SENNA. 
65 
SENNA. 
By  Thomas  B.  Groves,  F.C.S. 
What  I  have  to  say  about  this  interesting  article  of  Materia 
Medica  will  be  confined  to  its  chemical  history,  ancient  and  mo- 
dern, and  will  include  an  account  of  some  attempts  I  have  re- 
cently made  to  set  at  rest  disputes  as  to  the  nature  and  properties 
of  its  active  principle. 
A  comparison  of  the  statements  of  authors  of  repute  respect- 
ing this  active  principle  will  show  at  once  the  necessity  there 
existed  for  bestowing  further  labor  on  the  subject.  The  analyses 
given  by  Pereira  comprise  one  by  Braconnot  of  the  watery 
extract  of  Alexandrian  senna,  one  by  Lassaigne  and  Fenuelle 
of  senna  leaves,  and  one  by  Fenuelle  of  senna  legumes.  It  will 
be  sufficient  for  my  purpose  to  quote  parts  only  of  these  analyses. 
Thus  Braconnot  finds  in  104*2  pts.  of  watery  extract  of  Alexan- 
drian senna  53*7  pts.  of  the  bitter  matter  of  senna;  as  senna  is 
not  bitter  when  unmixed,  it  is  pretty  clear  that  Braconnot 
operated  on  a  sample  of  senna  containing  the  bitter  leaves  of 
CynancTium  Argel,  without  making  allowance  for  the  fact.  He 
mentions  also  31*9  per  cent,  of  reddish-brown  gum — a  most  in- 
definite term.  On  the  whole,  it  may  be  said  that  the  analysis  is 
perfectly  useless. 
Lassaigne  and  Fenuelle  give  a  qualitative  statement  only,  at 
the  head  of  which  figures  cathartin,  a  principle  (?)  found  also  in 
senna  legumes  by  Fenuelle.  This  substance  is  described  as  being 
yellowish-red,  uncrystallizable,  with  a  peculiar  odor  and  a  bitter 
nauseous  taste,  very  soluble  both  in  water  and  alcohol,  but  in- 
soluble in  ether.  Its  aqueous  solution  is  precipitated  by  infusion 
of  galls,  diacetate  of  lead,  etc.,  etc.  Three  grains  caused  nausea, 
griping  and  purging.  Its  preparation  is  thus  efiected.  To  a 
filtered  decoction  of  senna  add  acetate  of  lead,  filter,  remove  the 
excess  of  lead  with  sulphuretted  hydrogen,  filter  and  evaporate 
to  an  extract,  which  exhaust  with  rectified  spirit ;  again  evapor- 
ate to  an  extract,  add  a  little  sulphuric  acid  to  remove  potash, 
present  in-  combination  with  acetic  acid,  and  finally  purify  secun- 
dum artem  from  traces  of  lead  or  of  sulphuric  acid  if  necessary. 
This  substance,  which  I  need  scarcely  say  is  not  worthy  of  the 
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