23  8  Fluid  Extracts  by  Rep er eolation.      { AmMa°0u,ri8^8arn 
as  the  menstruum,  and  how  far  short  of  this  to  stop  the  process  cannot 
be  indicated.  But  upon  this  small  scale  the  percolate  from  the  first 
portion  should  weigh  from  3  to  4  times  the  weight  of  the  powder  ;  and 
for  the  repercolations  from  5  to  6  times  the  weight  of  the  powder.  And 
then  with  fair  exhaustion  each  time  the  results  must  continually  check 
each  other  and  improve  until  after  10  or  12  repercolations,  a  nearly 
mathematical  accuracy  must  be  attained,  and  ever  after  be  maintained, 
all  the  variation  being  in  the  quality  of  the  drug  used.  The  writer  has 
many  series  of  repercolation,  on  various  scales  of  quantity,  which  were 
started  five  years  ago  and  suspended  from  one  season  of  the  fresh  drug 
to  another,  but  never  interrupted  to  begin  anew,  and  such  would  go  on 
indefinitely  and  with  entire  uniformity  of  result  if  the  drugs  could  be 
obtained  of  a  quality  as  uniform  as  is  the  process. 
Should  this  method  by  repercolation  become  officinal,  or  come  into 
general  use  the  apparatus  makers  would  soon  supply  a  flat-bottomed 
glass  percolator  and  cover  of  better  form  than  the  lamp  chimneys,  and 
of  all  sizes  at  moderate  prices.  If  so  no  better  form  could  be 
adopted  than  that  shown  in  the  following  cut,  if  the  bottom  be  flat  or 
very  nearly  so,  and  the  exit  tube  be  small  enough  to  receive  a  rubber 
tube  of  not  more  than  3mm.  in  bore. 
The  following  cut  is  a  modification  of  the  apparatus  adapted  to  a 
rather  larger  scale,  when  the  principles  are  applied  in  a  slightly  different 
way.  it  fulfills  the  purposes  somewhat  better  than  the  lamp  chimneys, 
and  perhaps  nearly  as  well  in  most  cases  as  the  one  represented  in  the 
cut  which  follows  it. 
The  chief  object  of  presenting  this  illustration  is  to  show  a  con- 
venient way  of  applying  the  principles  involved  in  the  syphon  perco- 
lator to  the  glass  percolator  in  common  use,  in  order  to  try  to  tempt 
those  who  have  such  percolators  to  try  the  method  in  percolation  and 
repercolation.  The  cut  is  so  plain  and  so  easily  understood  that  it 
needs  but  little  explanation.  The  percolator  is  shown  in  the  position 
of  having  been  stopped  for  the  night  lest  the  receiving  bottle  should  be 
filled  beyond  the  proper  mark.  The  syphon  here  is  made  in  two  parts, 
one  end  of  the  upper  part  being  telescoped  within  a  larger  piece  of  glass 
tubing,  and  thejunction  made  tight  by  a  short  section  of  rubber  tubing 
through  which  the  smaller  tube  is  free  to  slide.  During  maceration, 
or  when  the  percolation  is  arrested,  the  upper  part  of  the  syphon  is 
•drawn  up  until  the  liquid  will  no  longer  flow  over  into  the  bottle,  and 
