1856.] on Aluminium' 221 



shows by its metallic lustre, when rubbed in an agate mortar, that 

 the oxygen has not penetrated below the surface ; magnesium, on 

 the contrary, whose oxide, like that of iron, separates immediately 

 on being formed, when similarly treated, burns away with intense 

 ignition. 



Alloys of Aluminium may become important in the arts. The 

 following, in the proportions given, were exhibited by Dr. Percy: — 



Gold 



Silver 



Tin ) alloyed with 5 per cent, of aluminium. 



Copper 



Lead 



In the gold-alloy, the presence of the small proportion of alumi- 

 nium was sufficient to convert the golden to a grey colour. 



The copper-alloy was very interesting ; it is malleable, and it 

 *' dips " of a fine golden colour. A slip of this alloy seemed to 

 have been little affected by a fortnight's exposure to the atmosphere 

 of the laboratory. Should this substance be found, on further 

 trial, capable of withstanding the corroding vapours of a London 

 atmosphere, it might be used advantageously to make " tongues " 

 for the " reed-pipes " of organs, as a material of clock-work, &c. 



Dr. Percy also exhibited other alloys of aluminium, respectively, 

 consisting of 



Tin 90— Aluminium 10 

 Copper 90 — Aluminium 5— Tin 5 

 Copper 93-7 — Aluminium 4*5— Silicium 1'8 

 Copper 80— Aluminium 20 

 (In this alloy the characteristic colour of copper was turned to white.) 



Silver 80— Aluminium 20 



(A hard and brittle alloy). 



Solder of Aluminium. — Two parts of aluminium, and one of 

 silver, will produce an aluminium solder without flux. 



Uses of Aluminium. — Both the physical and the chemical pro- 

 perties of this metal are likely to ensure its application to many 

 important uses, as soon as it can be supplied at a moderate price. 

 (At present it is sold in England at £3 per ounce.) 



M. Sainte-Claire Deville exhibited the beam of a balance, and 

 weights, specially designed for the determination of small quan- 

 tities, made of this metal, whose lightness peculiarly recommends 

 it for such a purpose. 



The same quality, as well as that of resisting corrosion, has 

 been taken advantage of by the surgeon and the dentist. The 



* Messrs. F. Grace Calvert and R. Johnson have made experiments on 

 this subject, — Phil. Mag. Ser. 4, Vol. x. p. 244, &c. 



