250 
Opium  Assai/. 
f  Am.  Jour.  Pharm. 
"(      May,  1882. 
In  the  weight  of  the  crystals  obtained,  the  moving  of  the  decimal 
point  of  the  metric  weight  one  figure  to  the  right,  of  course  gives  the 
percentage  of  morphia. 
This  process,  according  to  the  skill  and  care  with  which  it  is  man- 
aged, will  give  uniform  results  to  within  two  or  three-tenths  of  a  per 
cent.,  and  will  give  a  true  account  of  the  morphia  in  all  unadulterated 
opiums  probably  to  within  a  quarter  of  one  per  cent,  and  the  results 
are  believed  to  be  too  low  rather  than  too  high.  Adulterated  opiums, 
however,  are  much  more  difficult  to  assay  and  yield  crystals  which  are 
always  darker  and  less  clean,  and  therefore  the  results  are  almost 
always  too  high.  Poor  opiums,  on  the  other  hand,  are  very  easy  to 
assay,  and  usually  give  very  light  colored  clean  morphia.  The  results 
here  are  liable  to  be  too  low,  because  when  the  quantity  of  morphia  is 
small  the  alcohol  and  ammonia  used  are  proportionately  too  large,  so 
that  much  morphia  may  be  retained  in  the  mother-liquor.  Therefore,, 
when  the  morphia  comes  out  very  white  and  in  small  proportion,  the 
assay  should  always  be  repeated,  evaporating  the  solution  to  10  grams 
instead  of  to  20,  and  adding  5  cc.  of  alcohol  instead  of  10,  and  2-5  or 
3  cc.  of  ammonia  instead  of  4. 
The  lime-water  test  for  the  narcotine  in  the  results  of  the  assay  is 
quite  sufficient,  since  nothing  except  coloring  matter  is  so  likely  or  sO' 
liable  to  be  present  as  narcotine.  The  only  difficulty  is  to  know  when 
the  lime-water  has  surely  dissolved  all  that  it  will  dissolve.  This  is 
facilitated  by  having  a  very  fine  powder,  and  then  good  judgment  is 
required  to  know  the  value  or  significance  of  undissolved  residues 
when  they  are  small. 
The  above  process  is  very  easily  applicable  to  the  assay  of  such  pre- 
parations of  opium  as  the  tincture,  deodorized  tincture  and  compound 
solution.    For  the  assay  of  these  : 
Take  of  the  liquid  preparation  120  cc.  =  4  fluidounces.  Evaporate 
at  a  low  temperature  to  10  grams  =155  grains,  and  from  this  point 
proceed  exactly  as  in  in  the  above  process,  using,  however,  5  cc.  of 
alcohol  instead  of  10  and  2*5  to  3  cc.  of  ammonia  instead  of  4. 
This  quantity  of  the  liquid  preparations  is  equal  to  about  150  grains^ 
or  a  little  less  than  10  grams  of  the  opium  from  which  they  were 
made,  if  made  by  the  officinal  process.  The  yield  of  mori^hia  should 
be  not  much  less  than  1  gram  =  15'43  grains,  =  4  grains  to  the  fluid- 
ounce,  nor  more  than  1*5  gram  =  23*15  grains  =5*8  grains  to  the. 
fluidounce. 
If  the  preparations  were  made  by  assay,  and  bear  the  assay  value 
upon  the  label,  then  the  yield  of  morphia  should  agree  with  the  assay 
on  the  label  within  two  or  three-tenths  of  a  grain  to  the  fluidounce, 
or  in  proportion  to  the  skill  and  success  of  the  assay  ;  but  there  will 
always  be  some  loss. 
