4 
Substitute  for  EtJiyl  Alcohol. 
/Am.  Jour.  Phariu. 
\    Januar3%  1899. 
The  process  of  repercolation1  was  used  for  the  extractions,  and 
syphon  percolators — and  these  were  so  managed  that  the  mass  of 
solid  contents  was  kept  entirely  filled  with  the  menstruum  as  indi- 
cated by  a  stratum  of  menstruum  on  top  of  the  mass  and  the  perco- 
late rising  in  the  well-tube  to  near  the  level  of  the  menstruum  on 
top.  This  mass  in  saturation  was  allowed  to  stand  covered  for 
forty-eight  hours  when  the  syphon  was  put  in  place  and  started, 
being  held  so  high  as  to  draw  only  from  the  upper  part  of  the  well- 
tube,  and  at  a  rate  of  dropping  so  slow  as  to  yield  two  to  three 
fractions  of  100  c.c.  each  in  the  twenty-four  hours. 
If  this  dropping  could  be  so  slow  that  its  rate  when  multiplied 
into  the  whole  mass  would  reduce  the  downward  flow  of  the  liquid 
between  the  solid  particles  to  the  same  rate  of  downward  flow  as 
that  which  passed  through  the  particles,  then  the  percolation  would 
be'ideal,  and  one  stratum  of  menstruum  would  pass  downward  as 
a  piston,  and  the  exhaustion  would  be  complete  with  the  smallest 
quantity  of  solvent  that  could  hold  all  the  soluble  matters.  This 
principle,  underlying  all  percolation,  being  kept  in  mind,  the  rate 
was  kept  slow,  and  to  control  loss  by  evaporation  the  outer,  turned 
up]end  of  the  syphon  was  kept  well  within  the  flask  receiving  the 
fraction  of  percolate. 
Three  portions  of  500  gramme  each  of  each  powder — fine  and  coarse 
— were  taken  for  the  repercolation,  and  parallel  percolations  were 
carried  along  together,  the  fine  U.S. P.  powder  with  the  U.S. P. 
alcoholic  menstruum,  and  the  coarse  with  the  acetic  acid  men- 
struum. The  percolates  were  received  in  long-necked  100  c.c. 
flasks  remarked  for  that  capacity  at  23 0  C.  Each  fraction  as  received 
was  adjusted  to  the  mark  and  weighed,  the  weighing  being  done  to 
the  nearest  centigramme,  and  the  measuring  to  the  nearest  tenth  of 
a  cubic  centimetre. 
From  the  weight  of  each  100  c.c.  fraction  the  weight  of  the  men- 
struum was  subtracted  and  the  difference  noted.    These  differences 
1  This  process  of  repercolation  originated  with  the  writer  thirty  odd  years 
ago,  see  Proceedings  of  the  Amer.  Pharm.  Assoc.,  for  1866,  p.  85,  and  was 
elaborated  through  a  series  of  papers  on  economizing  the  use  of  alcohol  in 
extracting  drugs,  published  through  several  years'  Proceedings  for  1865,  p. 
201  ;  1867,  p.  391  ;  1870,  p.  166;  1872,  p.  182.  This  last  paper  is  a  note  "on  a 
new  form  of  percolator,  and  in  it  the  syphon  percolator  now  used  for  so  many 
years,  is  first  described  and  figured.  The  final  paper  of  this  series  is  in  Pro- 
ceedings for  1873,  P-  548. 
