Am.  Joto.  Pharm  .  ) 
Nov.  1, 1874.  J 
Extract  of  Guarana,  etc. 
507 
I  would  here  remark  that  the  fastidious  man  who  is  afraid  of  soil- 
ing his  hands  in  the  legitimate  operations  of  the  laboratory  or  the 
dispensing  counter,  would  be  quite  as  likely  to  make  a  good  black- 
smith as  a  good  pharmacist.  This  is  rather  a  homely  simile,  but  it  is 
nevertheless  a  very  expressive  one. 
It  is  one  of  the  essential  points  in  successful  percolation  to  have 
the  powder  in  just  the  right  condition  for  packing,  both  as  regards 
state  of  moisture  as  well  as  state  of  division.  Now  this  can  be  most 
thoroughly  and  satisfactorily  accomplished  by  rubbing  the  powder 
between  the  hands,  as  the  moisture  is  added,  and  working  it  not  unlike 
the  practical  housewife  does  her  flour  in  the  first  part  of  the  process 
in  making  bread.  This  thorough  intermixing  and  rubbing  uniformly 
and  equally  distributes  the  moisture,  and  also,  in  a  measure,  breaks  up 
the  lumps  and  little  aggregations  which  often  form  in  such  powders 
when  moistened.  It  is  only  by  means  of  this  kind  of  treatment,  and 
the  subsequent  use  of  the  sieve,  as  recommended  above,  that  powders 
can  be  brought  to  that  perfectly  uniform  condition  so  essential  for 
correct  packing  for  percolation. 
When  operating  with  substances  which  contain  much  coloring  mat- 
ter, such  as  the  cinchonas,  red  saunders,  etc.,  it  will  be  well  for  the 
operator  to  wear  a  pair  of  India  rubber  gloves,  which  I  have  found 
exceedingly  useful  to  protect  the  hands  in  many  operations  of  the 
laboratory. 
In  packing  the  powder  in  the  percolator  many  use  a  packing  stick } 
I  have  never  found  such  an  instrument  satisfactory.  When  practicable^ 
I  always  use  the  back  of  my  fingers  held  firmly  together;  I  can  thuSy. 
by  direct  touch,  know  how  much  pressure  I  am  using,  and  can  regulate 
it  with  greater  accuracy. 
In  packing,  special  attention  should  be  given  to  the  quantity  of 
powder  that  is  added  to  the  percolator  at  a  time,  as  well  as  to  the 
amount  of  pressure  used.  In  all  ordinany  operations  the  powder 
should  be  packed  in  small  portions  at  a  time,  in  strata  of  not  more 
than  from  a  quarter  to  a  half  inch  in  thickness.  Many  operators 
are  in  the  habit  of  introducing  the  whole  of  the  powder  into  the  per- 
colator at  once,  which  I  consider  a  great  mistake,  as  then  the  mass 
receives  the  maximum  of  pressure  at  the  very  point  at  which  it  should 
receive  the  least,  and  that  is  at  the  top. 
For  several  years  I  have  adopted  the  plan,  especially  when  operat- 
ing with  a  large  quantity  of  any  substance,  to  gradually  diminish  the 
