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CLEANma  OF  PLATINUM. 
of  Kreuznach,  in  the  saline  water  of  Dureckeim,  and  in  one  of 
the  sources  of  the  Bade — the  Umgemach. 
The  chloride  of  the  new  metal  differs  from  those  of  sodium 
and  lithium  by  the  yellow  precipitate  which  it  produces  in  the 
presence  of  bichloride  of  platinum.  It  is  distinguished  from 
potassium  by  its  nitrate  being  soluble  in  alcohol.  Introduced 
into  a  flame,  and  examined  with  a  prism,  the  vapours  of  the  new 
chloride  show  a  very  interesting  spectrum,  consisting  of  two 
blue  lines,  one  of  which,  the  fainter,  almost  corresponds  with 
the  blue  of  strontium  ;  the  other,  also  a  well  defined  blue  line, 
is  situated  a  little  further  towards  the  violet  extremity  of  the 
spectrum,  and  rivals  the  lithium  line  in  brightness  and  distinct- 
ness of  outline. — Chem.  News^  Nov.  24,  1860. 
VOLUMETRIC  ESTIMATION  OF  TANNIN. 
Muller  prepares  a  standard  solution  by  dissolving  18  grammes 
of  gelatine  and  2|  grammes  of  alum  in  320  centimetres  of  water. 
31  cubic  centimetres  of  this  solution  precipitate  1  gramme  of 
tannin.  To  extract  the  tannin  he  powders  the  substance  con- 
taining it,  places  the  powder  in  a  flask,  and  adds  sufficient  hot 
water  to  cover  it.  He  then  boils  for  a  few  minutes,  and  decants 
the  liquor  carefully  into  a  precipitating  glass.  This  operation 
is  repeated  five  or  six  times,  with  more  water,  and  at  last  powder 
and  all  are  poured  into  the  glass.  The  presence  of  the  powder 
does  not  interfere  with  the  precipitation  of  the  tannin,  but  even 
favors  the  clarification  of  the  liquor.  After  cooling,  the  standard 
solution  is  added  as  long  as  a  whitish  cloud  is  formed  in  the 
clear  liquid. — Chem.  Neivs,  Nov.  1860. 
CLEANING  OF  PLATINUM. 
To  the  Editor  of  tlie  Chemical  News. 
Sir, — A  remarkably  rapid  and  perfect  method  of  cleaning 
platinum  apparatus  consists  in  gently  rubbing  upon  the  dirty 
metal  a  small  lump  of  sodiam-amalgam.  Sodium  has  the  curi- 
ous property  of  lending  to  mercury  the  power  of  "wetting" 
platinum  in  so  complete  a  manner  that  the  positive  capillarity 
between  platinum  and  an  amalgam  containing  even  only  a  few 
