AmsllZ'£^Tm'}  Saponification-Equiualents  of  Fixed  Oils.  435 
On  inspecting  the  results  recorded  in  the  foregoing  table,  it  appears 
that  the  oils  of  Group  A,  consisting  of  olein  with  comparatively  little 
stearin  or  palrnitin,  neutralize  appreciably  equal  quantities  of  potash, 
and  that  whether  of  animal  (like  lard  oil)  or  vegetable  origin  (e.  g., 
olive  and  almond  oils).  On  the  other  hand,  the  oils  of  Group  B,  all 
of  which  are  derived  from  cruciferous  plants,  neutralize  sensibly  less 
alkali  than  those  of  Group  A,  a  fact  which  is  explained  by  the 
presence  of  a  considerable  proportion  of  brassic  acid,  or  other  higher 
homologues  of  oleic  acid,  in  rape  oil  and  its  allies.  In  the  case  of  the 
drying  oils,  the  saponification-equivalents  are  not  characteristic,  but 
they  point  to  the  probability  of  linoleic  acid  having  a  higher  atomic 
weight  than  that  commonly  attributed  to  it.  This  suggestion  receives 
support  from  a  variety  of  facts  which  have  passed  under  my  notice, 
and  I  hope  to  refer  to  it  more  at  length  on  a  future  occasion.  The 
marine  animal  oils,  Group  D,  do  not  yield  very  characteristic  results, 
except  in  contrast  with  the  figures  of  Group  G,  the  oils  of  which 
are  not  glycerides,  but  consist  essentially  of  ethers  of  monatomic 
alcohols.  Porpoise  oil  is  remarkable  for  the  notable  proportion  of 
valerin  contained  in  it,  and  hence  for  its  comparatively  high  neutral- 
izing power.  Valeric  acid  is  also  the  characteristic  volatile  fatty  acid 
of  the  butter  from  porpoise  milk.  The  glyceride  of  valeric  acid  also 
exists  to  a  considerable  extent  in  whale  oil,  blackfish  oil,  and  dolphin 
oil.  Chevreul  obtained  from  the  last  named  oil  as  much  as  20*9  per 
cent,  of  valeric  acid. 
Of  the  solid  fats,  those  of  Group  E  resemble  porpoise  oil  in  containing 
glycerides  of  lower  fatty  acids,  and  hence  possess  lower  saponification- 
equivalents  than  the  oils  of  Group  F,  which  consist  essentially  of 
variable  mixtures  of  palmitin,  stearin,  and  olein.  Japan  wax  also 
contains  a  notable  proportion  of  lower  fatty  acids.  A  sample  exam- 
ined by  Hehner's  butter  method  gave  8  8 '4  per  cent,  of  insoluble  acids 
and  8 '4  per  cent,  of  soluble  acids,  calculated  as  C8  H16  02. 
The  saponification-equivalent  of  rape  oil  is  very  sensiby  reduced  by 
oxidation  or  "  blowing,"  a  fact  which  is  probably  due  to  the  formation 
of  lower  fatty  acids,  but  the  changes  produced  in  oils  by  oxidation 
much  need  further  investigation  by  the  aid  of  recent  methods  of 
analysis. — The  Analyst,  1886,  p.  145. 
Caffeine  in  hypodermic  injections  of  £  or  J  grain  has  been  found  by  Dr. 
Castle  ( Cine.  Lancet  and  Clinic)  to  successfully  relieve  neuralgia. 
