Davy  in  1808;'  but  little  was  known  of  its
properties  until  Dr  Matthiessen  formed  it  by
the  aleetroljtic  decomposition  of  the  chloride
of  calcium.
Prep.  1.  By  the  action  of  a  powerful  voltaic
current  upon  a  paste  of  pure  lime  in  contact
with  mercury,  as  in  the  original  method  of
preparing  barium.
2.  By  the  electrolysis  of  chloride  of  calcium
in  a  state  of  fusion.
3.  (Caron.)  Fused  chloride  of  calcium  in
powder,  300 parts;  distilled  zinc,  finely  granu-
lated, 400  parts ;  sodium,  in  small  pieces,  100
parts;  the  whole  placed  in  a  crucible  and
heated  to  redness  in  an  ordinary  furnace.  The
action  is  very  feeble  at  first,  but  after  some
time  zinc  flames  arise.  The  heat  must  now
be  moderated  to  prevent  the  volatilisation  of
the  zinc,  but  at  the  same  time  it  must  be
maintained  as  high  as  possible.  When  the
crucible  has  remained  in  this  state  for  about  a
quarter  of  an  hour  it  may  be  withdrawn.  On
cooling,  a  metallic  button  will  be  found  at  the
bottom.  This  alloy  of  zinc  and  calcium,  which
generally  contains  from  10  to  15§  of  the  latter
metal,  must  be  placed  in  a  coke  crucible  and
heated  until  the  whole  of  the  zinc  is  driven
off.  The  alloy  should  be  in  pieces  as  large  as
possible.  When  proper  precautions  have  been
observed  a  button  of  OALCITTU  is  obtained,
only  contaminated  with  the  foreign  metals
contained  in  the  zinc.
Frop.,  S;e.  The  metal  belongs  to  the  group
which  includes  baeium,  steontium,  and  mas-
NESIUM;  it  is  of  a  light  yellow  colour;  is
rather  harder  than  lead,  and  very  malleable.
