SENNA. 
71 
During  the  process  a  dark-colored  resin  separated.  From  the 
strong  solution  a  little  rectified  spirit  precipitated  sulphate  of 
ammonia  and  other  salts,  and  then,  twice  its  volume  of  ether 
being  added,  a  dark-colored  sweet  extractive  was  thrown  down. 
The  filtrate,  after  evaporation,  etc.,  was  a  second  time  so  treated, 
and  a  second  crop  of  extractive  obtained. 
The  ether-spirituous  solution  shaken  mth.  water,  yielded  to  it 
a  bitter  substance  of  dark  color  and  not  unpleasant  flavor.  In 
doses  of  5  grains  it  had  no  effect  whatever  on  the  bowels.  The 
extractive  was  also  inoperative.  The  bitter  was  doubtless 
derived  from  the  Cjnanchum,  of  which  it  may  be  said  to  be  the 
active  principle. 
The  marc  from  which  the  spirituous  tincture  had  been  pressed 
was  now  exhausted  with  water,  and,  from  the  infusion,  purified 
from  the  senna  acids  by  acetate  of  lead,  the  glucoside  acid  was 
precipitated  with  diacetate  of  lead.  This  compound  having  been 
decomposed  with  sulphuretted  hydrogen  and  ammonia  added,  the 
glucoside  was  precipitated  in  combination  with  ammonia  by  rec- 
tified spirit.  It  remained  now  as  a  last  resource  to  try  its  medi- 
cinal effect ;  not  with  much  hope  of  result,  but  still  acknowledging 
the  possibility  of  this  tasteless  and  apparently  inert  substance 
being  so  modified  in  its  course  through  the  system  (bearing  in 
mind  also  that  senna  acts  only  indirectly  on  the  bowels),  as  to 
enable  it  to  produce  the  cathartic  effect  I  desired  to  experience. 
On  taking  a  dose  of  5  grains,  I  was  pleased  to  find  that  some 
disturbing  effect  was  produced.  A  repetition  of  the  experiment 
enabled  me  to  decide  that  the  glucoside  w^as  the  active  principle 
of  senna.  Flattering  myself  that  I  had  made  a  discovery  of 
something  not  hitherto  announced,  I  proceeded  to  prepare  the 
glucoside  by  precipitating  it  directly  from  a  concentrated  infu- 
sion of  senna,  in  combination  v^ith  the  bases — lime,  magnesia, 
add  potash,  with  which  it  is  naturally  associated.  I  found  that 
the  first  precipitate  was  much  contaminated  with  the  senna  acids 
in  combination  with  lime,  and  was  of  little  virtue ;  the  second 
precipitate  was  more  active,  and  of  this  4  grs.  acted  fairly  as  a 
purge. 
Just  at  this  time  I  became  aware  of  the  existence  of  the  paper 
on  senna  by  Dragendorff  and  Kubly.    It  was  pointed  out  to  me 
