REMARKS  ON  SENNA. 
271 
loathing  experienced  by  almost  every  one  at  the  very  thought  of 
the  drug.  Whatever  interest  to  ourselves  our  own  labors  in  con- 
nection with  senna  may  possess,  we  would  not  have  thought  of 
making  them  public,  but  for  the  belief  that  they  may  be  of  some 
value  to  others,  if  only  by  confirming,  in  the  main,  the  results 
arrived  at  by  the  author  of  the  paper  in  the  Society's  Journal, 
and  those  gentlemen  whose  works  he  quotes.  We  claim  nothing 
that  can  in  the  least  lessen  the  merit  of  these  chemists,  and  the 
honor  due  to  them  for  what  they  have  so  ably  done. 
It  is  now  nearly  thirty  years  since  our  investigations  led  us  so 
far  as  to  find  that  the  principle  of  senna,  upon  which  its  cathartic 
action  depends,  could  form  a  solid  compound,  which,  in  the  dose  of 
4  or  5  grains,  possessed  all  the  beneficial  action  ofa  full  dose  of 
senna  infusion.  The  method  adopted  by  us  to  obtain  the  com- 
pound in  question,  was  this  : — The  watery  infusion  of  senna 
was  concentrated  in  a  good  vacuum  to  not  too  thick  a  syrup. 
The  extract  was  then  wrought  up  with  abundance  of  rectified 
spirit,  which  caused  a  separation  of  the  gummy  and  other  inert 
matters  in  a  solid  form,  and,  if  the  concentration  had  not  been 
carried  too  far,  nor  the  spirit  too  strong,  the  active  material  was 
entirely  contained  in  the  spirituous  liquid.  It  was  found  to  be 
of  the  utmost  importance  that  the  spirit  should  not  be  above  a 
certain  strength,  for  if  attention  to  this  point  was  neglected,  a 
portion  of  the  active  principle  (more  or  less,  according  to  the 
strength  of  the  spirit)  was  found  in  the  solid  matter  separated. 
There  is,  however,  a  sure  rule  for  knowing  when  the  spirit  is  too 
strong  or  the  extract  too  thick,  and  it  depends  on  the  circum- 
stances that  when  an  aqueous  extract  of  senna  is  mixed  up  with 
too  strong  spirit,  the  separation  produced  by  the  action  of  the 
spirit  forms  clotty  masses,  instead  of  a  more  or  less  loose  solid. 
When  the  separation  forms  clotty  masses,  the  remedy  is  to  pour 
off  the  spirit  and  mix  in  as  much  water,  with  the  clots,  as  will 
completely  disintegrate  them.  The  resulting  solution,  or  syrupy 
liquid,  is  again  treated  with  the  rectified  spirit  before  used,  and 
as  much  more  as  may  be  necessary.  By  this  means  a  spirituous 
solution  is  obtained  containing  the  whole  of  the  cathartic  princi- 
ple of  the  senna. 
