]  94  Characters  of  Extract  of  Calabar  Bean.    { ^^^Atriussr'"' 
We  thus  see  that  as  the  menstruum  becomes  more  aqueous  the 
greater  is  the  yield  of  extract,  and  this  is  just  what  we  would  expect 
when  we  consider  that  water  is  the  best  solvent  for  the  extractive 
matter.  It  would  naturally  be  expected  that  the  extracts  so  obtained, 
being  widely  different  as  to  quantity,  would  present  a  corresponding 
difference  of  appearance.  This  is  the  case  to  some  extent,  but  there  is 
little  distinction  between  extract  A  and  extract  jB,  I  give,  however,  a 
short  description  of  each. 
Extract  A. — A  pale  brown,  homogeneous  and  viscid  extract,  with  a 
somewhat  fatty  feeling  when  rubbed  between  the  linger  and  thumb. 
Extract  B. — Similar,  but  when  rubbed,  a  slight  stickiness  is  felt. 
Extract  C. — A  brown,  Iiomogeneous  and  stringy  extract. 
Extract  D. — A  dark  brown  extract,  with  black  patches  of  resinous 
matfer  intermixed.    The  stringiness  is  more  marked  than  in  extract  C. 
It  is  scarcely  possible  to  distinguish  between  A  and  B,  but  these 
are  distinguished  from  Cand  D  by  the  total  absence  of  any  stringy 
character.  This  characteristic  may  be  useful  as  a  rough  indication  of 
quality. 
In  their  behavior  towards  water  the  extracts  showed  marked  differ- 
ences, and  as  the  results  make  clear  why  some  commercial  samples  are 
soluble,  they  are  given  here. 
I.  Extract  ^.—0*26  gram  taken  and  triturated  with  cold  distilled 
water  (25  ec.  used).  The  extract  disintegrated  in  the  mortar  with 
difficulty ;  but  after  diligent  use  of  the  pestle  it  was  thoroughly 
•divided,  forming  a  milky  emulsion,  which  was  then  thrown  on  a  wet 
filter.  The  solution  filtered  very  slowly  and  was  colorless.  On 
evaporation  the  filtrate  yielded  0*08  gram  of  extractive,  equivalent  to 
30*76  per  cent. 
II.  Extract  B. — 0*21  gram  similarly  treated,  disintegrated  more 
readily  and  gave  a  straw  colored  emulsion,  which  filtered  a  colored 
solution,  and  on  evaporation  yielded  0'J2  gram,  or  57-14  per  cent,  of 
extractive. 
III.  Extract  C. — 0*26  gram  taken.  This  extract  was  readily  misci- 
ble  with  the  water  and  gave  a  colored  and  somewhat  opaque  solution. 
The  extractive  obtained  was  0*21  gram,  or  80*76  per  cent. 
IV.  Extract  i).— 0*372  gram  taken.  This  extract  was  also  readily 
miscible  with  the  water,  and  gave  a  pale  brown  but  clear  solution. 
The  yield  of  extractive  was  0*33  gram,  or  88*7  per  cent. 
