72 
SENNA. 
by  our  President,  who  kindly  sent  me  a  resume  of  the  work, 
translated  from  the  German  Quarterly  Journal  cf  Practical 
Pharmacy.  It  was  now  evident  that,  as  to  the  facts  I  had  labori- 
ously discovered,  I  had  been  forstalled  by  the  German  professors. 
I  therefore  abstained  from  a  minute  examination  of  the  gluco- 
side,  and  devoted  myself  to  attempting  its  preparation  by  a  cheap 
and  easy  method  adapted  to  the  purposes  of  pharmacy.  I  must 
confess  that  my  results  hitherto  have  not  been  sufficiently  good 
to  warrant  my  enlarging  at  present  upon  my  numerous  experi- 
ments in  that  direction.  I  will  give  shortly,  in  conclusion, 
Dragendorf's  results,  adding  a  few  remarks  of  my  own  on  the 
pharmaceutical  preparations  of  senna. 
The  glucoside  acid,  that  now  is  known  to  confer  on  senna  its 
purgative  property,  has  been  named  by  its  discoverers  Cathartic 
acid.  Its  formula  ,  has  been  stated  as  CigoHggNgSOgg,  which,  if 
true,  accounts  for  its  extreme  instability.  It  is  insoluble  in 
water,  strong  alcohol,  and  ether,  but  enters  readi»ly  into  watery 
solution  when  combined  with  alkaline  and  earthy  bases.  Its 
amm^onia  salts  give  brownish  flocculent  precipitates  with  salts  of 
silver,  tin,  mercury,  copper,  and  lead.  Antimonial  salts,  tannin, 
yellow  and  red  prussiates,  have  no  effect  upon  it.  Alkalies, 
aided  by  heat,  act  destructively  upon  it ;  boiled  with  a  mineral 
acid  it  splits  into  a  peculiar  kind  of  glucose  and  an  acid  that  has 
been  named  Cathartogenic.  Its  formula  is  said  to  be  CiggHggNg 
SO44.  Cathartic  acid,  in  a  combined  state  and  of  tolerable 
purity,  is  prepared  by  partially  precipitating  by  strong  spirit  a 
watery  infusion  of  senna,  concentrated  to  a  syrupy  state  by 
evaporation  in  vacuo.  The  filtrate  is  now  treated  with  a  much 
larger  bulk  of  absolute  alcohol,  and  the  precipitate  thus  obtained 
is  purified  by  repeated  solution  in  water  and  precipitation  by 
alcohol. 
To  obtain  the  pure  acid,  advantage  is  taken  of  its  colloidal 
properties  ;  the  crude  cathartate  is  dissolved  in  moderately  strong 
hydrochloric  acid,  and  subjected  to  dialysis  on  a  diaphragm  of 
parchment  paper.  The  minimum  dose  of  this  pure  acid  was 
found  to  be  about  IJ  grains,  which  caused  several  stools  with 
decided  griping. 
The  combinations  of  cathartic  acid  that  I  have  made  are,  the 
