504  Assay  of  Opium  for  Morphia.  {%fc!£a^ 
No.  2.  6.480  grams  mixed  with  chalk,  and  treated  as  above,  gave 
1*258  of  precipitate  by  ammonia  ;  of  this  1*200  was  soluble  in  alcohol, 
•267  soluble  in  bisulphide  of  carbon  and  '858  of  morphia. 
No.  3.  6"4.8o  grams  treated  with  bisulphide  of  carbon,  and  afterwards 
exhausted  with  water,  yielded  1*332  gram  of  precipitate  by  ammonia, 
of  which  1 '137  was  soluble  in  alcohol,  and  *oo8  in  bisulphide  of  carbon 
and  yielded  '880  of  morphia. 
From  this  it  will  be  seen— 
1 
2 
3 
4 
Precipitate  by  Ammonia,  . 
26  06 
19*6 
20-5 
183 
Portion  soluble  in  Alcohol,  . 
•  23-08 
i8-5 
17-2 
16-1 
"      c.s2  • 
S'S 
4' 1 
O'l 
Morphia  contained  in  precipitate,  . 
.  13-28 
13  25 
13*59 
137 
That  a  large  quantity  of  morphia  escapes  precipitation  by  ammonia  is 
a  point  strongly  to  be  remembered,  as  in  the  case  of  a  bad  opium  con- 
tainining  only  from  2  to  4  per  cent,  of  morphia,  more  morphia  might 
remain  in  the  liquid  than  was  precipitated. 
It  has  been  proposed  to  take  the  weight  of  the  precipitate  given  by 
ammonia  as  a  criterion  of  the  goodness  of  opium,  and  good  opium 
should  certainly  not  give  less  than  14  to  15  per  cent,  of  it,  but  it 
should  be  borne  in  mind  that  it  does  not  contain  more  than  half  its 
weight  of  morphia. 
If  ammonia  be  added  to  infusion  of  opium  (which  has  been  acidified 
with  hydrochloric  acid)  until  exactly  neutral,  the  resin  and  meconate 
of  calcium  are  precipitated,  whilst  soluble  hydrochlorate  of  morphia  re- 
mains in  solution  ;  the  precipitate  can  then  be  filtered  off  and  then 
ammonia  be  added  to  the  filtrate  in  slight  excess  ;  a  light- colored  pre- 
cipitate is  obtained,  which  consists  of  morphia  and  narcotina  in  a  very 
pure  form. 
Potash,  soda  and  lime,  added  to  infusion  of  opium,  cause  a  precipi- 
tate of  narcotina,  and  resin,  and  meconate  of  calcium,  but  the  mor- 
phia is  dissolved  by  the  excess  of  alkali  present.  If  the  solution  be 
filtered  quickly  the  morphia  soon  separates  out,  and  is  in  a  very  pure 
form,  but  there  is  some  loss  in  the  process,  as  I  have  never  been  able 
to  recover  by  this  means  as  much  morphia  as  by  other  processes.  Lime 
water  also  dissolves  narcotina  to  some  extent,  provided  morphia  be 
present. 
Action  of  Heat  on  Morphia. — If  morphia  or  its  salts  be  boiled  with 
water  for  some  time  the  solution  becomes  colored  ;  if  acids  in  excess 
