284     Chemical  Examination  of  Ip omasa  Purpurea.     {  ^mjinUe?i9osfrm> 
by  distillation  with  steam,  there  remained  in  the  distillation  flask  a 
dark-colored  aqueous  liquid  and  a  quantity  of  a  soft  resin.  The 
aqueous  liquid  contained  a  considerable  quantity  of  potassium 
chloride  and  nitrate,  together  with  tannic  and  coloring  matters,  and 
yielded  glucose  on  heating  with  a  dilute  mineral  acid. 
The  most  important  product  yielded  by  Ipomcea  purpurea  is  the 
above-mentioned  resin,  the  amount  of  which  corresponded  to  4-8 
per  cent,  of  the  weight  of  the  drug,  and  of  this  resin  15-5  per  cent, 
was  soluble  in  ether.  The  crude  resin,  which,  when  dry,  can  be 
reduced  to  a  dark  brown  powder,  is,  however,  an  exceedingly  com- 
plex mixture,  as  has  been  shown  by  the  results  of  its  successive 
extraction  with  the  following  solvents :  (I)  light  petroleum,  (II) 
ether,  (III)  chloroform,  (IV)  ethyl  acetate,  and  (V)  alcohol.  The 
examination  of  these  various  extracts  has,  moreover,  rendered  it 
evident  that  each  of  them  is  likewise  of  complex  composition. 
The  crude  resin  is  optically  active.  After  treatment  with  animal 
charcoal  to  deprive  it  of  coloring  matter,  it  was  found  to  have  a 
specific  rotatory  power,  in  alcoholic  solution,  of  [a]D  —  50*95  °. 
The  products  obtained  from  the  various  extracts  of  the  resin  were 
as  follows : 
I.  Petroleum  Extract. — This  represented  8  per  cent,  of  the  total 
resin.  After  treatment  with  an  alcoholic  solution  of  potassium 
hydroxide,  it  yielded  pentatriacontane,  C35H72  (m.  p.  74-/5°  C.) ;  a 
phytosterol,  C27H460,  H20  (m.  p.  132-I33°C;  [a]D —  32-1°);  formic, 
butyric,  and  higher  volatile  acids;  stearic,  and  apparently  some  pal. 
mitic  acid,  with  a  very  small  amount  of  an  unsaturated  oily  acid. 
II.  Ether  Extract. — This  represented  7-3  per  cent,  of  the  total 
resin.  When  fused  with  potassium  hydroxide  it  yielded  formic  and 
butyric  acids,  a  mixture  of  higher  volatile  acids,  and  a  very  small 
amount  of  a  crystalline  acid,  melting  at  103-1040  C,  which  was 
apparently  azelaic  acid,  C9H1604,  together  with  a  trace  of  substance 
giving  the  catechol  reaction.  The  extract,  when  heated  with  5  per 
cent,  alcoholic  sulphuric  acid,  yielded,  besides  a  quantity  of  resin,  a 
small  amount  of  a  neutral  oil,  having  a  pleasant  odor,  together  with 
formic,  butyric  and  higher  volatile  acids,  a  readily  soluble  non-vola- 
tile acid,  and  glucose. 
III.  Chloroform  Extract. — This  represented  9-8  per  cent,  of  the 
total  resin.  When  fused  with  potassium  hydroxide,  it  yielded  pro- 
ducts analogous  to  those  obtained  under  the  same  conditions  from 
