198 
Commercial  Extract  of  Calabar  Bean. 
J  Am.  Jour.  Pharm. 
I      April,  1885. 
When  we  approach  the  explanation  of  the  differences  we  experience 
some  difficulty,  because  we  have  no  authorized  statement  of  what 
extract  of  Calabar  bean  should  and  and  should  not  be.  In  the  present 
case  we  may  drop  Nos.  7  and  8  out  of  the  count  as  being  hopelessly 
bad,  because  they  do  not  nearly  approach  in  alkaloidal  content  the 
average  of  the  others.  But  by  what  standard  are  we  to  judge  those 
which  remain?  Dr.  Hager,  who  of  all  authorities  consulted,  gives 
most  attention  to  the  pharmacy  of  the  bean,  states  [Pharmaceutische 
Praxis,  Suppl.,  p.  948)  that  a  dry  extract  generally  contains  from  9  to 
11  per  cent,  of  physostigmine,  and  that  2,750  grams  of  bean  contain 
about  11  grams  of  the  same  alkaloid.  But  he  previously  states  (Praxis 
vol.  ii,  p.  678)  that  the  bean  affords  about  14  per  cent  of  extract. 
Now  a  simple  calculation  will  show  that  these  figures  are  quite  conflict- 
ing, and  we  are  justified  in  setting  them  aside  as  valueless  for  our  pur- 
pose. In  the  circumstances  we  may  take  Mr.  Gibson's  extract  A,  as 
our  standard  of  comparison ;  so  doing,  and  with  his  communication 
before  us,  further  comment  on  the  want  of  uniformity  is  unnecessary 
but  I  may  be  allowed  a  few  comments  on  some  special  features  of  three 
of  the  extracts. 
The  alkaloid  obtained  from  No.  2  was  contaminated  with  rubeserin 
the  oxidation  product  of  physostigmine.  Probably  this  may  have 
arisen  from  slight  overheating  of  the  extract  during  manufacture. 
The  high  alkaloidal  content  of  Nos.  1  and  6  gives  these  extracts 
peculiar  prominence,  and  points  either  to  great  difference  in  the  strength 
of  the  bean  or  the  use  of  another  variety  of  greater  strength.  It  is 
most  unlikely  that  an  occasional  extract  of  true  Calabar  bean  should 
show  double  the  alkaloid  that  it  usually  does,  but  from  a  remark  by 
Mr.  Holmes  on  the  seed  of  Physostigma  cyllndrospermum,  it  is  more 
likely  that  extracts  prepared  from  the  cylindrical  bean  would  show 
such  a  quantity.  Mr.  Holmes  states  {Pharm.  Journ.,  [3],  ix,  913) 
that  "  on  touching  the  cotyledons  with  liquor  potassse  I  was  surprised 
to  find  that  while  the  true  beans  gave  a  permanent  pale  yellow  tint, 
the  cylindrical  ones  gave  a  deep  almost  orange  color  ultimately  turning 
to  a  greenish  hue  with  the  same  reagent."  Though  not  an  absolute 
proof,  this  is  undoutedly  a  strong  indication  of  greater  alkaloidal 
strength  possessed  by  the  cylindrical  beans,  a  strength  which  must 
necessarily  be  conveyed  to  the  extract  prepared  from  them.  Now,, 
although  extract  No.  1  has  been  prepared  with  methylated  spirit,  that 
as  a  menstruum  possesses  no  greater  solvent  powers  than  rectified 
