n6  Standardization  of  Preparations.      { Am^{rchJmTm' 
tonic  or  stimulant,  followed  by  a  pronounced  diuretic  effect,  as  was 
brought  out  in  the  first  portion  of  the  paper.  Assuming  Kiliani's 
work  to  be  the  most  nearly  correct,  we  have  present  in  digitalis 
leaves  three  principal  glucosides — digitoxin,  digitalin,  and  digitonin. 
Digitoxin  is  a  crystalline  glucoside,  soluble  in  alcohol  and  chloroform 
and  in  a  mixture  of  alcohol,  glycerin  and  water,  slightly  soluble  in 
ether  and  insoluble  in  water  and  petroleum  benzine ;  digitalin  is  an 
amorphous  glucoside,  soluble  in  alcohol  and  in  a  mixture  of  alcohol 
and  chloroform,  but  only  sparingly  soluble  in  ether,  chloroform  and 
water  ;  while  digitonin  is  a  crystallizable  glucoside,  soluble  in  alcohol 
and  in  a  mixture  of  alcohol  and  chloroform,  but  sparingly  soluble  in 
chloroform  alone,  and  differing  from  the  other  glucosides  in  being 
somewhat  more  soluble  in  water.  Moreover,  this  glucoside  renders 
digitalin  and  possibly  also  digitoxin  more  soluble  in  water — this  effect 
being  retroactive  on  the  digitonin,  increasing  its  water  solubility.  This 
effect  is  probably  further  increased  by  other  constituents  of  the  leaves 
such  as  saponins.  It  is  in  this  way  that  the  activity  of  an  infusion 
of  good  digitalis  leaves  is  accounted  for.  In  this  connection  I  wish 
merely  to  mention  some  experiments  in  which  we  attempted  to 
prepare  a  permanent  aqueous  solution  of  the  digitalis  glucosides 
directly  from  the  drug,  depending  upon  the  permanence  of  this 
mutually  reactive,  increased  water-solubility  effect.  They  were  un- 
successful, however,  since,  although  fully  active  at  first,  they  gradu- 
ally deteriorated,  until,  after  two  or  three  months,  scarcely  a  trace 
of  heart-stimulating  principles  remained  in  solution.  It  is  apparent, 
therefore,  that  only  hydro. alcoholic  preparations,  or  those  in  which 
part  of  the  alcohol  has  been  replaced  by  glycerin,  will  be  practically 
permanent. 
Of  these  three  glucosides  digitonin  is  present  in  greatest  amount, 
but  is  devoid  of  all  heart-stimulating  action.  Digitoxin  is  present 
in  next  to  largest  amount,  while  true  digitalin  comes  last.  Digi- 
toxin is  the  substance  which  is  by  far  the  strongest  heart-stimulating 
principle  in  the  drug,  although  the  true  amorphous  digitalin  also 
possesses  the  heart-stimulating  action  to  a  marked  degree. 
Much  of  the  confusion  of  prevalent  ideas  about  the  relative 
activity  of  the  digitalis  glucosides  is  due  to  the  unfortunate  jumble 
of  names  applied  to  them.  Thus,  commercial  German  digitalin,  of 
variable  activity,  is  composed  principally  of  digitonin,  while  crystal- 
lized French  digitalin  is  probably  identical  with  digitoxin. 
