AMaJrchRiPiH872M  }  Method  for  FMi mating  Morphia  in  Opium,  117 
then  iodic  acid,  and  after  the  mixture  had  stood  a  few  minutes  it  was 
shaken  with  carbon  disulphide.  The  feeble  color  of  the  latter  showed 
plainly  that  it  contained  less  than  the  usual  quantity  of  iodine. 
2.  The  experiment  was  repeated,  but  with  this  difference,  viz.,  the 
shaking  with  carbon  disulphide  was  performed  immediately  after  add- 
ing the  iodic  acid.  The  full  color  was  now  obtained,  the  liberated 
iodine  having  been  seized  by  the  disulphide  before  the  secondary  reac- 
tion could  take  place. 
3.  Similar  experiments  were  tried  with  codeine,  the  invariable  result 
being  a  diminution  in  the  amount  of  iodine  set  free. 
4.  Thebaine  was  found  to  act  in  the  same  direction  as  codeine. 
5.  Iodine  water,  when  added  to  a  slightly  acid  solution  of  papave- 
rine, produces  a  red-brown  precipitate,  which  gives  with  chloroform  a 
yellow  or  brown  solution ;  but  carbon  disulphide  abstracts  the  iodine 
from  the  compound  and  liberates  the  papaverine.  The  presence  of 
the  latter  in  the  sample  solution  is,  therefore,  of  no  consequence. 
6.  Though  solution  of  narceine  does  not  reduce  iodic  acid,  yet 
after  being  heated  with  lime  or  potash  it  has  that  effect.  But  the 
proportion  of  narceine  existing  in  opium  appears  to  be  so  minute, 
there  can  be  no  risk  of  error  from  this  source. 
The  requisite  conditions  being  now  better  understood,  the  samples 
were  examined  afresh  by  the  reduction  process,  and  this  time  the  re- 
sults were  deemed  satisfactory. 
This  sketch  of  the  course  of  the  inquiry  may  serve  to  explain  some 
parts  of  the  process  finally  adopted,  which  I  will  proceed  to  describe  : 
Apparatus. — Three  strong  tubes  of  colorless  glass,  like  ordinary 
test-tubes  in  form,  about  eight  inches  in  length,  and  of  exactly  equal 
bore,  which  should  be  about  half  an  inch.  At  first  I  used  graduated 
tubes,  but  afterwards  found  it  better  to  employ  separate  measures  of 
smaller  calibre,  viz  ,  a  pipette  to  deliver  100-grain  measures;  a  tube- 
measure  for  50  and  100  grain  measures  ;  and  a  smaller  one  for  5,  7*5 
and  10  grain-measures. 
Standard  Solution  of  Morphia. — Weigh  off  accurately  one  grain  of 
pure  and  well  dried  morphia,  and  dissolve  it  in  50  grain-measures  of 
diluted  sulphuric  acid,  B.  P.,  and  sufficient  distilled  water  to  make 
the  volume  exactly  1000  grain-measures.  This  solution  will  keep 
without  appreciable  change  for  some  weeks. 
Solution  of  Iodic  Acid. — Place  in  a  flask  100  grains  of  iodine,  100 
