4 
ON  OXALATE  OF  CERIUM. 
purpose  is  Cerite,  a  basic  hydrated  silicate  of  the  cerium-metals, 
(cerium,  lanthanium  and  didymium,)  with  small  portions  of  lime, 
iron,  magnesia,  yttrium,  copper,  bismuth,  molybdenum,  phos- 
phoric acid.  The  oxides  of  the  cerium-metals  amount  to  67 
per  cent,  of  the  whole,  that  of  cerium  making  up  about  three- 
fifths  of  that  proportion. 
This  silicate  is  reduced  to  very  fine  powder,  placed  in  a  com- 
paratively capacious  porcelain  dish,  and  with  strong  oil  of  vitriol, 
by  the  aid  of  a  porcelain  spatula  or  glass  rod,  formed  into  a 
paste.  The  dish  is  then  put  over  a  lamp  or  sand-bath,  and 
heated  until  the  mass  ceases  to  swell  up  and  no  longer  absorbs 
any  oil  of  vitriol,  which  latter  must  be  added  very  cautiously, 
to  prevent  accidents.  When  this  reaction  is  over,  and  the  mass, 
now  a  greyish  cake,  is  cooled,  it  is  to  be  dried  and  powdered  and 
placed  in  a  Hessian  crucible,  in  which  it  is  exposed  to  the  heat 
of  an  anthracite  stove-fire,  until  it  has  assumed  a  pale  brownish 
red  color.  It  is  now  lixiviated  with  hot  water,  and  subsequently 
with  dilute  nitric  acid,  and  the  solution  treated  with  sulphuretted 
hydrogen  to  precipitate  the  heavy  metals  (copper,  bismuth, 
molybdenum).  To  the  clear  liquid  some  hydrochloric  acid  is 
added  (enough  to  hold  in  solution  the  oxalate  of  lime,  etc.,)  and 
a  solution  of  oxalic  acid,  which  precipitates  oxalates  of  protoxide 
of  cerium,  and  of  oxide  of  lanthanium,  and  didymium  in  form  of 
curdy  flakes,  soon  falling  to  the  bottom  as  a  pale,  pinkish  crystal- 
line powder.  This  is  washed  with  warm  water,  then  transferred 
to  a  mortar  and  formed  into  a  paste  with  one  half  the  weight  of 
the  mineral  in  carbonate  of  magnesia,  which  paste  is  dried  on  a 
porous  fire-brick,  then  rubbed  fine,  and  calcined  in  an  open  stove 
until  the  powder  has  assumed  the  color  of  cinnamon.  In  this 
condition  it  contains  all  cerium  in  the  form  of  peroxide,  which 
readily  dissolves  in  concentrated  nitric  acid,  carefully  to  be 
added  in  a  beaker,  to  prevent  loss  by  effervescence,  and  heated 
by  the  water-bath.  This  solution  is  freed,  to  some  extent,  of  the 
large  excess  of  acid  by  evaporation  in  the  same  vessel,  and  after 
due  dilution  with  some  water  is  poured  into  a  vessel  containing 
boiling  water  to  which  a  little  more  than  J  per  cent,  of  oil  of 
vitriol  has  been  added.  There  should  be  about  a  quart  of  water 
to  every  ounce  of  the  mineral  worked.  When  the  cerium-metals 
in  solution  are  thus  brought  together  with  dilute  sulphuric  acid, 
