Am.  Jour.  Pharm.  \ 
October,  1899.  / 
Alkaloidal  Assays. 
469 
tieth  normal  sulphuric  acid  is  now  carefully  added,  I  c.c.  at  a  time, 
stirring  with  a  glass  rod  and  testing  the  liquid  after  each  addition 
by  immersing  for  about  fifteen  seconds  small  strips  of  neutral  methyl- 
orange  paper.  As  soon  as  the  paper  becomes  reddish,  I  c.c.  of  the 
potassium  hydrate  solution  is  added,  and  then  again  of  the  sulphuric 
acid,  adding  now  ^  of  a  c.c.  of  the  latter  at  a  time,  till  the  paper 
becomes  reddish.  In  order  to  get  exact  results,  the  acid  and  alkali 
solutions  should  be  standardized  in  nearly  the  same  conditions  under 
which  the  titration  of  morphine  takes  place,  that  is,  using  about  175 
c.c.  of  liquid,  and  noting  the  appearance  of  the  reddish  tint  upon  the 
test  paper  at  the  point  of  neutrality.  The  strips  of  reagent  paper 
should,  of  course,  be  wet  with  the  wash-bottle  before  immersion  in 
the  beaker.  Though  the  solution  of  morphine  has  a  yellow  color 
from  some  extractive  matter,  so  that  the  end-reaction  cannot  be 
found  by  adding  a  liquid  indicator  to  the  solution,  there  is  not  the 
slightest  difficulty  in  noting  the  appearance  of  the  reddish  tint  upon 
the  cream-colored  methyl-orange  paper.  Of  course,  other  indicators, 
like  iodo-eosin  in  ethereal  solution,  etc.,  might  be  found  to  give 
equally  good  results,  but  having  found  the  dip  test  with  methyl- 
orange  paper  to  give  sharp  and  definite  results  with  this  alkaloid, 
we  have  not  experimented  upon  other  indicators. 
One  c.c.  of  twentieth  normal  acid  being  equivalent  to  0  0142 
gramme  anhydrous  morphine,  the  number  of  cubic  centimeters  of 
the  acid  consumed  by  the  alkaloid  from  2^2  grammes  opium,  mul- 
tiplied by  0-568  (==  0-0142,  gives  the  percentage  of  mor- 
phine in  the  opium. 
ESTIMATING  IN  THE  IODOMETRIC  WAY. 
When  it  is  desirable  to  control  the  alkalimetric  assay  with  an 
iodometric  one,  the  contents  of  the  beaker  are  emptied  in  a  250  c.c. 
measuring  flask,  washing  the  beaker  two  or  three  times  with  small 
quantities  of  water,  the  flask  filled  up  to  250  c.c,  about  3  or  4 
grammes  calcium  hydrate  added,  and  the  mixture  shaken  for  about 
an  hour.  This  treatment  removes  a  good  deal  of  the  coloring  mat- 
ter, but  keeps  the  morphine  in  solution.  Fifty  c.c,  which  represent 
y2  gramme  of  opium,  are  now  filtered  off  into  a  100  c.c.  flask, 
and  the  liquid  slightly  acidified  with  hydrochloric  acid.  The  liquid 
will  now  be  only  slightly  colored.  Twenty  c.c  of  the  standard  io- 
dine are  now  run  out  from  a  burette  into  the  flask,  the  latter  filled 
