Am.  Jour.  Pharm. 
July,  1887. 
Gleanings  in  Materia  Medica. 
347 
removed  by  alcohol.  Prof.  Kobert,  of  Dorpat,  reports  (Chemiker 
Zeit,  1887,  No.  28,  p.  416,)  the  results  of  researches  made  at  his  sug- 
gestion by  Ernst  von  Hirschheydt,  which  show  that  the  oil  contains 
Bucbheim's  crotonoleic  acid,  partly  in  the  free  state  and  partly  as  glyc- 
eride.  The  latter  is  not  poisonous,  but  the  free  acid  is  very  irritating 
and  drastic.  The  glyceride  being  decomposed  by  the  pancreatic  fer- 
ment, thereby  becomes  purgative  when  taken  internally  ;  but  the  same 
effect  may  be  produced  by  giving  crotonoleic  acid  in  pills  covered  with 
keratin  with  the  view  of  preventing  irritation  of  the  stomach  ;  but 
obviously,  irritation  of  the  intestines  will  be  produced  by  both  com- 
pounds. 
The  solubility  of  croton  oil  is  mainly  influenced  by  the  age  of  the 
oil,  and  samples  are  sometimes  met  with  which  dissolve  in  alcohol  in 
all  proportions ;  but  it  does  not  seem  necessary  that  such  oils  should 
contain  the  crotonoleic  acid  only  in  the  free  state,  though  the  acid  is 
readily  soluble  in  alcohol. 
For  the  preparation  of  crotonoleic  acid  Kobert  recommends  diges- 
tion in  a  water-bath  of  the  alcohol-soluble  portion  of  croton  oil  with 
an  excess  of  concentrated  baryta  solution  ;  the  thick  white  mass  is 
thoroughly  mixed  and  washed  with  cold  distilled  water,  whereby  col- 
oring matter  and  barium  acetate,  butyrate  and  tiglinate  are  removed ; 
the  residue  is  drained,  dried  and  exhausted  by  ether,  which  leaves  be- 
hind the  barium  salts  of  stearic,  palmitic  and  lauric  acids.  On  evap- 
orating the  ethereal  solution  a  mixture  of  barium  oleate  and  croton- 
oleate  is  obtained,  of  which  the  latter  only  is  dissolved  by  alcohol  j 
this  solution  is  decomposed  by  the  careful  addition  of  H2S04,  and 
after  filtering  evaporated.  The  main  difficulty  for  the  preparation  ot 
free  crotonoleic  acid  lies  in  the  readiness  of  its  being  decomposed  by 
baryta  water  under  the  influence  of  too  high  a  heat. 
Sodium  crotonoleate  alters  the  walls  of  the  blood  vessels  and  causes 
hemorrhages. 
Asclepias  currasavica,  A.  incarnata  and  Vincetoxicum  officinale  were 
found  by  C.  Gram  (Chem.  Centr.  1886,  p.  735)  to  contain  a  glucoside, 
asclepiadin  which  is  readily  soluble  in  water,  sparingly  soluble  in  alco- 
hol, and  is  easily  converted  into  the  less  active  asclepin.  Harnack's 
asclepiadin  which  appears  to  be  identical  with  Feneulle's  asclepin,  was 
obtained  from  the  herbaceous  portion  of  Ascl.  currasavica.  The  root 
of  vincetoxicum  yielded  asclepidin,  but  no  asclepin.  Of  two  com- 
mercial resinoids  of  Ascl.  tuberosa  that  prepared  by  Parke,  Davis  & 
