314 
Su  bstitu  te  for  A  Icohol. 
Am.  Jour.  Pharm. 
July,  1900. 
successive  fractions  of  100  c.c.  each,  each  fraction  weighed,  and  the 
weight  of  ioo  c.c.  of  the  menstruum  subtracted  to  get  the  series  of 
progressive  differences. 
Then  a  parallel  process  was  managed  exactly  in  the  same  way  at 
the  same  time  with  a  io  per  cent,  acetic  acid  menstruum,  giving 
the  parallel  column  of  differences  of  the  second  portion  of  the 
table. 
Grammes. 
The  weight  of  ioo  c.c.  of  officinal  U.S. P.  menstruum  for  buck- 
thorn, at  average  room  temperature,  is        .    95  08 
100  c.c.  of  10  per  cent,  acetic  acid  menstruum  is  ioi'i9 
For  cascara,  100  c.c.  U.S. P.  menstruum  (''  Diluted  Alcohol")  is  93*48 
100  c.c.  of  10  per  cent,  acetic  acid  is  101*19 
The  first  four  fractions  of  percolate  from  each  of  the  four  percola- 
tions were  added  together  and  reserved. 
The  remaining  thirteen  fractions  were  together  evaporated  on  a 
water-bath  to  60  or  70  c.c.  of  extract  and  this  was  dissolved  in  the 
reserved  portion  and  the  whole  was  made  up  to  500  c.c.  by  the 
addition  of  fresh  menstruum  to  finished  fluid  extract. 
The  500  c.c.  of  finished  fluid  extract  from  each  menstruum 
weighed  as  follows,  and  gave  the  following  proportion  of  nearly  dry 
extract : 
Per  Cent. 
Buckthorn  by  U.S. P.  menstruum,  5  r3'o  grammes  extract     .   .  .  .22*3 
"        "  acetic  acid    "         542'i       "  "   22-5 
Cascara      "  U.S. P.  11         527-i       "  "   32*5 
"  "  acetic  acid     "         565-5       "  "       ....  427 
The  finished  fluid  extract  of  buckthorn  by  acetic  acid  contained 
8-8  per  cent,  of  free  acid. 
That  of  cascara,  97  per  cent. 
Fluid  extracts  made  by  repercolation  gave  of  free  acid — from 
buckthorn,  7-7  per  cent. — from  cascara,  7-8  per  cent. 
The  percolation  having  been  carried  to  practical  exhaustion  in 
both  varieties,  the  fluid  extracts  must  be  accepted  to  represent  the 
value  of  the  drugs,  and  this  value  is  contained  in  cascara  in  a  much 
larger  proportion  of  extract.  But  this  is  due  not  only  to  difference 
of  menstruum,  but  also  to  difference  of  fineness  of  the  powder  per- 
colated. The  U.S. P.  directs  buckthorn  in  No.  40  powder,  and  cas- 
cara in  No.  60,  and  for  this  reason  the  latter  yields  the  larger  pro- 
portion of  extract,  and  makes  any  close  comparison  of  degree  and 
