854 
Determination  of  Morphine. 
Am.  Jour.  Pharm. 
Dec,  1918. 
dry  or  moist  opium,  to  opium  ash  (so  often  a  constituent  of  Chinese 
pills  for  the  "  cure  "  of  the  opium  habit)  or  to  complex  pills  con- 
taining these  substances.  The  exceptions  to  this  statement  arise 
from  the  presence  of  "  interfering "  compounds,  usually  inorganic, 
and  with  ordinary  ingenuity  such  exceptions  can  be  met  by  slight 
elaborations  of  the  procedure.  Such  a  case  is  that  of  "Dover's 
Powder,"  the  examination  of  which  is  detailed  under  Experiment  38. 
Since  calculation  of  the  results  involves  no  consideration  but 
that  of  the  obvious  stoichiometrical  relations,  no  special  factors 
are  used. 
Detailed  Description  of  the  Method. 
A  convenient  weight  for  the  sample  is  6  Gm.  This  is  placed  in 
a  flask  graduated  to  contain  100  Cc.  and  is  digested  for  10  minutes 
on  the  water  bath  with  2  Gm.  (approximately)  of  calcium  carbonate 
and  enough  water  to  form  a  thin  paste.  While  warm,  the  flask 
should  be  lightly  closed  with  a  rubber  stopper.  After  digestion,  the 
flask  is  cooled,,  and  60  Cc.  of  a  cold  saturated  solution  of  barium 
hydroxide  is  added.  The  flask,  now  closely  stoppered,  is  well  shaken 
at  intervals.  After  20  to  30  minutes  water  is  added  to  bring  the 
total  volume  to  100  Cc.  The  solution  is  filtered  through  a  dry  15 
Cm.  paper,  and  an  aliquot  portion  of  the  filtrate  (50  Cc.)  is  trans- 
ferred to  a  flask  graduated  to  contain  55  Cc.  [meantime  the  residue 
on  the  filter  may  be  examined  for  meconates  as  described  in  Part 
II]. 
Sulphuric  acid  (diluted  1:5)  is  added  by  drops  till  the  solution 
is  faintly  acid  and  no  more  precipitate  forms,  the  flask  being  warmed 
on  the  water  bath  to  promote  settlement.  The  solution  is  next  made 
faintly  alkaline  by  the  cautious  addition  of  concentrated  sodium 
hydroxide  solution.  Salicylic  acid  is  next  added,  in  crystals,  till 
acidity  is  restored,  the  flask  being  warmed  after  each  addition  to 
induce  rapid  solution  of  the  acid.  When  an  acid  reaction  has  de- 
veloped, the  further  quantity  of  0.5  Gm.  of  salicylic  acid  is  added 
and  the  flask  is  heated  for  10  minutes  by  immersion  in  boiling  water. 
It  is  allowed  to  cool  to  normal  temperaure,  and  enough  water  is 
added  to  bring  the  contents  to  55  Cc.  The  liquid  is  filtered  through 
a  dry  7  Cm.  paper,  and  an  aliquot  portion  of  the  filtrate  (preferably 
50  Cc.)  is  taken  for  further  operations. 
The  clear  solution  is  evaporated  on  the  water  bath  (best  in  a 
