AmjS"iiw.arm'}  Alkaloidal  Assay.  305 
containing  a  decided  excess  of  tartaric  acid,  practically  the  whole  of 
the  NH3  will  be  precipated  along  with  nearly  all  the  albuminous 
and  gummy  matter.  The  filtrate  can  be  evaporated  to  a  solid 
extract  without  injuring  the  alkaloids  which  may  be  dissolved  with 
acidified  water,  leaving  behind  the  resins,  chlorophyll  and  fat. 
The  principle  of  eliminating  inert  matter  by  first  rejecting  the 
alcohol-insoluble  gums,  proteids,  etc.,  and  then  the  water-insoluble 
fats,  resins,  etc.,  is  of  course  not  new ;  it  has  been  applied  in  the 
U.  S.  P.  to  the  assay  of  colchicum  extract,  and  also,  in  half  measure, 
to  those  of  tincture  of  opium  and  of  fluid  extracts  of  aconite  and 
ipecac,  but  attention  may  be  drawn  to  a  few  details  necessary  for 
the  uniform  success  of  its  application : 
The  alcoholic  extract,  mentioned  in  the  process  detailed  below, 
must  be  evaporated  to  almost  dryness,  preferably  in  a  large  shallow 
basin,  which  is  then  cooled  by  floating  on  cold  water  for  a  few 
minutes.  The  subsequent  manipulation  is  simple,  in  fact  the  opera- 
tion is  a  rather  pretty  one;  10  c.c.  of  weak  sulphuric  acid  is  added 
all  at  once  and  the  basin  rotated  without  stirring.  The  excess  ot 
tartaric  acid  keeps  the  resinous  matter  in  a  finely  divided  state 
affording  easy  access  to  the  solvent ;  the  particles  of  insoluble  sub- 
stances remain  isolated  for  some  time,  but  the  continuous  rotatory 
movement  soon  causes  them  to  aggregate  and  separate  in  a  granular 
form  from  the  cloudless  liquid.  On  adding  a  fixed  alkali  to  this 
liquid  portion  (transferred  to  a  separator)  and  vigorously  shaking 
with  the  immiscible  solvent,  no  emulsification  occurs  ;  and,  after 
washing  the  "  ethereal "  extract  with  water  in  the  manner  described 
below,  its  alkalinity,  which  is  solely  due  to  presence  of  alkaloid, 
can  be  quickly  determined. 
The  assay  process  is  applicable  to  a  wide  range  of  alkaloidal 
galenicals,  and  may  be  accomplished  in  an  hour.  The  taking  of 
aliquot  portions  is  countenanced  in  the  U.S. P.  and  in  most  cases  the 
results  suffice.  In  the  table  below,  column  IV  shows  the  result  ob- 
tained by  taking  50  c.c.  of  the  filtrate,  and  the  adjoining  column 
the  result  on  working  up  the  other  half.  It  will  be  seen  that  in 
neither  case  is  the  result  much  more  than  2  per  cent,  away  from 
the  average.  However,  a  careful  operator  will  perform  the  double 
assay  in  order  to  check  at  once  the  process  and  its  application. 
Since  the  U.S. P.  now  sanctions  complete  extraction  of  the  alka- 
loids with  water-immiscible  solvent,  in  those  assays  where  ether  is 
specified  and  the  total  alkaloids  can  ultimately  be  extracted  with 
