70 
ON  THE  CONSTITUTION  OF  DIGITALIN. 
It  thus  became  evident  that  digitalin,  in  common  with  many 
other  substances,  is  a  copulated  body,  consisting  of  sugar  com- 
bined "with  a  new  principle,  for  which  the  author  proposes  the 
name  digitaliretin.  The  digitaliretin,  which  separated  as  a 
fiocculent  precipitate  during  the  boiling,  was  purified  by  dis- 
solving it  in  rectified  spirit,  filtering,  slightly  evaporating  the 
solution,  and  allowing  it  to  undergo  spontaneous  evaporation. 
A  deposit  took  place  after  some  hours,  and  ultimately  a  granular 
mass,  of  a  greyish- white  color,  was  obtained,  which  was  redis- 
solved  in  alcohol  and  again  allowed  to  deposit.  Brilliant  grains 
of  pure  digitaliretin  were  so  obtained. 
This  substance  is  almost  insoluble  in  water,  to  which,  however, 
it  imparts  a  slightly  bitter  taste.  It  is  only  slightly  soluble  in 
ether  and  rectified  spirit,  but  hot  spirit  dissolves  it  easily.  The 
solution  is  bitter,  although  much  less  so  than  digitalin.  It 
slightly  reddens  blue  litmus  paper.  It  is  insoluble  in  the  caus- 
tic alkalies.  Its  alcoholic  solution  is  scarcely  troubled  by  an 
alcoholic  solution  of  acetate  of  lead,  but  upon  evaporating  the 
mixture  a  granular  precipitate  is  produced,  the  liquid  at  the 
same  time  acquiring  an  acid  reaction.  By  neutralizing  this  acid 
with  ammonia,  a  copious  fiocculent  precipitate  is  formed,  which 
dissolves  on  boiling  and  reappears  on  cooling.  When  an  alco- 
holic solution  of  nitrate  of  silver  is  added  to  a  solution  of  di- 
gitaliretin, a  precipitate  slowly  forms,  composed  of  small  brilliant 
prisms  of  digitaliretate  of  silver,  which,  by  standing  for  some 
time,  become  brown,  and  on  the  application  of  heat  undergo 
decomposition,  with  the  deposition  of  metallic  silver  on  the  sides 
of  the  tube. 
The  author  submitted  both  digitalin  and  digitaliretin  to 
analysis.  The  composition  of  anhydrous  digitalin  accorded 
with  the  formula  C^^  H^^  Og^.  Hydrated  digitalin  contains 
eight  atoms  of  water  in  addition,  the  whole  of  which  are  driven 
off  at  100°  C.  Anhydrous  digitalin  is  very  hygroscopic,  and 
readily  attracts  the  above  amount  of  water  from  the  air.  The 
analysis  of  digitaliretin  gave  numbers  according  with  the  formula 
OiQ.  By  adding  four  equivalants  of  water  to  the  for- 
mula of  digitalin,  the  sum  of  two  equivalents  of  glucose  and 
one  of  digitaliretin  are  obtained  ;  the  decomposition  of  digita- 
linj  as  above  described,  is  therefore  readily  accounted  for. 
