320      ON  ALUMINIUM  AND  ITS  CHEMICAL  COMBINATIONS. 
bules.  If  the  mass  composed  of  the  metal  and  of  chloride  of  so- 
dium (it  is  preferable  to  use  sodium)  be  heated  to  bright  redness 
in  a  porcelain  crucible,  the  excess  of  chloride  of  aluminium  will 
be  driven  off,  and  there  will  remain  a  saline  mass  having  an  acid 
reaction,  in  the  midst  of  which  will  be  found  globules,  varying 
in  size,  of  perfectly  pure  aluminium. 
This  metal  is  as  white  as  silver,  and  malleable  and  ductile  in 
the  highest  degree.  But  when  worked  it  appears  to  become 
harder,  and  its  tenacity  probably  approaches  nearly  to  that  of 
iron.  It  may  be  hardened  and  again  softened  by  annealing.  Its 
density  is  2.5J.  It  may  be  melted  and  run  out  in  the  air  with- 
out being  sensibly  oxidized.    It  is  a  good  conductor  of  heat. 
Aluminium  is  completely  unalterable  in  dry  or  moist  air.  It 
does  not  become  tarnished,  and  remains  bright  by  the  side  of 
freshly  cut  zinc  and  tin  while  the  latter  lose  their  brilliancy.  It 
is  not  acted  upon  by  sulphuretted  hydrogen.  Cold  water  has  no 
action  upon  it,  and  boiling  water  does  not  tarnish  it.  Nitric  acid 
either  diluted  or  concentrated,  and  diluted  sulphuric  acid,  when 
applied  cold,  are  also  without  action  upon  it.  Its  true  solvent 
is  hydrochloric  acid,  which  evolves  hydrogen  and  forms  sesqui- 
chloride  of  aluminium.  When  heated  to  redness  in  hydrochloric 
acid  gas,  dry  and  volatile  sesquichloride  of  aluminium  is  pro- 
duced. 
It  will  be  seen  that  a  white  metal,  unalterable  like  silver,  which 
does  not  blacken  when  exposed  to  the  air,  which  is  fusible,  malle- 
able, ductile  and  tenacious,  and  which  presents  the  remarkable 
property  of  being  lighter  than  glass,  may  be  rendered  very  use- 
ful if  it  could  be  easily  obtained.  When  it  is  considered  that 
this  metal  exists  in  considerable  quantity  in  nature,  its  ore  being 
clay,  we  can  but  wish  that  it  may  become  common.  I  have  every 
reason  to  believe  that  it  may  be  so,  for  chloride  of  aluminium  is 
decomposed  with  remarkable  facility,  at  an  elevated  tempera- 
ture, by  the  common  metals,  and  a  reaction  of  this  sort,  which  I 
am  now  conducting  on  a  larger  scale  than  a  mere  laboratory  ope- 
ration, will  decide  the  question  in  a  practical  point  of  view. — 
Pharm.  Journal,  from  Jour,  de  Pharmacie. 
