AMbee.xT;  i872RM  |  Estimation  of  Iodine  in  Kelp  Liquors,  etc,  55& 
copper  is  increased  by  exposing  the  couple  covered  with  a  solution  of 
cupric  nitrate  to  the  air,  and  diminished  by  precipitating  in  closed 
vessels.  The  actual  amounts  of  copper  in  C,  D  and  E  being  nearly 
the  same,  indicate  that  its  presence  cannot  be  attributed  to  oxygen* 
in  the  copper  employed  ;  and,  moreover,  is  a  result  which  would  fol- 
low were  it  caused  by  dissolved  oxygen  in  the  silver  solutions,  since 
it  is  probable  they  each  contained  about  the  same  quantity  of  the  gas. 
Experiments  F  and  G  show  that  the  effect  of  saturating  the  solutions, 
with  carbonic  anhydride  prior  to  precipitation  is  to  diminish  the 
amount  of  copper  three  to  four  times,  which  doubtless  is  due  to  the 
partial  displacement  of  oxygen  by  the  more  soluble  gas.  In  experi- 
ments C  to  G,  there  existed  a  trace  of  silver  in  solution  after  the 
twenty- four  hours.  H  and  I,  being  of  short  duration,  an  excess  re- 
mained ;  and  it  is  noticeable  that,  in  every  case  where  the  silver  was, 
nearly  exhausted,  copper  was  found,  whereas,  where  there  was  an* 
excess  in  solution,  the  merest  trace  only  of  copper  existed  in  the  pre- 
cipitated metal. 
It  appears  from  the  foregoing  experiments  that  free  oxygen  is  in- 
timately connected  with  the  presence  of  copper  in  silver  precipitated? 
by  that  metal;  but,  whether  copper  exists  therein  as  cuprous  oxide- 
or  as  basic  nitrate,  would  depend  upon  at  what  stage  of  the  operation 
the  oxygen  plays  its  part.  If  the  two  actions,  i.  e.,  decomposition! 
of  silver  nitrate  by  copper,  and  cupric  nitrate  by  oxygen,  be  simul^ 
taneous,  basic  nitrate  should  be  found.  If,  however,  the  decompo- 
sition of  cupric  nitrate  be  not  effected  until  the  silver  nitrate  is  so- 
exhausted  as  to  be  incapable  of  action  on  the  produced  cuprous  oxide,, 
that  substance  should  be  found.  One  experiment  made  on  this  point 
with  a  weak  solution  of  silver  nitrate,  seemed  to  show  that  basic  ni- 
trate of  copper  did  not  exist. — London  Chem.  News,  Sept.  20,  187&. 
ON  A  NEW  PROCESS  FOR  THE  ESTIMATION  OF  IODINE  IK 
KELP  LIQUORS,  MINERAL  WATERS,  &c. 
By  E.  Sonstadt. 
The  addition  of  an  alkaline  permanganate  to  a  liquid  containing 
an  iodide  in  solution,  converts  the  iodide  into  an  iodate,  provided: 
sufficient  free  alkali,  or  alkaline  carbonate  is  present  to  prevent 
liberation  of  iodine.  This  fact  (which  I  discovered  early  in  the 
present  year,  in  the  course  of  investigations  having  for  their  object: 
