692 
Determination  of  Morphine. 
Am.  Jour.  Pharm. 
Oct.,  1918. 
Precipitation  of  Morphine  by  Ammonium  Hydroxide  under 
Various  Conditions.  Sources  and  Extent  of  Loss. — Most  standard 
methods  for  the  determination  of  morphine  depend  on  its  precipita- 
tion from  acid  solution  by  addition  of  an  excess  of  ammonium 
hydroxide  or,  what  amounts  to  the  same  thing,  from  alkaline  solu- 
tion by  ammonium  chloride.  In  the  majority  of  such  cases  alcohol 
is  also  added.  It  is  difficult  or  impossible  to  precipitate  morphine  in 
reasonably  pure  condition  from  any  solution  containing  resinous 
matter  without  the  use  of  an  organic  solvent  to  retain  the  latter. 
This  precipitation  of  morphine  is  never  quantitative,  and  some  ex- 
periments have  been  made  to  exhibit  clearly  the  extent  of  the  errors 
involved,  and  their  source. 
The  conditions  of  Experiment  8  were  arranged  to  conform  as 
nearly  as  possible  to  those  under  which  morphine  is  thrown  down  in 
Stevens's  assay  of  opium  (Pharm.  Arch.,  V,  41-45).  The  result 
closely  confirms  Stevens's  estimate  of  the  losses  involved.  A  mix- 
ture of  30  Cc.  of  water  with  8  Cc.  of  alcohol  dissolves  0.05  Gm.  of 
the  alkaloid.  From  Experiments  9  and  10  taken  together  it  may  be 
deduced  that  variations  in  the  amount  of  free  ammonium  hydroxide 
or  of  ammonium  salts  have  little  effect  on  the  solubility  of  morphine. 
The  volume  of  dilute  alcohol  is  the  same  in  both  cases,  as  is  (within 
limit  of  error)  the  loss  of  alkaloid.  But  while  the  volume  of  liquid 
is  only  one  third  of  that  used  in  Experiment  8,  the  morphine  held  in 
solution  is  proportionately  more.  This  is  to  be  accounted  for  in 
part  by  the  fact  that  the  precipitates  were  washed  with  water  in- 
stead of  a  saturated  aqueous  solution  of  morphine. 
That  water  has  an  appreciable  solvent  action  in  the  morphine  is 
clearly  shown  in  Experiments  12  and  13,  though  the  action  is  very 
slight  in  comparison  with  that  of  alcohol.  The  results  of  these  ex- 
periments are  in  fair  agreement  with  those  calculated  from  the  more 
recent  of  the  very  conflicting  data  on  the  solubilities  of  this  alkaloid. 
Experiment  11  shows  that  morphine  can  be  precipitated  from 
an  aqueous  liquid  with  little  more  loss  in  the  presence  than  in  the 
absence  of  chloroform,  and  that  the  precipitation  can  be  effected  in 
a  reasonably  short  time. 
Taken  all  together  the  writer  claims  to  have  shown  ( 1 )  That  the 
principal  loss  of  morphine  in  this  precipitation  is  due  to  alcohol 
(2)  That  ammonium  salts  and  ammonia  play  only  a  very  secondary 
part.  (3)  That  a  long  precipitation  period  is  not  necessary.  (4) 
That  a  fairly  complete  precipitation  can  be  effected  in  the  presence 
