124  LIQUOR  OPII  COMPOSITUS. 
The  solution  thus  obtained, .  when  thoroughly  mixed  and 
assayed,  yields  but  a  small  fraction  of  one  per  cent,  more  of 
morphia  than  the  solution  when  finished,  whilst  the  morphia  ob- 
tained from  it  is  more  difficult  to  purify.  This  solution  may  be 
boiled  down  as  rapidly  as  it  is  possible  to  boil  it  without  loss  by 
splashing,  without  the  slightest  injury  to  the  morphia  salts, 
provided  the  evaporation  be  not  carried  beyond  the  point  indi- 
cated, and  provided  the  stirring  be  effectually  performed  during 
the  last  part  of  the  evaporation.  The  residue  is  in  the  form  of 
a  thin  extract.  If  this  be  placed  now  upon  a  water  bath  and 
evaporated  to  dryness,  it  is  easily  rubbed  into  a  dingy  yellowish 
brown  powder,  which  weighs  from  43  to  46  per  cent,  of  the 
opium. 
It  is,  however,  not  only  unnecessary,  but  injudicious,  to  evap- 
orate it  to  dryness,  because  the  risk  of  injury  to  the  preparation 
is  greatest  during  such  a  proceeding,  and  at  the  same  time  the 
subsequent  exhausting  with  alcohol  is  rendered  more  difficult, 
while  it  does  not  materially  increase  the  proportion  of  matters 
rejected  by  the  alcohol.  By  using  a  tared  tin  saucepan,  for 
instance,  these  steps  of  the  process  are  conveniently  and  easily 
managed. 
The  first  portion  of  alcohol  boiled  upon  this  extract  takes  up 
a  large  proportion  of  the  active  matter,  and  also  dissolves  a  por- 
tion of  matter  which  is  slowly  deposited  in  cooling.     If  the 
time  directed  be  allowed,  much  of  this  latter  will  be  deposited 
upon  the  vessel  in  a  gummy,  adherent  coat,  so  that  the  tincture 
may  be  poured  off  nearly  clear  to  the  last  drops,  without  dis- 
turbing it.    Any  attempt  to  filter  the  tinctures  is  injudicious, 
because,  before  the  deposition  is  complete,  it  would  be  defeated 
by  clogging  of  the  paper,  and  after  the  deposition  is  complete  it 
would  be  useless.    The  residue  becomes  thicker,  blacker,  and 
more  tenacious  after  each  boiling  with  the  alcohol,  and  finally, 
when  exhausted,  concretes  on  cooling  into  a  hard  brittle  mass,  of 
a  dull  black  color  and  somewhat  granular  character,  very  solu- 
ble in  water  and  very  bitter.    The  bottom  of  the  vessel  in  which 
the  alcoholic  solution  is  collected  during  this  step  of  the  pro- 
cess is  also  found,  after  the  twenty-four  hours  directed,  covered 
with  a  thick  stratum  of  this  black  matter,  whilst  the  supernatant 
tincture  is  by  this  time  perfectly  clear.    These  residues  rejected 
