434 
Asclepias  Cornuti. 
f  Am.  Jour  Pharm. 
t      Sept.,  1881. 
iridescent  in  the  sunliglit,  volatilized  at  a  low  heat,  leaving  no  residue, 
have  no  reaction  on  litnuis  paper,  are  very  soluble  in  chloroform,  sol- 
uble in  benzin,  ether  and  alcohol,  insoluble  in  water.  In  contact  with 
strong  sulphuric  acid  and  bichromate  of  potassium  they  give  a  green 
color.  With  strong  sulphuric  acid  and  chlorinated  lime  they  give  at 
first  a  brown  color,  but  on  standing  a  short  time  this  turns  to  a  purple. 
2 
Asclepias  Cornuti.— 1,  Portion  of  rhizome.  2,  Transverse  section, 
natural  size.  3,  Transverse  section,  magnified.  4,  Bast  fibre. 
5,  Lactieiferous  vessel,    G,  Starch  granules. 
These  crystals  may  also  be  obtained  by  exhausting  the  sticky  benzin 
extract  with  ether,  but  on  account  of  the  fatty  matter  which  ether 
takes  up  it  is  difficult  to  obtain  them  pure.  Another,  and  probably 
the  best  method,  is  to  percolate  the  drug  directly  with  alcohol,  concen- 
trating the  tincture  and  setting  aside  that  crystals  may  form.  The 
vellow  crystals  thus  obtained  are  best  purified  by  dissolving  in  a  mix- 
ture of  chloroform  and  alcohol,  shaking  with  animal  charcoal,  filtering 
and  setting  aside  for  spontaneous  evaporation,  washing  with  diluted 
alcohol  and  drying  in  a  cool  place.  In  all  three  of  the  above  methods 
it  is  important  that  the  least  possible  amount  of  heat  should  be  used. 
The  benzin  extract,  after  having  been  exhausted  Avith  alcohol,  ether, 
water  and  dilute  hydrochloric  acid,  consists  of  a  yellow,  sticky  tena- 
cious substance,  readily  soluble  in  carbon  bisulphide,  chloroform  and 
