So 
Alkaloidal  Assaying. 
Am.  Jour.  Pharifl. 
Feb.,  1893. 
not  only  for  preparations  but  also  for  crude  drugs  ;  (5)  the  compara- 
tive purity  of  the  alkaloids  ;  and  (6)  closely  agreeing  results. 
In  referring  to  its  general  use  the  following  statements  are  inter- 
esting :  In  assaying  extracts  the  quantity  should  not  be  too  small, 
of  fluid  extracts  the  use  of  6  to  10  grams  overcomes  the  difficulty 
of  weighing  or  titrating  minute  quantities  of  alkaloid  and  has  the 
advantage  of  allowing  the  use  of  or  ^  //-acid  in  titrating  whereby 
the  process  is  made  easier.  The  extract  must  not  be  too  concen- 
trated, or  fallacious  and  varying  results  will  be  obtained,  whereas 
proper  dilution  insures  at  once  correct  and  agreeing  results.  For 
■extractions  the  lighter  chloroform-ether  mixture  is  preferable 
because  allowing  the  use  of  ordinary  dispensing  vials  and  not 
necessitating  the  use  of  a  separating  funnel  ;  mixtures  containing 
little  chloroform,  in  some  cases  even  pure  ether,  are  recommended 
because  of  the  greater  purity  of  the  alkaloid  ;  chloroform  or  mixtures 
containing  a  larger  quantity  of  chloroform  tend  to  extract  an 
impurer  alkaloid.  The  extract  solution  should  be  agitated  with  the 
alkaloidal  solvent  before  the  addition  of  the  alkali  (almost  exclu- 
sively water  of  ammonia),  as  this  procedure  favors  the  solution  of 
the  alkaloid  when  liberated.  In  the  majority  of  assays  the  ether- 
chloroform  solution  can  be  poured  off  clear,  in  exceptional  cases 
the  solvent  must  be  passed  through  a  dry  filter,  preventing  loss  by 
evaporation  by  covering  the  funnel.  By  placing  the  alkaloid  solu- 
tion in  a  weighed  Erlenmeyer  flask  the  solvent  can  be  distilled  off 
and  the  residue  weighed  and  then  titrated ;  this  combination  of 
weighing  the  residue  and  titrating  it,  will  serve  to  a  certain  extent 
as  a  check  and  detect  the  addition  of  cheaper  alkaloids  to  inferior 
preparations  of  the  more  expensive  drugs  ;  as  an  illustration  is  cited 
the  addition  of  cinchonine  to  raise  the  alkaloidal  value  of  an  infe- 
rior fluid  extract  of  ipecac.  Attention  is  called  to  the  fact  that  the 
weight  of  the  residue  always  indicates  a  higher  result  than  by  titra- 
tion ;  recently  Professor  Norton  and  H.  T.  Nichols  (Am.  Journ. 
Pharm.,  1892,  340)  have  proven  that  even  by  using  pure  alkaloids 
in  chloroform  solution  an  increase  in  weight  results,  and  state  that 
*'  the  increase  in  weight  is  of  importance,  has  as  yet  not  been 
explained  and  that  to  determine  the  cause  further  investigations 
will  be  made?'  The  explanation  is  very  simple :  The  alkaloid 
retains  some  chloroform  which  a  temperature  of  900  or  even  100° 
C.  will  not,  or  only  very  slowly,  dissipate  ;  this  behavior  is  due  to 
