ON  ALUMINIUM. 
127 
acid,  or  by  the  organic  acid3  ;  slightly  by  sulphuric  acid.  It  is 
but  little  affected  by  fusion  with  sulphur  ;  mustard  is  found  to 
act  upon  it  slightly.    Its  true  solvent  is  hydrochloric  acid. 
When  we  compare  it  in  these  respects  with  those  metals,  which 
are  acted  upon  by  most  of  these  acids  giving  salts,  which  are 
more  or  less  poisonous,  the  comparison  is  favorable  to  aluminium, 
as  its  salts,  if  formed,  are  innocuous. 
According  to  M.  C.  Tissier,  aluminium  is  not  changed  by  a 
solution  of  nitrate  or  sulphate  of  copper,  but  it  is  dissolved  by  a 
solution  of  chloride  of  copper  with  the  separation  of  metallic 
copper.  It  is  attacked,  however,  by  a  solution  of  nitrate  or  sul- 
phate of  copper  when  it  contains  chloride  of  sodium,  and  this 
proves  that  chloride  of  copper  is  formed  by  the  presence  of  the 
chloride  of  sodium.  Aluminium  is  not  attacked  by  an  aqueous 
solution  of  alum,  or  by  one  of  chloride  of  sodium,  but  a  mixture 
of  the  two  dissolves  it  with  an  evolution  of  hydrogen,  and  this 
proves  that  chloride  of  aluminium  is  contained  in  the  mixture. 
Wheatstone  long  since  showed  that  aluminium  was  as  strongly 
electro-negative  as  platinum.  Its  sonorous  qualities  are  very 
great,  like  that  of  crystal.  Various  are  the  uses  which  can  be 
made  of  the  aluminium  and  of  its  alloys  with  silver  and  copper. 
All  the  purposes  for  which  it  could  be  advantageously  employed 
in  virtue  of  its  peculiar  properties,  of  not  tarnishing  by  exposure 
to  atmospheric  agencies,  and  its  lightness  combined  with  its  ex- 
traordinary strength,  would  be  far  too  tedious  to  enumerate.  A 
few  instances  only  will  suffice  of  its  adaptability  for  philosphical 
apparatus,  for  all  articles  for  table,  for  service  and  ornament,  for 
kitchen  utensils,  for  the  works  of  clocks  and  even  watches,  for 
trappings  of  harness,  for  plate  and  door  knobs,  keys,  &c.  Its 
sonorous  qualities  render  it  valuable  for  making  bells.  In  the 
galvano-plastic  arts  it  replaces  platinum. 
Aluminium  is  most  easily  soldered  with  its  own  alloys.  The 
alloys  most  convenient  are  those  with  silver,  zinc  or  tin,  their 
point  of  fusion  being  below  that  of  aluminium.  The  soldering 
may  be  done  by  means  of  a  spirit  lamp,  and  without  any  previ- 
ous cleaning. 
Pure  aluminium  can  be  easily  distinguished  from  impure  by 
its  greater  whiteness,  its  indistinct  traces  of  crystallization  ;  oc- 
casionally one  or  two  well-defined  hexagons  can  be  recognized 
on  the  surface  of  the  ingots.    The  impure  has  a  bluish  tint  like 
