^""ASi^'isi^'""'}     Characters  of  Extract  of  Calabar  Bean.  193 
pound  of  the  beans  in  coarse  powder  to  be  macerated  for  forty-eight 
hours  with  a  pint  of  rectified  spirit,  then  percolated,  four  pints  of  spirit 
on  the  whole  being  used  in  the  process ;  the  percolate  is  evaporated  in 
the  usual  manner  to  a  soft  extract.  The  yield  of  extract  is  exceedingly 
small,  consequently  the  price  is  high,  and  possibly  unremunerative. 
In  the  French  Pharmacopoeia  (the  only  official  statement  on  this  point) 
it  is  stated  that  1,000  grams  of  the  beans  yield  25  to  30  grams  of  ex- 
tract of  a  pilular  consistence ;  it  must  be  borne  in  mind,  however,  that 
in  this  case  the  spirit  used  is  80  per  cent.,  while  that  of  the  British 
Pharmacopoeia  is  84  per  cent. 
Having  found  in  some  preliminary  experiments  that  the  yield  of 
extract  increased  as  the  alcoholic  menstruum  was  diluted,  I  prepared 
several  extracts  with  alcohol  of  four  strengths,  and  obtained  the  follow- 
ing results : 
Menstruum,  Rectified  Spirit. 
Extract  A. — Four  ounces  of  the  bean  in  coarse  powder  were  mace- 
rated and  percolated  according  to  the  official  directions ;  the  percolate 
measured  21  ounces. 
Half  an  ounce  of  the  percolate  evaporated  on  the  Avater-bath  yielded 
0*55  grain  of  extract,  equivalent  to  23*1  grains  from  the  four  ounces, 
or  1'32  per  cent. 
Menstruim,  Alcohol,  66  per  cent. 
Extract  B. — Four  ounces  of  bean  treated  with  this  menstruum  ;  the 
percolate  measured  19  ounces. 
Half  an  ounce  of  the  percolate  yielded  2*1  grains  of  extract,  showing 
a  total  of  79*8  grains,  or  4*56  per  cent. 
Ilenstruum,  Alcohol,  58  per  cent. 
Extract  C. — Four  ounces  of  bean  treated  with  this  menstruum  ;  the 
])ercolate  measured  19  ounces. 
Half  an  ounce  of  the  percolate  yielded  3*05  grains  of  extract ;  total 
yield  115*9  grains,  or  6*62  per  cent. 
Menstruum,  Proof  Spirit, 
Extract  D. — Four  ounces  of  bean  treated  with  this  menstruum  ;  the 
percolate  measured  19  ounces. 
Half  an  ounce  of  the  percolate  yielded  4*35  grains  of  extract ;  total 
yield  165-3  grains,  or  9*44  per  cent. 
13 
