28  Digitalis  Glucosides  and  Allied  Drugs.  {Ajaif^y  m™' 
from  the  lead,  precipitating  with  tannic  acid ;  the  combination  of 
gluocoside  and  tannin  thus  formed  was  decomposed  by  adding  lead 
oxide,  and  the  glucoside  thus  set  free  was  then  extracted  with 
alcohol.  After  the  evaporation  of  the  alcohol,  impure  digitalin 
remained,  this  was  then  freed  from  fat  by  means  of  ether,  rendered 
colorless  by  animal  charcoal  and  then  precipitated  from  alcohol. 
The  preparation  thus  obtained  consisted  of  both  amorphous 
and  crystalline  substances,  for  which  reason  the  digitalin  of  Homolle 
has  been  described  in  the  literature  sometimes  as  an  amorphous 
and  sometimes  as  a  crystalline  body.  The  French  pharmacopoeia  of 
1866  retained  the  method  of  preparing  digitalin  as  described  by 
Homolle ;  but  this  yielded  a  preparation  which  was  not  completely 
soluble  in  chloroform.  For  this  reason  the  pharmacopoeia  in  ques- 
tion required  that  the  digitalin  should  be  redissolved  in  chloroform 
and  the  latter  evaporated.  In  this  way  "  digitaline  chloroformique  " 
was  obtained  as  a  yellowish-brown,  amorphous  preparation,  com- 
pletely soluble  in  alcohol  and  in  chloroform. 
Digitalin  was  now  further  investigated  by  Homolle  in  con- 
junction with  Quevenne,  and  they  succeeded  in  isolating  three  diff- 
erent substances  from  digitalin.  By  treating  it  with  a  mixture 
of  alcohol  and  ether  of  specific  gravity  0.78,  these  authors  obtained 
an  insoluble  residue  and  a  solution.  The  former  they  named  "  le 
digitalin."  The  solution  in  alcohol  and  ether,  when  evaporated, 
left  a  residue  which  was  only  partially  soluble  in  alcohol  (50  p.  c). 
They  named  the  soluble  portion  "  la  digitaline,"  and  the  insoluble 
portion  "  digitalose." 
It  may  be  here  mentioned  that  Homolle's  further  researches, 
and  the  nomenclature  adopted  by  him,  already  introduced  a  con- 
siderable degree  of  confusion,  for  the  author  unfortunately  made  a 
distinction  between  digitalin  and  digitaline.  I  shall  therefore  in 
the  following  remarks  always  add  the  name  of  the  author,  when 
necessary,  in  order  to  avoid  errors. 
Two  years  after  Homolle's  first  publication  regarding  digitalin, 
Walz  began  his  reports  dealing  with  his  work  on  this  subject. 
He  first  prepared  an  alcoholic  extract  of  digitalis  leaves  and  pre- 
cipitated those  substances  which  were  soluble  in  water  (e.  g.,  its 
aqueous  extract)  with  tannic  acid.  When  decomposed  by  lead 
oxide  the  tannin  compound  thus  formed  constituted  the  raw 
digitalin  Walz.  According  to  Walz,  when  this  substance  is  treated 
with  ether,  fat  and  two  other  substances  dissolve;  the  author  named 
