Am   Jonr.  Pltarm 
May,  1885. 
Active  Principle  of  Senna  Leaves. 
263 
direct  light  of  a  beautiful  emerald  greeu  and  by  reflected  light  of  a  • 
fine  red  color,  just  ay  chlorophyll  is.    Its  absorption  bands  in  the 
spectrum  are  also  very  similar  to  those  of  chlorophyll.    The  amount  j 
of  this  coloring  matter  is  very  minute,  the  principal  product,  after  the  i 
above  treatment  with  Fehling,  being  a  body  of  a  pure  reddish  brown  j 
color  which  is  insoluble  in  alkalies,  acids  and  other  menstrua,  and  j 
only  very  sparingly  soluble  in  boiling  chloroform  and  acetic  ether,  ] 
to  which  it  imparts  a  violet  cohjr.    If  cathartic  acid,  after  being  j 
decomposed  by  boiling  with  dilute  HCl,  be  treated  in  the  same  way  I 
with  Fehling,  etc.,  the  product  gives  exactly  the  same  reactions.    The  j 
reaction  could  invariably  be  obtained  with  chrysarobin,  but  not  with  j 
cathartic  acid,  the  explanation  probably  being  that  with  too  little  boil-  ' 
ing  the  body  is  not  formed,  and  with  too  prolonged  boiling  it  is  fur-  '] 
ther  decomposed.    Nothing  definite  could  be  made  out  as  regards  its  j 
relations  to  cathartic  acid.  i 
From  the  results  given  above  it  may  be  safely  inferred  that  cath-  I 
artic  acid  is  a  colored  glucoside.     On  boiling  with  acids  a  simple  i 
decomposition  into  glucose  and  the  coloring  matter  does  not  take  j 
place,  because  at  the  same  time  a  whole  series  of  intermediate  products  ■ 
are  formed,  the  investigation  and  identification  of  which  would  con-  ; 
sume  a  vast  amount  of  time.    From  the  results  of  a  few  experiments  i 
which  were  afterwards  made  it  seems  probable  that  the  difficulties  | 
would  be  lessened  by  usin^  KHO  instead  of  HCl  to  decompose  the  1 
acid.  ! 
An  ultimate  analysis  to  determine  its  formula  was  not  made,  because 
in  a  free  state  it  is  so  easily  decomposed  and  therefore  difficult  to  ; 
obtain  quite  pure,  and  also  because  it  was  so  difficult  to  obtain  its 
salts  otherwise  than  as  a  mixture  of  the  neutral  and  basic  cathar- 
tates.  All  the  purgative  substances  which  up  to  the  present  time 
have  been  separated,  either  pure  or  as  decomposition  products  of 
glucosides  from  rhubarb,  senna  and  rhamnus — viz.,  chrysophanic  acid, 
cathartic  acid,  emodin  and  many  other  unnamed  bodies — act  locally  as  , 
irritants,  and  hence  as  purgatives  when  introduced  into  the  alimentary  ; 
canal.  A  colloid  glucoside  like  cathartic  acid  has  an  especially  violent  I 
action,  as  it  is  absorbed  with  great  difficulty,  and  hence  traverses  the 
greater  part  of  the  intestines.  Its  decom])osition  products  act  in  the  ■ 
same  manner. 
In  conclusion,  I  have  to  express  my  thanks  to  Professor  Schmiede- 
berg,  of  Strassburg,  for  much  valuable  advice  while  carrying  out  this  I 
investigation. — Phar.  Jonr.  and  Trans.,  March,  1885,  p.  740.  j 
