254     Chemical  Examination  of  Ipomcea  Purpurea.  {Amjine?iS)8arm' 
In  order  to  determine  the  value  of  this  factor  in  connection  with 
the  resin  under  investigation,  the  method  suggested  by  Guigues  was 
employed.  About  2-5  grammes  of  the  crude  resin  were  dissolved 
in  50  c.c.  of  alcohol,  and  the  solution  boiled  with  successive  small 
portions  of  animal  charcoal  until  it  became  practically  colorless. 
The  rotation  of  this  liquid  was  then  observed  in  a  1  dcm.  tube, 
after  which  10  c.c.  of  the  liquid  were  evaporated  to  dryness,  the  resi- 
due dried  at  105  — uo°  C,  and  weighed.  The  initial  rotation  in  a 
I  dcm.  tube  having  been  found  to  be  — 42',  and  as  the  amount  of 
solid  substance  in  10  c.c.  of  the  liquid  was  0-1374  gramme,  the 
specific  rotatory  power  of  the  resin  is  [a]D  —  50*95°. 
Preliminary  Extraction  of  the  Crude  Resin  with  Different  Solvents. 
In  order  to  ascertain  the  general  character  of  the  crude  resin,  an 
amount  of  the  latter  obtained  from  100  grammes  of  the  drug  (4  8 
grammes)  was  dissolved  in  alcohol,  mixed  with  purified  sawdust, 
and  the  thoroughly  dried  mixture  extracted  successively  in  a  Soxhlet 
apparatus  with  various  solvents.  The  percentages  of  extract,  dried 
at  no°  C,  were  as  follows : 
Per  cent. 
Petroleum  (b.  p.  40-600  C.)  extracted   8.0 
Ether                                    "    7-3 
Chloroform                            "    9*8 
Ethyl  acetate                         "         .  .  .   23-8 
Alcohol                                  "    490 
Loss   21 
IOO'O 
For  the  further  complete  examination  of  the  drug  a  quantity 
(43/4  Pounds  =  I9'6  kilograms)  of  the  ground  material  was  com- 
pletely extracted  with  hot  alcohol.  The  extract  thus  obtained,  after 
the  removal  of  the  greater  portion  of  the  alcohol,  was  brought  into 
a  large  flask,  some  water  added,  and  the  mixture  distilled  in  steam 
until  volatile  products  ceased  to  pass  over.  A  turbid  distillate  was 
thus  obtained,  from  which  a  few  oily  drops  separated  on  the  surface. 
After  this  operation  there  remained  in  the  distilling  vessel  a  dark- 
colored,  aqueous  liquid  (A),  which  possessed  an  agreeable,  fruity 
©dor,  and  a  quantity  of  soft,  very  dark  greenish  resin  (B),  which 
was  thoroughly  washed  with  warm  water  and  the  washings  added 
to  the  aqueous  liquid. 
