468 
Alkaloidal  Assays. 
f  Am.  Jour.  Pharm. 
I     October,  1&99. 
percolator,  in  the  bottom  of  which  a  plug  of  cotton  has  been  placed. 
The  jar  is  rubbed  out  several  times  with  small  quantities  of  the 
sodium  chloride,  the  rinsings  added  to  the  percolator,  and,  having 
placed  a  plug  of  cotton  and  a  piece  of  glass  on  the  top  of  the  powder, 
the  opium  is  extracted  with  benzol  by  percolating  very  slowly, 
until,  upon  evaporating  ten  drops  of  the  percolate  on  a  watch-glass, 
and  taking  up  the  residue  with  ten  or  twelve  drops  of  very  slightly 
acidulated  water,  no  turbidity  appears  by  the  addition  of  two  drops 
of  the  iodine  test  solution.  After  the  narcotine,  thebaine,  codeine 
and  most  other  alkaloids  have  in  this  way  been  completely  removed 
by  the  benzol,  the  receiver  is  taken  away1  and  a  shallow  evaporat- 
ing dish  placed  under  the  percolator. 
The  percolation  is  now  continued  slowly  with  the  mixture  of  alco- 
hol and  chloroform,2  until  ten  drops  of  the  percolate,  tested  as  above, 
give  no  reaction  for  alkaloids.  The  evaporating  dish  is  now  put  into 
a  good  current  of  air,  and  left  over  night,3  or  until  the  solvent  has 
disappeared.  The  bottom  of  the  dish  will  then  be  found  to  be  cov- 
ered with  a  good  crop  of  crystals  intermixed  with  a  little  resinous 
matter. 
ESTIMATING  IN  THE  ALKALIMETRIC  WAY. 
Fifty  c.c.  of  the  twentieth  normal  sulphuric  acid  are  now  carefully 
run  out  from  a  burette  into  the  evaporating  dish,  the  contents 
rubbed  well  with  a  pestle  till  everything  is  detached  from  the  bot- 
tom and  sides  of  the  dish,  and  then,  without  filtering,  poured  into  a 
tall,  narrow  measuring  cylinder.  The  dish  is  then  carefully  washed 
several  times  with  small  quantities  of  water,  the  washings  added  to 
the  cylinder,  and  the  latter  filled  up  to  make  90  c.c.  After  shaking 
well  a  few  minutes,  and  setting  aside  till  solid  particles  have  set- 
tled down,4  75  c.c,  representing  2^  grammes  of  the  opium,  are  fil- 
tered off  into  a  beaker  holding  some  250  or  300  c.c,  about  50  c.c. 
of  water  added,  and  then  35  or  40  c.c.  of  the  twentieth  normal 
potassium  hydrate  run  out  from  a  burette  into  the  beaker.  Twen- 
1  The  benzol,  of  course,  can  be  recovered  by  distillation,  and  used  over  and 
over  again. 
2  vSee  Burg,  Ztschr.  anal.  Chem.,  19,  p.  222. 
3  This  makes  the  whole  assay  occupy  about  two  days  and  two  hours,  if  it  be 
started  in  the  morning. 
4  The  filtration  is  much  accelerated  if  the  waxy  particles  are  prevented  from 
entering  the  filter. 
