84.I 
82. 
4-9 
10J6  KOH 
8 
0.782 
15-9 
84.I 
4-9 
iofo  KOH 
7 
0.68425 
13-9 
86.1 
84'. 
9.8 
io$  KOH 
1-3685 
13-9 
86.1 
4-9 
loii  KOH 
44 
4.301 
87.7 
12.3 
II. 
4-9 
io#  KOH 
44 
4.301 
87.7 
12.3 
4-9 
io0  NaOH 
44 
4.301 
87.7 
12.3 
sodium  hydroxide  with  acetic  acid  (36  per  cent.),  much  better 
results  were  obtained  although  the  insoluble  oil  was  dark  and  viscid. 
The  process  adopted  after  numerous  experiments  was  as  follows : 
Mix  the  carefully  measured  oil  with  an  equal  volume  of  oil  of 
turpentine,  add  30  c.c.  saturated  solution  of  sodium  sulphite,  cork 
bottle,  warm  in  water-bath  for  10-15  minutes,  agitate  repeatedly, 
acidify  with  acetic  acid  (36  per  cent),  add  sufficient  sodium  sulphite 
solution  to  bring  the  mixture  well  up  into  the  graduated  part,  cork 
bottle,  whirl  until  the  insoluble  oil  separates  as  a  clear  layer,  cool, 
and  read  off  volume  of  insoluble  oil.  Make  a  blank  test  with  the 
same  volume  of  oil  of  turpentine  and  take  the  difference  in  reading 
between  the  two  tests. 
Oil. 
C.c. 
taken. 
Undissolved  Oils. 
Volume  Per  Cent. 
Vol.  Per  Cent. 
by 
U.  S.  P. 
Process. 
Mixture 
Divisions 
Blank 
Divisions 
Cassia 
Divisions 
C.c. 
Insoluble 
Oil. 
Aldehyde 
2  C.C. 
3  c.c. 
2  C.C. 
each 
3  c.c 
each 
24.5 
36.5 
20.5 
30,5 
20.5 
30.5 
4- 
6. 
Cassia-Turpentine  
0.391 
0.5865 
19-55 
19-55 
80.45 
80.45 
about  75 
about  75 
Experiments  are  now  under  way  to  determine  if  other  volatile 
oils  can  be  determined  by  the  aid  of  the  centrifuge. 
