MAGNESIUM,  ITS  PREPARATION,  ETC."" 
not  hitherto  been  ascertained  ;  it  is  a  new  fact  which  still  further 
approximates  zinc  and  magnesium,  and  gives  them  an  additional 
property  in  common.  Magnesium  is  volatile,  like  zinc,  and 
nearly  at  the  same  temperature.  Thirty  grammes  of  it  have 
been  distilled  with  ease  in  charcoal  vessels.  When  the  mag- 
nesium is  pure  it  leaves  no  residue,  and  the  sublimed  metal  is 
white  and  surrounded  by  a  small  quantity  of  oxide.  When  it  is 
impure,  it  leaves  in  the  charcoal  tray  a  certain  quantity  of  very 
light  and  complex  black  matter,  and  the  distilled  magnesium  is 
covered  with  little  colorless,  transparent  needles,  which  are 
rapidly  destroyed  with  formation  of  ammonia  and  magnesia,  in- 
dicating the  probable  existence  of  a  nitruret  of  magnesium  anal- 
ogous to  the  remarkable  bodies  already  discovered  by  Wohler 
and  Rose  for  a  certain  number  of  simple  bodies. 
Magnesium  fuses  at  a  temperature  very  near  that  of  the  fusion 
of  zinc.  At  a  temperature  a  little  higher  it  ignites,  producing  a 
brilliant  flame,  in  the  midst  of  which  indigo-blue  tufts  are  seen, 
especially  when  a  jet  of  oxygen  is  thrown  upon  the  fused  metal 
from  an  oxyhydrogen  blowpipe.  The  combustion  of  magnesium 
is  accompanied  by  all  the  phenomena  observed  with  zinc,  deno- 
ting a  volatile  metal,  the  oxide  of  which  is  fixed  and  infusible  ; 
a  brilliant  flame,  a  deposition  of  magnesium  flakes  and  a  rapid 
combustion. 
The  density  of  magnesium  is  1-75.  The  malleability  and 
ductility  of  magnesium,  and  the  dependent  physical  properties, 
are  still  under  investigation,  as  well  as  its  electrical  conductibility, 
which  is  interesting  on  account  of  its  extreme  lightness.  It  files 
*  very  easily  and  burnishes  wonderfully.  It  resists  the  air  very 
well,  especially  when  it  is  pure  and  its  surface  is  polished ;  it  is 
therefore  comparable  in  this  respect  with  zinc,  which  perhaps  is 
a  little  more  resistant. 
Magnesium  may  be  prepared  by  the  process  employed  for 
aluminium,  which,  however,  must  be  slightly  modified,  as  mag- 
nesium is  lighter  than  the  scoria  from  which  it  is  produced.  600 
grms.  of  carefully  prepared  chloride  of  magnesium  are  mixed 
with  100  grms.  of  fused  sea-salt  (or  better,  of  a  mixture  of  chlo- 
ride of  sodium  and  potassium)  and  100  grms.  of  pure  fluoride  of 
calcium,  the  whole  previously  powdered.  100  grms.  of  sodium 
in  fragments  are  added  and  mixed  intimately  with  the  powdered 
