AmAj?dTi92hiarm' }    Microchemical  Test  of  Iodic  Acid.  -271 
tion  and  the  volumetric  titration  with  litmus,  agree  almost  exactly, 
if  the  number  334  is  admitted  as  the  coefficient,  which  is  the  molecu- 
lar weight  of  strychnine.  It  appears  then  that  nux  vomica  contains 
much  more  strychnine  than  brucine.  It  is  the  last  point  that  I  pro- 
pose to  determine  in  a  further  study. 
THE  CHARACTERISTIC  MICROCHEMICAL  TEST  OF 
IODIC  ACID  WITH  AMMONIA  GAS* 
M.  Deniges  1  has  shown  that  iodic  acid  can  be  employed  to  char- 
acterize, by  microchemical  means,  the  soluble  or  insoluble  compounds 
of  calcium,  strontium  and  barium;  this  reagent  does  not  give  satis- 
factory results  with  the  salts  of  potassium  or  of  ammonium,  but  it 
does  react  with  ammonia  gas ;  if  a  glass  slide  carrying  a  small  drop 
of  a  solution  of  iodic  acid  is  exposed  for  a  short  time  to  the  open 
mouth  of  a  bottle  of  ammonia,  the  little  drop  will  get  cloudy  with 
flat,  quadratic  plates  of  ammonium  iodate,  which  act  on  polarized 
light  and  are  easily  recognized  under  the  microscope.  The  reaction 
is  characteristic,  no  volatile  amine  giving  it. 
When  it  is  desired  to  apply  this  reaction  to  the  investigation 
and  to  the  identification  of  salified  ammonia  in  a  solution,  a  drink- 
ing water,  etc.,  a  certain  quantity  is  evaporated  until  reduced  to  1  cc, 
which  is  introduced,  with  .50  Gm.  calcined  magnesia  into  a  short 
glass  tube,  3  to  4  cm.  in  length  and  of  a  diameter  of  15  to  25  mm., 
and  enlarged  rim,  of  a  shape  so  that  it  is  possible  to  maintain  it 
upright  in  a  sand  box  serving  as  a  support.  There  is  laid,  on  the 
middle  of  a  slide  object-holder,  a  minute  drop  of  a  solution  of  iodic 
acid  not  exceeding  2  to  3  mm.  in  diameter,  the  tube  is  covered  with 
this  inverted  slide,  the  little  drop  facing  the  axis  of  the  tube ;  at  the 
end  of  a  rather  short  time,  the  glass  slide  is  examined  under  the 
microscope.  If  the  liquid  residue  contained  in  the  tube  contains 
only  1  mgr.  of  salified  ammonia,  it  exhibits,  at  the  end  of  a  few 
minutes,  the  presence  of  quadratic  crystals  of  ammonium  iodate 
corresponding  to  the  formula  NH4IO3. 
^Translated  from  Repertoire  de  Pharmacie,  August,  1920,  page  229.  By 
V.  O.  Homerberg. 
lComptes  rendus  de  VAcademie  des  Sciences,  July,  1920. 
