AAu£st"  i^hilrm;}  '  R°mance  °f  Chemical  Elements.  573 
Ceria. 
Another  new  planet  was  discovered  in  1801  by  Piazzi  of  Pa- 
lermo, which  was  the  first  one  of  the  asteroids,  and  called  Ceres ; 
from  it  the  name  cerite  for  a  new  mineral  and  ceria  for  a  new  base 
found  by  Klaproth  and  independently  by  Berzelius  and  Hisinger  in 
1803  has  been  derived.  Like  yttria,  so  ceria  proved  to  consist  of 
several  other  elements  of  the  rare  earth  group,  whose  separation 
and  isolation  is  seen  in  Table  IV. 
Sodium  and  Potassium. 
The  salts  of  sodium  and  potassium  have  been  known  in  very 
remote  times  and  used  in  various  trades.  The  Egyptians  already 
distinguished  between  "  ordinary  alkali "  and  "  red  alkali,"  the  latter 
being  potassium  carbonate,  which  colored  the  flame  purple.  In  the 
Orient  sodium  carbonate  (and  potassium  carbonate)  was  known 
as  neter  or  bor,  and  it  was  mainly  gotten  from  the  alkali  lakes  of 
Egypt,  about  fifty  miles  from  Cairo.  In  the  Old  Testament  we  find 
*  (perhaps  the  first  reaction)  that  nether  and  vinegar  mixed  together 
are  effervescing.  The  Romans  imported  large  amounts  of  nitrum 
(sodium  carbonate)  from  Egypt  and  used  it  for  the  manufacturing 
of  soap.  From  nitrum  the  modern  terms  natrium  (sodium)  and 
niter  (saltpeter)  are  derived.  The  term  alkali  came  in  use  among 
the  alchemists,  and  is  derived  from  the  Arabic  article  al  and  kali 
=  ash,  for  alkali  or  potash  was  prepared  by  burning  of  seaweeds 
and  other  plants.  From  it  kalium  (potassium)  is  derived.  The 
Arabic  kali  =  ash  is  connected  with  kalaja  =  to  burn,  and  is  also 
found  in  Hebrew  kalah  =  burning.  Marggraf  in  1758  showed  the 
analytical  distinction  of  sodium  and  potassium  and  in  1807  Sir 
H.  Davy  succeeded  in  isolating  the  metals  by  electrolysis,  thus 
introducing  electric  methods  into  chemistry  and  laying  the  founda- 
tion for  electrochemistry. 
Calcium  and  Magnesium. 
Like  sodium  and  potassium,  so  calcium  and  magnesium  were 
first  isolated  by  electrolytical  means.  Calcium  by  Davy  in  1808,  and 
magnesium  in  1830  by  Liebig  and  Bussy,  although  Davy  had  tried 
in  vain  to  prepare  it.  The  compounds  of  calcium  were  known  in 
prehistoric  time ;  we  have  in  Latin  calx,  Greek  chalix  for  lime- 
