frame,  at  an  elevation  of  12  inches,  so  as  to  allow  of  a  stand  of  8 
Bunsen  burners  to  be  so  placed  as  to  spread  a  clean  flame  over  the 
entire  length  of  the  bottom.  Each  of  these  burners  has  a  tube  f 
inch  diameter  and  5J  inches  long.  The  water  supply  pipe,  which  is 
seen  on  the  extreme  left,  is  \  inch  in  diameter,  and  has  a  valve  at  H 
which  closes  when  not  in  use.  The  two  small  water-cocks  are  designed 
to  ascertain  the  elevation  of  water  in  the  boiler.  A  f  inch  steam 
pipe  connects  the  boiler  with  the  steam  jacket. 
The  evaporating  pan  B,  set  in  an  iron  frame  20  inches  high,  consists 
of  a  concave  dish  of  tinned  copper,  1  foot  in  diameter,  6  inches  deep, 
with  a  steam  jacket  and  a  brass  flange  1J  inch  wide  riveted  on  to  it. 
The  dome,  C,  is  of  copper,  and  has  a  similar  flange,  by  which  it  is 
designed  to  be  clamped  on  to  the  evaporating  pan  when  the  apparatus 
is  used  for  distillation.  This  junction  is  made  steam  tight  by  a  coil  of 
lamp  wick  interposed  between  the  flanges.  The  drip  pipe  from  the 
steam  jacket  empties  into  the  adjacent  sink ;  it  is,  for  convenience, 
readily  separable.  The  steam  pipe  being  connected  by  a  coupling 
the  different  parts  of  the  apparatus  may  with  facility  be  separated 
from  each  other.  The  gas  burners  are  connected  by  elastic  tubing 
with  a  T  pipe  in  the  counter. 
The  first  preparation  made  in  this  apparatus  was  Extraction  Genti- 
ance,  U.  S.  P.  The  percolation  was  previously  started  in  a  cylinder  of 
tinned  iron,  with  a  stop-cock  attached.  96  troyounces  (6  lbs.  9  oz.  av.) 
of  ground  gentian,  somewhat  coarser  than  that  which  would  pass 
through  a  No.  40  sieve,  was  macerated  in  sufficient  cold  water  thor- 
oughly to  saturate  it,  then  packed  in  the  percolator  and  water  added 
till  about  a  gallon  of  dense  percolate  had  passed.    This  was  intro- 
