2 1 2  Fluid  Extracts  by  Repercolation.      { AmMJa°yu;-l8P7h8arm" 
tive  solubilities  have  been  still  too  much  overlooked,  in  favor  of  the 
earlier  and  more  simple  processes. 
Whatever  may  be  said  of  the  older  processes  in  regard  to  simplicity 
and  facility  of  application,  by  which  they  are  adapted  to  any  capacity, 
and  thus  go  into  general  use,  it  may  also  be  said  with  great  certainty 
that  under  the  ordinary  conditions  of  their  general  use,  they  do  not 
accomplish  their  object  to  a  reasonable  extent,  or  as  well  as  other  pro- 
cesses now  known  :  and  that  although  the  resulting  preparations  are 
put  forth  in  the  Pharmacopoeia  as  representing  the  drugs  minim  for 
grain,  they  do  not  really  come  near  to  this  relation.  The  variations 
in  the  quality  of  the  drugs  used,  and  the  variations  in  the  moisture 
which  they  contain,  are  elements  of  so  much  uncertainty  and  want  of 
uniformity  in  the  liquid  preparations  made  from  them,  that  it  becomes 
very  important  to  reduce  all  other  sources  of  variability  to  a  minimum. 
Repercolation,  well  applied,  leaves  little  to  be  desired  in  making  a 
liquid  preparation  that  will  fully  represent  the  drug  in  almost  any 
desired  relation  of  strength  ;  and  if  indifferently  applied,  the  inaccura- 
cies of  one  operation  are  so  made  up  and  controlled  by  those  which 
follow  that  when  the  results  of  the  difFerent  operations  or  percolations 
of  the  process  are  mixed  together  the  general  results  must  be  practically 
good  and  uniform. 
Indeed,  so  satisfactory  has  this  process  been  in  the  writer's  hands 
for  the  last  8  or  io  years,  that  the  difficulties  of  making  good  fluid 
extracts  have  been  entirely  confined  to  the  getting  of  good  materials  to 
make  them  from,  and  in  controlling  the  hygrometric  moisture  in  such 
materials  when  used.  And  in  view  of  the  satisfactory  results,  the 
inconveniences  of  the  process  and  the  disadvantage  of  having  to  carry 
a  large  stock  of  the  weak  percolate  from  each  drug, — seem  now  to  be 
of  very  much  less  consequence  than  at  first. 
Upon  finding  out  how  much  more  serious  these  inherent  objections 
to  repercolation  appeared  to  others  than  to  himself,  and  how  little  credit 
the  process  obtained  for  its  results  in  the  way  of  counterbalancing  these 
objections,  the  writer  set  himself  to  the  task  of  trying  to  simplify  the 
apparatus  and  the  process  to  the  utmost  extent  that  could  be  done 
without  sacrificing  the  principles  upon  which  the  success  depends  :  so 
that  by  doing  away  with  the  machinery  and  apparent  complication  of 
a  special  percolator,  and  as  many  details  as  possible,  the  process  might 
appear  less  objectionable  beside  the  older  methods,  and  thus  induce 
