702  Determination  of  Morphine.        { Am'oJcTr'i9^8arm* 
The  Action  of  Barium  Hydroxide  on  Solutions  Which  Contain 
Salts  of  Morphine.  Experiment  14. — A  preliminary  qualitative  ob- 
servation showed  that  pure  crystallized  morphine  dissolved  quickly 
and  completely  when  added  to  a  clear  cold  solution  of  barium  hy- 
droxide. The  following  observations  show  (i)  that  this  action  is 
quantitative  and  that  barium  hydroxide  does  not  precipitate  mor- 
phine from  its  solution,  and  (ii)  that  when  barium  sulphate  is  pre- 
cipitated from  an  acid  solution  it  carries  down  no  morphine  salt 
with  it. 
(i)  From  a  stock  solution  of  morphine  hydrochloride  50  Cc.  was 
taken  and  diluted  to  100  Cc.  by  adding  a  clear  cold  saturated  solu- 
tion of  barium  hydroxide.  The  mixture  was  allowed  to  stand,  pro- 
tected from  the  air,  for  three  hours,  then  filtered  through  a  dry 
paper.  From  the  filtrate  50  Cc.  was  taken.  To  it  was  added  in  suc- 
cession 50  Cc.  of  dilute  sulphuric  acid,  50  Cc.  of  standard  iodine 
solution  and  enough  water  to  make  the  total  volume  200  Cc.  When 
the  periodide  had  become  crystalline  it  was  filtered  through  glass 
wool  and  50  Cc.  of  the  filtrate  was  titrated  with  standard  sodium 
thiosulphate  solution. 
(ii)  To  the  same  quantity  of  the  same  stock  solution  of  mor- 
phine hydrochloride  5  Gm.  of  crystallized  barium  hydroxide  was 
added.  The  mixture  was  allowed  to  stand  over-night,  then  acidified 
with  sulphuric  acid,  diluted  to  100  Cc.  and  filtered  through  a  dry 
paper.  To  50  Cc.  of  this  filtrate,  50  Cc.  of  standard  iodine  solution 
was  added.  The  mixture  was  later  filtered  through  glass  wool  and 
25  Cc.  of  the  filtrate  was  titrated  with  standard  sodium  thiosul- 
phate solution. 
(iii)  A  blank  experiment  was  made  using  the  same  quantities  as 
in  (i)  but  substituting  distilled  water  for  the  barium  hydroxide 
solution. 
In  all  three  cases  the  volume  of  filtrate  titrated  corresponded  to 
the  same  volume  of  morphine  hydrochloride  solution. 
Titration  results : 
Volume  of  sodium  thiosulphate  solution  required  to  decolorize : 
(i)  =945  Cc.  (ii)  =9-50  Cc.  (iii)  =9.40  Cc. 
The  agreement  of  the  results  may  be  considered  very  satisfactory 
when  the  error  introduced  by  the  large  amount  of  barium  sulphate 
precipitate  is  taken  into  consideration. 
