ON  OXALATE  OF  CERIUM. 
5 
a  yellow  precipitate  of  basic  sulphate  of  the  peroxide  of  cerium 
— 2  Ce2  03,  S03  +  6  Aq — is  formed,  while  a  little  of  the  neutral 
sulphate  of  the  same  oxide,  and  all  the  lanthanium  and  didymium 
remain  in  solution. 
The  yellow  basic  sulphate  soon  settles  when  the  vessel  is  re- 
moved from  the  fire,  and  is  washed  by  decantation  with  hot  water 
acidulated  by  the  same  proportion  of  sulphuric  acid.  When 
thoroughly  settled,  the  precipitate  dissolves  readily  in  stronger 
sulphuric  acid,  forming  a  yellow  liquid  which  contains  only  per- 
oxide of  cerium.  This  I  reduce  to  protoxide  by  digesting  it 
with  a  few  crystals  of  hyposulphite  of  soda,  of  which  it  takes 
but  little  to  remove  the  yellow  color  of  the  cerium  salt  by  the 
sulphurous  acid  disengaged.  The  liquid  is  then  filtered  and  the 
oxalate  of  the  protoxide  of  cerium  precipitated  by  oxalic  acid, 
washed  with  warm  water,  filtered  and  dried. 
The  dilute  solution  of  the  cerium-metals  in  sulphuric  acid  and 
the  washings  from  the  precipitation  of  the  basic  sulphate,  retain 
a  considerable  portion  of  per-sulphate  of  cerium,  which  is  ob- 
tained for  the  greater  part  by  evaporation  of  the  fluids  to  one- 
half.  If  reduced  to  a  less  bulk,  sulphates  of  the  other  metals 
will  crystallize  out,  which  can  only  be  separated  by  again  pre- 
cipitating a  basic  persulphate  of  cerium  as  described  above. 
Oxalate  of  the  protoxide  of  cerium  is  a  snow-white  powder, 
and  consists  of  2  CeO  +  C4  06  +  6HO  =  46-14  CeO 
30-78  0 
23-08  HO. 
100-00 
It  is  insoluble  in  water,  but  dissolves  in  sulphuric  acid,  by 
which  it  is  distinguished  from  other  insoluble  salts  of  the  earths, 
and  its  solution  yields  a  precipitate  with  caustic  alkalies  even  in 
presence  of  chloride  of  ammonium,  which  is  not  soluble  in  an 
excess  of  the  precipitant. 
New  York,  Bee,  1859. 
