ON  THE  CONSTITUTION  OE  DIGITALIN. 
71 
i^igitalin  C^,  H,,       )  _  ^    tt  ^ 
Water   H,  0^  ^  — 
Subtract  2  atoms  of  glucose         C^^  O24 
1  atom  of  digitaliretin        Cg^  O^g 
Action  of  Caustic  Soda  on  Digitalin. — The  author  next 
studied  the  action  of  a  caustic  alkali  on  digitalin.  This  prin- 
ciple could  only  be  dissolved  in  a  moderately  concentrated  solu- 
tion of  caustic  soda  by  prolonged  ebullition.  The  solution,  when 
effected,  had  no  action  on  potassio-tartrate  of  copper ;  no  glu- 
cose, therefore,  had  been  formed.  Sulphuric  or  acetic  acid 
was  then  added,  and  to  the  alkaline  solution  a  flocculent  pre- 
cipitate obtained.  This  precipitate  was  dissolved  in  boiling 
alcohol,  the  solution  filtered  and  evaporated  to  a  syrupy  consist- 
ence, when  a  white  crystalline  mass  was  obtained,  having  a 
piquant  and  slightly  bitter  taste,  and  an  acid  reaction  on  litmus. 
It  consisted  of  a  new  acid,  which  the  author  has  named  digita- 
linic  acid.  The  crystals  of  this  acid,  examined  under  the 
microscope,  were  found  to  be  brilliant,  translucid,  micaceous 
scales.  This  acid,  when  treated  with  dilute  sulphuric  acid, 
immediately  underwent  the  same  decomposition  as  the  digitalin  ; 
it  was  split  up  into  glucose  and  digitaliretin. 
Pure  digitalinate  of  soda  was  prepared  by  boiling  digitalin 
with  a  considerable  excess  of  a  strong  solution  of  caustic  soda 
for  half  an  hour  or  more.  A  crystalline  pellicle  formed  on  the 
surface  during  ebullition.  The  solution  was  afterwards  nearly 
neutralized  with  sulphuric  acid,  leaving  it,  however,  slightly 
alkaline,  so  as  to  avoid  the  decomposing  action  of  the  acid  on 
the  digitalinic  acid.  The  liquid  was  then  evaporated  to  dryness, 
and  the  residue  boiled  with  spirit,  filtered,  and  the  solution 
allowed  to  crystallize.  A  second  crystallization  furnished  the 
salt  in  a  state  of  purity. 
These  two  decompositions  of  digitalin,  the  one  into  glucose 
and  digitaliretin  under  the  influence  of  a  dilute  acid,  the  other 
into  digitalinic  acid  by  the  action  of  a  strong  alkali,  show  the 
great  necessity  for  caution  in  the  process  adopted  for  its  pre- 
paration and  purification. — Lond.  Pharm.  Journ,  Sept,  1860, 
from  Journ.  de  Pharm, 
