Am.jour.^Pharm.  j       Determination  of  Morphine.  695 
0.0303  Gm.,  the  difference  being  within  the  limits  of  measurement 
error. 
The  Effect  of  Different  Indicators  011  Titrations  of  Morphine 
with  Sulphuric  Acid.  Experiment  2. — Two  portions  of  crystallized 
morphine  (0.3000  Gm.  each)  were  dissolved  separately  in  measured 
volumes  of  sulphuric  acid,  the  excess  of  which  was  titrated  with 
standard  sodium  hydroxide. 
Lacmoid  Indicator.         Methyl  Orange  Indicator. 
Total  acid  used  =25.00  Cc.  25.00  Cc. 
Acid  equivalent  to  the  alkali       =  15.13  Cc.  15.16  Cc. 
Acid  equivalent  to  the  morphine  =  9.87  Cc.  9.84  Cc. 
The  discrepancy  between  the  results  obtained  with  these  two  indi- 
cators was  therefore  0.03  Cc.  of  -fo  acid,  a  quantity  within  the  limit 
of  the  errors  of  measurement.  In  the  titration  in  which  methyl 
orange  was  used,  the  end  point  was  observed  spectroscopically  ac- 
cording to  the  method  described  by  the  writer  (Jour.  Amer.  Chem. 
Soc,  XL,  1918.  873). 
Strength  of  Iodine  Solution  in  Terms  of  Anhydrous  Mor- 
phine C17H19N03.  Experiment  3. — The  solutions  of  iodine  and 
sodium  thiosulphate  were  compared  with  one  another.  The  latter 
was  standardized  against  potassium  bichromate  and  acidified  potas- 
sium iodide. 
The  iodine  solution  was  thus  found  to.be  X  0.9692.  Purified 
anhydrous  morphine  was  weighed,  dissolved  in  acid  and  diluted  to 
such  volume  that  100  Cc.  of  the  solution  contained  0.5336  Gm.  of 
base. 
To  25  Cc.  of  this  solution  25  Cc.  of  standard  iodine  solution  was 
added.  The  mixture  underwent  no  change  of  volume.  It  was 
shaken  and  filtered  through  glass  wool.  In  25  Cc.  of  the  filtrate  the 
excess  of  iodine  was  determined  by  titration  with  sodium  thiosul- 
phate. 
Na2S203  used  =  5.28  Cc.  standard  iodine..  Therefore  morphine 
in  12.5  Cc.  of  morphine  solution  =  7.22  Cc.  standard  iodine.  There- 
fore 1  Cc.  of  X  0.9692  iodine  solution  =  0.00923  Gm.  of  an- 
hydrous morphine. 
Theory  requires  1  Cc.  =  0.00920  Gm. 
Alkalimetric  Measurement  in  Presence  of  Sodium  Tetrathionate. 
Experiment  4. — A.  A  slight  excess  of  sodium  thiosulphate  was  added 
to  50  Cc.  of  -ft  iodine  solution.    A  measured  volume  of  standard 
