212 
Laudanum  Assay. 
Am.  Jour.  Pharni. 
May,  1893. 
It  would  be  well,  perhaps,  to  give  verbatim  the  principal  parts 
of  the  original  article  on  "  Precipitation,"  and  "  Separation  and 
Washing,"  so  as  to  make  the  process  complete  here. 
"Precipitation. — To  the  20  grams  of  concentrated  solution  is 
then  added  half  its  weight,  or  10  grams  of  alcohol  of  not  less  than 
91  p. a,  s.g.  -815,  and  the  mixture  is  well  shaken.  Then  25  cc.  or 
17-5  grams  of  ether1  not  less  than  93  p.c,  s.g.  -725,1s  added,  and 
the  mixture  again  well  shaken.  To  this  3  5  grams  or  3-5  cc.  of 
water  of  ammonia  of  10  p.c.  strength,  s.g.  -960,  is  added,  and  the 
mixture  is  vigorously  shaken  for  10  minutes."  "At  the  end  of  the 
10  minutes'  shaking,  the  flask  is  set  aside  overnight,  or  for  not  less 
than  6  hours." 
"Separation  and  Washing. — The  ether  layer  is  poured  off  as 
closely  as  possible,  and  20  cc.  of  fresh  ether  is  added  to  the  con- 
tents of  the  flask,  and  rinsed  round  without  shaking.  This  is 
poured  off  as  closely  as  possible,  and  20  cc.  more  of  fresh  ether 
added,  rinsed  round  and  poured  off  as  before,  and  this  is  repeated 
with  a  third  portion  of  20  cc.  of  fresh  ether.  A  pair  of  counter- 
balanced filters  9  cm.  or  3-6  inches  in  diameter,  folded  at  an  angle 
slightly  wider  than  the  funnel,  and  well  wetted  with  ether,  then 
receive  the  contents  of  the  flask,  the  upper  ether  layer  being  slowly 
poured  in  first,  so  that  it  may  pass  through  before  the  paper  becomes 
wetted  with  the  watery  solution.  When  the  liquid  has  nearly 
drained  through  from  the  crystals  on  the  filters,  those  from  the  flask 
are  washed  out  onto  the  filters  by  Repeated  portions  of  water,  about 
3  cc.  at  a  time,  until  all  the  crystals  are  on  the  filters.  Then  water 
is  applied,  drop  by  drop,  from  a  pipette  held  3  or  4  inches  above  the 
funnel,  to  the  edges  of  the  filters  and  surface  of  the  crystals,  until 
they  are  fairly  clean,  and  the  mother  liquor  and  washings  together  do 
not  exceed  50  cc.  Then  5  cc.  of  a  saturated  solution  of  morphine  in 
91  per  cent,  alcohol  is  dropped  from  a  pipette,  first  upon  the  crystals 
on  the  point  of  the  filters  and  then  upon  the  edges  of  the  filters,  so 
as  to  displace  all  the  watery  solution  and  leave  them  saturated  with 
the  alcoholic  liquid.  Then  before  this  has  time  to  dry,  it  is  dis- 
placed by  dropping  on,  in  the  same  way,  5  cc.  or  more  of  ether. 
When  this  has  drained  through,  the  filters  are  closed  together  upon 
1  Prollius  was  the  first  to  use  ether  for  this  purpose,  1877,  Schweiz.  Wochen^ 
sch.  f.  Pharm.,  381  ;  Pharm.  Zeituug  ;  DraggendorfFs  Jahresberichte. 
