420 
Studies  in  Extraction. 
$  Am.  Jour.  Pharm. 
i      June,  1921. 
velocity  of  the  extraction  wiil  become  zero.  The  extraction  of  Phyto- 
lacca is  extremely  rapid  at  the  beginning  of  the  process,  and  when 
a  volume  of  percolate  thrice  the  amount  of  the  fluidextract  equiva- 
lent to  the  weight  of  the  drug  had  been  collected,  97  per  cent,  of  the 
total  extracted  matter  had  been  dissolved  out  of  the  drug.  In  other 
words,  the  percolation  of  one  gram  with  three  millilitres  of  men- 
struum removed  97  per  cent,  of  the  total  extract  obtained. 
In  accordance  with  this  assumption  that  the  attraction  of  the 
marc  is  one  of  the  factors  which  govern  the  rate  of  extraction  of  a 
drug  a  number  of  mathematical  formulas  were  applied  for  the  pur- 
pose of  calculating  a  constant  distribution  ratio  between  menstruum 
and  marc.  The  results  in  all  cases  showed  a  progressive  variation, 
either  a  numerical  increase  or  a  decrease  and  no  constant  was  ob- 
tained. (Fig.  I.)  Other  factors  intervene,  and  these  are  probably 
the  same  as  those  which  affect  the  velocity  constant  discussed  below. 
The  results  obtained  in  the  actual  extraction  are  plotted  in  Fig. 
II,  where  the  ordinates  represent  grams  per  100  ml.  (additive),  and 
the  abscissae  gallons  of  percolate.  This  curve  shows  the  regularity 
of  the  extraction,  the  rapid  initial  extraction,  and  the  retardation 
which  sets  in  later  in  the  process.  It  may,  with  profit  be  compared 
with  the  plotted  results  of  an  extraction  of  cimicifuga  reported  by 
Lloyd,3  which  shows  the  same  general  characters.  It  will  be  noted 
that  the  cimicifuga  was  extracted  much  more  rapidly  than  in  Phyto- 
lacca. Lloyd  used  7680  grains  of  drug  and  97  per  cent,  of  the  total 
extract  was  contained  in  the  first  21  floz.  of  percolate.  In  order  to 
duplicate  that  rate  the  present  extraction  would  have  to  show  97  per 
cent,  in  the  first  six  and  one-half  gallons,  or  about  twice  the  true 
rate  of  extraction.  The  cimicifuga  yielded  about  5  per  cent,  and  the 
Phytolacca  32.75  per  cent,  of  extract;  consequently  the  difference  in 
rate  of  extraction  was  not  due  to  the  amount  of  soluble  matter  in 
the  drugs,  but  rather  to  a  difference  in  solubility.  Ic  is  thus  apparent 
that  phytolacca  is  more  easily  extracted  than  cimicifuga. 
In  attempting  to  apply  a  mathematical  treatment  to  the  rate  of 
extraction  it  was  decided  that,  since  we  have  no  quantitative  knowl- 
edge of  the  various  constituents  of  phytolacca,  the  quantity  of  ex- 
tract should  be  dealt  with  as  a  unit.  A  number  of  formulas  were 
applied,  but  all  of  them  gave  a  series  of  results  which  exhibited  the 
3  This  Journal,  59/434  (1878).  The  results  are  plotted  in  this  Journal, 
Vol.  92,  p.  857  (1920). 
