^"''Ma^'iSi'''^"''}        Active  Pr'mciple  of  Senna  Leaves.  259 
minous  substances.  He  describes  the  acid  as  shiny  bhick  in  color  and 
non-crystalline,  insoluble  in  ether,  absolute  alcohol  and  water,  but 
soluble  in  dilute  alcohol.  He  assigns  to  it  the  formula  Cj8oH950g2N2S, 
and  shows  that  it  is  a  glucoside,  being  easily  split  up  into  glucose  and 
a  body  which  he  names  cathartogenic  acid.  In  addition  he  gives  some 
experiments  to  show  that  it  is  a  colloid  and  diffuses  with  great  diffi- 
culty through  animal  membranes. 
Rau^  obtained  a  crystalline  body  which  he  named  sennin,  but 
Kubly^  has  since  shown  that  it  consists  simply  of  sulphur  and  a  bitter 
stuff. 
More  lately  Bourgoin  and  Bouchut^  have  stated  that  in  the  leaves 
there  are  three  purgative  bodies — chrysophanic  acid,  cathartic  acid 
and  another  unnamed  substance.  They  do  not  appear,  however,  to 
have  tested  the  physiological  action  of  the  bodies  which  they  sepa- 
rated. 
The  above  is  as  brief  an  account  as  possible  of  all  the  literature  on 
the  subject  which  I  have  been  able  to  find.  The  results  of  Kubly  are 
those  which  are  to  be  found  in  most  of  the  standard  text-books  of  the 
present  day,  but  the  formula  which  he  has  assigned  to  cathartic  acid 
rouses  the  suspicion  that  he  was  not  dealing  with  a  pure  body  but 
with  a  mixture.  This  idea,  coupled  with  a  desire  to  investigate  more 
fully  the  action  of  senna  as  a  purgative,  led  me  to  undertake  a  further 
investigation  of  the  subject. 
In  my  first  attempts  to  isolate  the  acid  I  used  as  precipitants  various 
salts  of  lead,  lime,  copper  and  soda,  but  invariably  obtained  by  these 
methods  a  substance,  which  although  strongly  purgative  always  con 
tained  a  considerable  amount  of  nitrogen.  Finally,  baryta  was  used, 
and  by  its  use  a  pure  cathartate  may  be  got.  The  method  which  was 
finally  adopted  was  as  follows:  The  fol.  senn^e  spiritu  extracta  were 
thoroughly  moistened  with  very  dilute  sulphuric  acid  in  order  to  set 
free  the  cathartic  acid  from  its  salts,  and  then  all  the  matters  soluble 
in  cold  or  hot  alcohol  were  extracted.  The  alcoholic  solution  was 
then  precipitated  with  hot  saturated  solution  of  baryta,  which  was 
added  until  it  no  longer  gave  a  precipitate.  The  whole  was  then  fil- 
tered, the  residue  well  washed,  and  having  been  put  into  a  glass  vessel 
a  stream  of  carbonic  acid  gas  was  passed  through  it  for  some  hours. 
'  American  Journal  of  Pharmacij,  1866. 
Vierteljahrschrift  f.prakt.  Phartn.,  Bd.  xvii. 
Jahresberieht  ilber  die  Fortachritte  der  Chemie,  1871. 
