282     Chemical  Examination  of  Ipomcea  Purpurea.     { ^m 'j°nl'wmarm' 
from  the  so-called  purgic  acid,  a  product  of  the  alkaline  hydrolysis 
of  "  convolvulin"  by  treatment  with  dilute  sulphuric  acid.  As 
Hoehnel,  however,  did  not  record  the  melting  point  of  his  acid,  and 
the  amount  of  acid  obtained  by  us  having  been  too  small  to  permit 
of  the  preparation  of  the  derivatives  described  by  him,  it  is 
impossible  to  decide  whether  the  two  substances  are  identical. 
Guerin1  has  synthesized  a-hydroxylauric  acid,  the  melting  point 
of  which  is  stated  to  be  73-74°  C.  As  Guerin  had  prepared  an 
anilide  of  this  acid  (m.  p.  83 °  C),  a  little  of  the  corresponding 
derivative  was  made  from  the  acid  obtained  by  us  for  the  purpose 
of  comparison,  the  method  employed  having  been  precisely  the 
same  as  that  adopted  by  Guerin.  A  product  was  obtained  in  the 
form  of  small,  lustrous  plates,  which  melted  at  15  5-1570  C.  It  is, 
therefore,  evident  that  the  hydroxylauric  acid  obtained  from 
Ipomoea  purpurea  is  not  the  alpha  compound. 
An  attempt  was  made  to  obtain  an  acetyl  derivative  of  the  above- 
described  acid,  but  the  product  was  an  oil,  which  did  not  solidify. 
(b)  Ether  Extract. — This  constituted  the  remainder  of  the  solid 
product  obtained  from  the  alcohol  extract  of  the  hydrolyzed  resin. 
After  purification  it  was  found  to  consist  entirely  of  ipurolic  acid, 
C14H2804,  which  had  previously  been  obtained  by  the  treatment  of 
the  alcohol  extract  of  the  original  resin  with  dilute  sulphuric  acid. 
On  analysis  it  gave  the  following  result : 
0-2228  gave  0  5280  C02  and  0-2146  H20.  C  —  64-6;  H  =  107. 
C14H2804  requires  C  =  64-6 ;  H  =  10  8  per  cent. 
The  acid  liquid,  from  which  the  above-mentioned  crystalline  acids 
had  been  separated,  was  treated  with  baryta  for  the  removal  of  the 
sulphuric  acid,  and,  after  filtration,  diluted  to  the  measure  of  I  litre. 
This  liquid  readily  reduced  Fehling's  solution  on  heating,  and 
yielded  an  osazone  which,  after  crystallization  from  pyridine,  melted 
at  212-2130  C,  and  was  therefore  ^-phenylglucosazone.  A  quanti- 
tative determination,  by  means  of  Fehling's  solution,  of  the  amount 
of  sugar,  formed  by  the  action  of  dilute  sulphuric  acid  on  the  alco- 
hol extract  of  the  hydrolyzed  resin,  indicated  that  25  grammes  of 
the  latter  had  yielded  4-3  grammes  of  glucose.  If  the  amount  of 
crystalline  acid   (5-5  grammes),  consisting  essentially  of  ipurolic 
1  Bull.  Soc.  chim.,  1903  [3],  29,  1124-1128,  and  Journ.  Chem.  Soc,  1904,  86, 
Part  I,  p.  138. 
