AmASusM905"m-}  Alkaloidal  Estimations.  375 
alcohol  is  expelled  before  the  liquid  is  transferred  to  the  separator 
for  extraction.  In  fluid  extract  of  colchicum  seed  and  fluid  extract 
conium  the  liquid  is  evaporated  to  dryness  with  sand,  and  then  the 
Keller  assay  method  applied.  While  in  the  assay  of  hydrastis  the 
insolubility  of  berberine  in  ether  is  depended  on  to  separate  hydras- 
tine  from  berberine,  when  the  fluid  extract  is  assayed  the  berberine 
is  precipitated  and  removed  as  the  iodide,  as  recommended  by  Gor- 
din  and  Prescott  (Am.  J.  Pharm.,  1899,  71,  p.  257). 
The  methods  for  the  assay  of  tinctures  and  extracts  are  generally 
adapted  from  those  prescribed  for  the  corresponding  fluid  extracts. 
Thus  extract  of  belladonna  leaves  is  dissolved  in  a  mixture  of  water, 
alcohol  and  ammonia  water,  and  then  treated  as  directed  for  the 
fluid  extract,  while  extract  of  physostigma  is  digested  with  a  little 
dilute  alcohol,  then  brought  to  dryness  with  sand  and  assayed. 
When  the  alkaloidal  residue  obtained  in  the  assay  is  to  be 
titrated,  generally  hematoxylin  is  to  be  used  as  indicator,  even  when 
titrating  ipecac  alkaloids.  In  some  cases  iodeosin  is  given  as  an 
alternate  ;  in  nux  vomica  it  is  specified. 
Caffeine,  colchicine,  hydrastine  and  morphine  are  determined  by 
weighing  the  free  base,  the  purity  of  morphine  being  checked  by  its 
solubility  in  lime  water.    Conine  is  weighed  as  conine  chloride. 
When  stramonium  leaves  or  its  preparations  are  submitted  to 
assay  the  alkaloidal  content  is  calculated  from  the  amount  of  acid 
required  for  the  neutralization  of  the  extracted  alkaloids;  but  this 
assay  tells  practically  nothing  about  the  identity  of  the  alkaloids. 
As  far  as  the  assay  is  concerned,  fluid  extract  of  coca  might  be  sub- 
stituted lor  stramonium  leaves  or  a  worthless  lot  of  hyoscyamus 
might  be  brought  up  to  standard  by  the  admixture  of  very  little 
belladonna  leaves.  While  such  substitution  has  been  detected  in 
commercial  products,  as,  for  instance,  in  sheep  dips,  sold  on 
their  nicotine  content,  which  have  been  found  adulterated  with 
pyridine  (J.  A.  Emery,  J.  Am.  Chan.  Soc,  1904,  26,  p.  11 13),  no 
similar  adulteration  has  to  my  knowledge  been  reported  for  medici- 
nal substances.  Although  not  requiring  an  identification  as  well  as 
an  estimation  of  the  alkaloid  of  drugs,  as  does  the  German  Pharma- 
copoeia, in  some  cases  the  U.S.P.  standards  in  a  way  do  define  the 
identity  of  the  alkaloids ;  thus  hydrastis  is  required  to  contain  not 
less  than  2-5  percent,  of  hydrastine,  belladonna  leaves  shall  yield 
not  less  than  0-35  per  cent,  of  mydriatic  alkaloids,  fluid  extract  of 
