AN  ESSAY  ON  SENNA. 
197 
was  exhausted  by  Ale,  again  filtered,  and  the  lime  precipitated  by 
the  cautious  addition  of  oxalic  acid.  After  filtration,  the  liquid 
was  evaporated  to  an  extractive  mass.  This,  then,  represented 
the  "  Cathartin  "  of  former  investigators.  Of  the  identity  of 
this  substance,  as  the  active  principle  of  Senna,  there  have  been 
many  reasons  for  doubt,  and  Bley  and  Diesel  considered  it  as  a 
mixture  of  "  resinous  and  extractive  matter." 
This  substance  had  a  nauseous  odor  and  taste,  its  sweetness  sug- 
gesting the  presence  of  sugar,  and  by  Trommer's  test  it  gave  imme- 
diate evidence  of  glucose.  Taken  in  doses  equivalent  to  three  and 
four  drachms  of  the  leaves  it  failed  to  evince  any  purgative  effects. 
From  this  fact,  the  writer,  as  would  seem  quite  proper,  argued 
that  the  active  principle  had  been  seized  upon  by  the  subacetate 
of  lead,  and  must  be  sought  for  in  the  precipitate,  thrown  down 
by  this  reagent  in  the  original  infusion  of  Senna. 
The  precipitate  was  therefore  thoroughly  washed  with  cold 
water,  until  traces  of  lead  were  no  longer  evident  in  the  wash- 
ings. After  being  cautiously  dried  it  was  boiled  in  alcohol. 
This  menstruum  became  of  a  deep  yellow  color,  which  turned  to 
a  brownish  red  upon  the  addition  of  an  alkali.  This  was  evapo- 
rated to  a  small  bulk,  when  there  were  deposited  on  the  sides  of 
the  dish  small  green  masses  ;  these  were  collected,  and  dissolved 
in  ether,  to  which  they  imparted  a  most  beautiful  green  tint. 
This  was  evidently  chlorophylle,  the  green  coloring  matter  of  the 
leaves.  The  concentrated  liquid,  still  containing  the  yellow  col- 
oring matter,  had  become  deep  red,  and  was  agitated  with  re- 
peated portions  of  ether,  to  which  it  imparted  a  fine  yellow  color, 
which  was  immediately  changed  to  a  delicate  pink  by  the  addition 
of  any  alkali.  In  the  original  liquid  (after  affusion  with  ether) 
there  remained  a  red,  resinous  matter.  That  these  substances 
were  but  coloring  matters,  and  in  no  wise  connected  with  the  pur- 
gative properties  of  the  drug,  was  proved  by  their  non-action 
upon  the  bowels,  in  doses  even  equivalent  to  two  ounces  of  the 
leaves.  The  yellow  resin  thus  produced  is  doubtless  that  de- 
nominated "Chrysoretin  "  by  Bley  and  Diesel,  and  possesses,  in 
common  with  chrysophanic  acid,  the  property  of  being  reddened  by 
alkalies;  it  could  not  be  obtained  in  crystalline  form,  but  remained 
as  a  resinous  mass.    It  was  insoluble  also  in  benzole,  thus  differ- 
