Am  J^y-1^arm-}  Action  of  Sulphuric  Acid  on  Oleic  Acid.  351 
partly  of  a  liquid ;  the  former  being  more  sparingly  soluble  in  ether 
was  freed  from  the  latter  by  washing  with  this  solvent.  This  solid 
substance  evidently  consists  of  a  fatty  acid;  it  melts  after  repeated 
crystallization  at  79°  ;  the  analytical  data  point  to  its  being  hydroxy- 
stearic  acid,  a  view  confirmed  by  determinations  of  the  degree  of 
saturation  of  the  compound  by  means  of  HiibPs  method  (described 
in  1884),  the  hydroxystearic  acid  was  converted  into  iodostearic  acid 
(identical  with  SaytzefFs  compound,  described  in  1885,)  and  into 
stearic  acid.  The  melting  point  of  hydroxystearic  acid,  as  determined 
by  the  author,  differs  somewhat  from  the  data  of  former  investigators 
(varying  from  56°  to  85*5 °). 
The  liquid  substance,  after  repeated  washing  with  alcohol,  gives  a 
liquid  residue  which  seems  to  be  the  anhydride  of  hydroxystearic 
acid;  it  is  also  obtained  by  heating  the  acid  at  130-150°.  It  does 
not  combine  with  bases,  is  sparingly  soluble  in  alcohol,  and  is  con- 
verted into  the  acid  by  boiling  with  alkalis ;  an  attempt  to  convert  the 
anhydride  into  the  corresponding  amide  failed.  The  substance 
extracted  by  alcohol  from  the  liquid  portion  contains  in  addition 
to  a  certain  quantity  of  this  anhydride  and  of  hydroxystearic  acid, 
an  unsaturated  liquid  fatty  acid,  which  seems  to  be  unaltered  oleic 
acid. 
The  portion  of  the  product  soluble  in  water  was  found  to  consist 
of  sulphohydroxystearic  acid,  as  proved  by  analysis  of  its  copper 
salt,  and  by  determination  of  its  degree  of  saturation  by  HiibPs 
method.  This  sulphonic  acid  is  easily  decomposed,  especially  by 
heating  it  on  the  water-bath  with  hydrochloric  acid,  into  hydroxy- 
stearic  and  sulphuric  acids.  Its  aqueous  solution  always  retains  a 
certain  amount  of  oleic  and  hydroxystearic  acids  and  the  anhydride  of 
the  latter. 
On  the  whole,  the  experiments  show  that  the  duration  of  the  reac- 
tion between  oleic  and  sulphuric  acid  does  not  influence  the  quantity 
of  sulphonic  acid  formed,  20  per  cent,  of  the  oleic  acid  being  obtained 
as  a  rule  in  the  form  of  this  compound:  7*5-15  per  cent,  remain 
unchanged,  and  70  per  cent,  is  converted  into  hydroxystearic  acid 
and  its  anhydride.  These  data,  as  well  as  the  non-formation  of 
sulphurous  anhydride,  do  not  agree  with  the  explanations  of  this 
reaction,  proposed  by  former  investigators  (Midler-Jacobs,  Liechti  and 
Suida,  LukianofF) ;  the  author  considers  it  most  probable  that  the 
action  of  sulphuric  acid  on  oleic  acid  consists  of  a  series  of  simul- 
