410 
ON  CROTON  OIL. 
strata  in  the  receiver.  The  lower,  oily  one  consisted  of  14  parts 
of  oil  and  1  part  of  alcohol;  the  upper,  which  was  thinly  fluid, 
was  composed  of  23  parts  of  alcohol  and  1  part  of  oil. 
The  seeds  were  pressed  while  still  soaked  with  alcohol,  by 
which  means  a  considerable  further  quantity  of  oil  was  obtained; 
upon  this  a  stratum  of  alcohol  floated.  From  this  third  oil  and 
the  preceding  the  alcohol  was  distilled  away,  and  the  oil  was  then 
collected.    The  oil  is  thus  obtained  in  four  divisions  : — 
1.  That  pressed  with  the  aid  of  heat ; 
2.  That  displaced  by  alcohol  and  retained  in  solution ; 
3.  That  displaced  by  alcohol  and  not  dissolved,  but  obtained 
as  an  oily  stratum  below  the  preceding ; 
4.  That  expressed  from  the  residue  of  2. 
The  oils  obtained  by  the  different  treatments  of  the  seeds  were 
of  three  kinds  as  regards  their  inflammatory  action  upon  the  skin. 
The  most  efficacious  was  that  obtained  from  the  alcoholic  solu- 
tion ;  whilst  that  which  formed  the  thicker  stratum  below  this 
solution  was  far  less  active ;  but  the  oils  obtained  by  the  first 
and  second  pressure  were  far  inferior  even  to  this  in  acridity. 
The  fatty  oil  of  croton  oil,  when  saponified,  furnished  stearic 
acid,  C36H3604,  palmitic  acid,  C32H32  04,  myristic  acid,  C28H28 
O4,  and  lauric  acid,  C24  H24  O4 ;  of  the  oleic  acid  series  probably 
some  members  between  C20  H18  O4  and  C34  H18  O4 ;  and  besides 
these,  crotonic  acid  of  the  formula  C8  H6  O4  and  angelic  acid, 
C10  H8  O4.  All  these  acids  are  contained  as  glycerides  in  the 
fresh  oil. 
It  also  appears  from  the  author's  experiments,  that  the 
crotonic  acid  is  neither  the  caustic  nor  the  purgative  matter. 
The  caustic  matter  of  croton  oil  is  a  resinous  body,  crotonole^ 
the  formula  of  which  is  C18  H14  O4,  or  a  multiple  of  it. 
The  frequently  peculiar  odor  of  croton  oil,  which  has  the 
greatest  similarity  with  the  decoction  of  Senega  root,  is  due  to 
a  product  of  decomposition  of  the  crotonole.  Another  product 
of  its  decomposition  is  the  volatile  oil  of  previous  observers. 
The  caustic  matter  in  croton  oil,  crotonole,  has  no  purgative 
action.  The  latter  property  belongs  to  another  body  which  was 
not  detected. 
With  regard  to  crotonic  acid,  the  author  shows  particularly 
that  it  forms  a  member  of  the  oleic  series  lying  between  angelicic 
