Am.  Jour.  Pharm. 
Sept.,  1887. 
Chemistry  of  Strophanthin. 
457 
whether  in  well-defined  crystals  or  not,  was  resolvable  by  acetate  of 
lead  into  at  least  two  bodies,  one  of  which  is  an  extremely  active  glu- 
coside,  and  the  other  an  acid  for  which  the  name  Jcombic  acid  is 
suggested.  It  being  apparent,  therefore,  that  the  strophanthin  first 
described  is  not  a  simple  substance,  attempts  were  made  to  improve 
the  process  so  as  to  separate  strophanthin  in  its  pure  state.  The  fol- 
lowing is  the  process  ultimately  adopted.  Starting  with  the  product 
obtained  in  the  earlier  process,  it  is  dissolved  in  water,  tannic  acid  is 
added,  and  the  tannate  digested  with  recently  precipitated  oxide  of 
lead.  Rectified  and  proof  spirit  are  now  used  to  extract,  and  the  ex- 
tract obtained  is  dissolved  in  a  small  quantity  of  rectified  spirit,  and 
the  solution  precipitated  by  ether.  The  precipitate  is  finally  dissolved 
in  weak  alcohol,  and  through  this  solution  carbonic  anhydride  is 
passed  for  several  hours,  by  which  means  lead  is  completely  got  rid 
of.  After  filtration  the  solution  is  evaporated  at  a  low  temperature 
and  dried  in  vacuo  over  sulphuric  acid. 
g  Strophanthin  thus  obtained  is  imperfectly  crystallized,  neutral  in 
reaction,  intensely  bitter,  freely  soluble  in  water,  less  so  in  rectified 
spirit,  and  nearly  insoluble  in  ether  and  chloroform.  It  burns  with- 
out residue,  and  contains  no  nitrogen.  The  percentage  composition 
from  the  average  of  several  closely  agreeing  results  was  found  to  be — 
C=55-97,  H=775,  0=36-28, 
which  agrees  fairly  with  the  formula  C20H3^O10. 
Strong  sulphuric  acid  produces  with  strophanthin  a  bright  green 
color,  which  soon  becomes  greenish-yellow  and  brown.  Sulphuric 
acid  and  potassic  bichromate  give  a  blue  color  in  addition  to  the  color- 
ation caused  by  the  acid  alone.  Phosphomolybdic  acid  produces  a 
bluish-green  color,  which  on  addition  of  water  becomes  pure  blue. 
With  a  1  per  cent,  solution  in  water,  phosphomolybdic  acid  causes 
slowly  a  bright  bluish-green  color.  Tannic  acid  produces  an  abundant 
white  precipitate,  soluble  both  in  excess  of  the  acid  and  of  strophan- 
thin. The  solution  is  not  changed  in  appearance  by  acetate  or  sub- 
acetate  of  lead,  platinic  chloride,  ferric  chloride  or  mercuric  chloride. 
Nearly  all  acid  reagents  cause  the  solution  to  become  hazy,  and  it  is 
then  found  that  the  solution  contains  glucose.  This  decomposition  is 
also  produced  by  sulphuretted  hydrogen,  especially  in  the  heat,  and 
for  this  reason  it  is  not  advisable  to  use  sulphuretted  hydrogen  in  any 
process  for  preparing  strophanthin. 
Indeed,  all  the  mineral  acids,  except  carbonic,  and  many  of  the 
