194  AN  ESSAY  ON  SENNA. 
i 
beridacese,  Menispermacese  and  Anonaceae.  But  on  examining 
and  comparing  the  relationship  of  these  orders,  we  will  find  them 
to  possess  many  marked  points  of  resemblance,  indicating  their 
close  alliance  in  natural  classification,  which,  indeed,  warrants 
their  consecutive  arrangement  in  botanical  works.  But  to  bring 
the  natural  orders  "  Polygonacese  "  and  "Leguminosse  "  together, 
for  points  of  resemblance  even  in  outward  characters,  is  beyond 
reasonable  possibility.  From  such  a  train  of  reasoning  we  have 
therefore  the  greatest  reason  to  doubt  the  fact  of  the  existence 
of  chrysophanic  acid  as  the  purgative  principle  in  Senna ;  and 
it  was  the  purpose  of  the  writer  of  this  paper  to  direct  the  course 
of  his  experiments  primarily  to  prove  whether  this  principle  was 
to  be  found  in  the  drug.  The  first  experiment  made  was 
founded  on  the  well  known  fact,  that  the  purely  alcoholic  tinc- 
ture of  the  leaves  possessed  no  purgative  properties. 
Exp.  I.  Two  ounces  of  Alexandria  Senna,  freed  from  stems 
and  legumes,  were  powdered  and  treated  in  a  displacer  with 
stronger  alcohol,  until  the  menstruum  passed  through  colorless. 
The  resulting  tincture  was  of  a  deep  olive  brown  color,  and  pos- 
sessed a  nauseous,  bitter  taste.  It  was  evaporated  to  a  small 
bulk  of  syrupy  extract  and  thrown  into  a  pint  of  water.  There 
was  deposited  an  insoluble,  brown  resin,  while  the  water  remained 
green  and  turbid,  even  after  several  filtrations. 
The  precipitated  resin  had  an  acrid,  bitter  taste,  and  was 
readily  soluble  in  alcohol.  Its  solution,  agitated  with  animal 
charcoal,  filtered  and  evaporated,  left  the  resin  of  a  much  lighter 
color,  but  having  the  same  nauseous  odor  and  taste.  It  was 
readily  soluble  in  a  solution  of  caustic  soda,  from  which  it  was 
precipitated,  evidently  unchanged  by  the  addition  of  any  of  the 
stronger  acids.  It  was  partaken  of  in  several  doses  of  five  grains, 
each  dose  being  equivalent  to  gi.  of  the  drug,  but  produced  no 
purgative  effect  whatever. 
The  powder  remaining  in  the  percolator,  after  its  exhaustion 
by  alcohol,  was  acted  on  by  cold  water.  The  resulting  infusion 
was  of  a  deep  brown  color,  perfectly  transparent,  and  differed 
from  a  common  infusion  in  not  having  so  intensely  nauseous 
a  taste.  Salt  of  the  peroxide  of  iron  produced  a  greenish  black 
color,  rendered  lighter  by  slight  ebullition,  while  gelatine  gave 
