AmsSt.a836arm'}  Saponification-Equivalents  of  Fixed  Oils.  433 
be  deemed  an  adulteration.  For  its  determination  the  suspected 
ceresin  should  be  dissolved  in  hot  alcohol,  and  the  mixture  then 
cooled  and  filtered.  The  ceresin  being  almost  insoluble  in  cold  alco- 
hol is  removed,  and  any  resin  present  will  be  found  in  the  residue 
upon  evaporation  of  the  filtrate. — Phar.  Jour,  and  Trans.,  July 
31,  p.  90.   
ON  THE  SAPONIFICATION-EQUIVALENTS  OF 
FIXED  OILS. 
By  Alfred  H.  Allen,  F.I.C.,  F.C.S. 
Read  before  the  Society  of  Public  Analysts,  June,  1886. 
The  saponification-method  of  examining  fatty  oils,  originally  ap- 
plied by  Koettstorfer  to  the  examination  of  butter,  has  been  employed 
by  various  chemists  for  differentiating  other  oils,  and  has  proved  one 
of  the  most  valuable  methods  of  analysis  yet  devised. 
The  practical  value  of  the  indications  of  Koettstorfer's  process 
largely  depends  on  the  accumulation  of  evidence  as  to  the  limits  of 
variation  of  neutralizing  powers  exhibited  by  different  samples  of  oil 
of  the  same  kind,  and  hence  I  have  been  at  some  trouble  to  collect 
data  on  the  subject.  These  data  are  given  in  the  following  table, 
which  contains  results  obtained  by  Koettstorfer  (K),  F.  W.  and  A.  F. 
Stoddart  (S),  L.  Archbutt  (LA),  E.  Valenta  (V),  R.  Moore  (M), 
Hiibl  (HI),  O.  Hehner  (H),  W.  H.  Deering  (D),  the  author  (A),  and 
others.  In  many  instances  the  figures  are  the  average  or  extreme 
results  yielded  by  the  examination  of  a  large  number  of  samples,  the 
determinations  made  in  my  own  laboratory  numbering  many  hundreds. 
Still,  a  further  experience  will  doubtless  show  that  the  limits  stated 
in  the  table  in  many  instances  require  modification. 
The  table  gives,  in  most  cases,  the  number  of  samples  on  which  the 
figures  are  based,  together  with  the  percentage  of  caustic  potash 
required  for  saponification,  and  the  "saponification-equivalent"  corre- 
sponding thereto.  This  last  value  is  found  by  dividing  the  percentage 
of  KHO  required  to  saponify  the  oil  into  ,  56 10.  It  represents  the 
number  of  grammes  of  an  oil  which  would  be  saponified  by  one  liter 
of  a  normal  solution  of  any  alkali.  In  the  case  of  the  glycerides,  the 
saponification-equivalent  is  one-third  of  the  molecular  weight,  but  in 
the  case  of  monatomic  ethers,  like  those  which  essentially  constitute 
sperm  oil  and  beeswax,  the  saponification-equivalent  is  identical  with 
the  molecular  weight. 
28 
