454  Digitonin  and  Digitogenin.  {AmsSt?i£iarln' 
per  cent,  alcohol  (4  parts)  at  50-60°  and  the  solution  allowed  to 
crystallize  slowly.  The  crude  product  thus  obtained  is  dissolved  in 
12  times  its  weight  of  boiling  alcohol  (85  per  cent.),  heated  for  two 
minutes  with  animal  charcoal,  and  filtered ;  by  rubbing  the  sides  of 
the  beaker  as  the  solution  cools,  the  product  is  obtained  in  nodular 
aggregates  of  slender  needles.  The  crystals  are,  however,  more 
compact  and  the  product  purer  if  the  solution  is  allowed  to  cool 
very  slowly  without  rubbing  the  sides  of  the  beaker.  Digitonin 
crystallizes  easily  from  85  per  cent,  alcohol,  whilst  from  stronger 
alcohol  it  is  only  obtained  in  the  amorphous  state,  begins  to  soften 
at  225 °,  is  completely  melted  at  235°,  and  is  laevo-rotatory ;  for  a  2-8 
per  cent,  solution  in  75  per  cent,  acetic  acid,  \_a\  =  — 50°.  The 
amorphous  digitonin  of  Schmiedeberg  dissolved  in  cold  water  in  all 
proportions;  the  crystalline  substance  is  sparingly  soluble  in  water; 
on  heating,  it  dissolves  more  easily,  but  does  not  crystallize  on 
cooling,  and  the  solution  always  shows  an  opalescence.  With  con- 
centrated sulphuric  acid,  it  gives  a  red  solution ;  the  addition  of  a 
drop  of  bromine-water  greatly  intensifies  the  reaction.  Concen- 
trated hydrochloric  acid  gives  a  colorless  solution  which,  after  a 
time  or  on  heating,  turns  yellow  and  then  red.  Heated  with  dilute 
hydrochloric  acid  under  the  same  conditions  as  were  before  given 
for  digitalin,  it  yields  nearly  the  calculated  quantities  of  digitogenin, 
dextrose  and  galactose.  The  digitogenin  obtained  in  this  way  was 
identical  in  every  respect  with  that  formerly  obtained  from  digi- 
talin. 
Derivatives  of  Digitogenin. — When  digitogenin  is  heated  in  a 
sealed  tube  with  concentrated  hydriodic  acid  and  red  phosphorus,  a 
large  quantity  of  a  resin  containing  iodine  is  formed ;  but  neither 
methyl  nor  ethyl  iodide. 
Acetyldigitogenin,  C^H^OgAc,  is  obtained  by  heating  digitogenin 
(1  part)  with  anhydrous  sodium  acetate  (1  part)  and  acetic  anhydride 
(6  parts)  in  a  reflux  apparatus  for  one  hour,  and  pouring  the  bright 
red  solution  in  a  fine  stream  into  a  large  quantity  of  water.  It 
crystallizes  from  a  small  quantity  of  absolute  alcohol  in  beautiful 
needles,  melts  at  1780,  and  is  extremely  soluble  in  warm  alcohol, 
ether  and  acetic  acid.  Instead  of  sodium  acetate,  sulphuric  acid  can 
be  employed  as  a  condensing  agent ;  when  zinc  chloride  is  employed, 
amorphous  compounds  which  were  not  examined  are  obtained.  The 
author  points  out  that  the  formation  of  a  monacetyi  derivative  from 
