16 
ASSAY  OF  ALKALOIDS. 
jection  to  their  previous  removal  by  this  means.  The  precipitate 
from  iodohydrargyrate  at  once  disappears  when  the  acid  is 
neutralised,  that  with  corrosive  sublimate  turns  yellow  with  the 
alkali. 
In  place  of  the  various  proposals  for  the  separation  of  alka- 
loids from  vegetables  and  preparations  with  which  we  have  been 
favored,  I  can  recommend  the  process  of  which  I  have  given 
an  outline  in  my  paper  on  tobacco,  read  before  the  last  meeting 
of  the  American  Pharmaceutical  Association  at  Cincinnati.  It 
is  apparently  still  capable  of  improvement,  but  in  an  assay  will 
answer  all  the  purposes  of  the  delicate  method  of  Stas. 
The  process  is  founded  on  one  of  Heinrich  Rose's  suggestions 
in  his  paper  on  the  decomposition  of  iodide  of  mercury.  By 
adding  a  clear  solution  or  a  mixture  of  protochloride  of  tin  in 
caustic  alkali  to  the  precipitate,  all  mercury  is  at  once  precipi- 
tated in  the  metallic  state,  and  if  the  mixture  be  now  shaken 
with  ether,  all  that  is  soluble  in  this  menstruum  is  taken  up. 
When  the  solution  from  which  the  original  mercuric  precipitate 
has  been  obtained  was  impure  and  of  a  dark  color,  it  is  better 
at  once  to  redissolve  the  alkaline  mixture  without  the  ether,  in 
sulphuric  acid,  and  to  determine  the  alkaloid  de  novo  in  the 
filtrate.  If  the  alkaloid  be  insoluble  in  ether,  the  alkaline 
mixture  is  thickened  with  bi-carbonate  of  soda  in  large  excess, 
and  then  treated  with  alcohol ;  the  solution  in  the  latter  is  freed 
from  iodides  by  an  aqueous  and  acidulated  solution  of  acetate 
of  lead. 
I  could  have  wished  that  after  all  this  labor  I  might  say  that 
Mr.  Groves  had  left  behind  in  this  memorial  something  which  we 
could  consider  an  addition  to  our  knowledge  of  the  matter  he 
had  taken  in  hand.  It  is  easy  enough  to  tear  down  or  injure 
a  structure ;  but  whoever  lends  a  hand  in  this,  should  also  be 
prepared  with  material  for  the  new  building. 
As  it  is,  surely  my  assay  has  borne  no  damage  from  the  en- 
counter,— at  least  I  hope  that  you,  Mr.  Editor,  and  your 
readers,  will  judge  so. 
I  remain  yours  truly, 
Ferdinand  F.  Mayer. 
College  of  Pharmacy,  New  York,  December  5th,  1864. 
