38  Assay  of  Opium.  {Aldul^m- 
fully  dropping  upon  the  edges  of  the  filter  and  contents,  until  the 
filtrate  ceases  to  possess  a  bitter  taste. 
(The  filtrate,  although  free  from  bitterness,  will  generally  possess 
a  faint  straw-yellow  color,  due  to  the  slight  solubility  of  the  precipitate 
in  the  washing  mixture.  This  washing  can  generally  be  accom- 
plished, by  careful  manipulation,  with  15  c.c.  of  liquid  ;  in  no  case, 
however,  is  it  necessary  for  the  total  washings  to  exceed  25  c.c.) 
Add  35  c.c.  of  water  to  the  contents  of  the  capsule,  and  having 
placed  same  on  the  water-bath,  evaporate  until  the  alcohol  has  been 
completely  dissipated  and  the  residue  weighs  14  grammes,  then 
proceed  according  to  the  U.S. P.  method. 
This  additional  step  in  the  process  can  easily  be  executed  in  an 
hour's  time,  and  certainly  the  purity  of  the  morphine  so  obtained 
warrants  its  future  employment. 
It  will  be  seen  that  a  correction  by  any  of  the  commonly  used 
methods  is  entirely  unnecessary. 
The  following  table  gives  the  results  obtained  by  this  modification, 
up  to  the  present  time,  and  the  quantity  and  quality  of  the  mor- 
phine obtained  by  a  strict  adherence  to  the  U.S. P.  method  is  ap- 
pended for  the  sake  of  comparison. 
The  results  here  recorded  represent  the  average  of  closely-agree- 
ing duplicate  assays. 
The  acid  employed  in  the  titrations  of  the  different  samples  of 
morphine  was  a  ^  H.,S04,  which  was  standardized  against  sodium 
20 
carbonate  prepared  from  a  specially  purified  NaHC03,  methyl 
orange,  litmus  and  phenolphtalein  being  used  as  indicators. 
The  mean  of  the  above  results,  together  with  two  determinations, 
according  to  the  method  of  Weinig,  was  accepted  as  the  standard. 
This  acid  was  employed  in  titrating  crystallized  morphine,  prepared 
byjprecipitation  of  a  saturated  solution  of  its  sulphate  with  a  slight 
excess  of  potassium  hydrate  solution,  washing  until  free  from  sul- 
phates, and  from  potassium  spectroscopically,  carefully  drying  on 
porous  plate,  at  a  temperature  of  40°-50°  C,  then  well  washing  with 
ether  and  again  drying  to  a  constant  weight  at  the  above-mentioned 
temperature. 
The  following  results  were  obtained : 
N 
0-220  gramme  of  morphine  required  14-65  c.c.  of —  H2S04,V.S., 
20 
