130 ALUMINIUM 



other metals -which may bo present in the copper e.g. Salm-Horstmar ' found coppef 

 in the aluminium sold in Paris, and Erdmann detected zinc ; * and in every case tho 

 metal is very liable to become mixed with silicon, either from the earthenware 

 tubes, boats, or crucibles ; hence Salve'tat found, even in the aluminium prepared by 

 Devillo himself, 2-87 per cent, of silicon, 2 ! 40 of iron, 6'38 of copper, and traces of 

 lead. 



The following analyses of commercial aluminium were communicated to the British 

 Association, at its meeting in 1857, by Professor Mallet : 



Made In Paris Made in Berlin 



Aluminium. . . . 92-969 . . . 96-253 



Iron 4-882 . . . 3-293 



Silicon .... 2-149 . . . 0-454 



Titanium .... trace . . . trace 



100-00 100-00 



Alloys of Aluminium. Very small quantities of other metals suffice to destroy the 

 malleability and ductility of aluminium. An alloy containing only ^th of iron or 

 copper cannot be -worked, and the presence of J 5 th copper renders it as brittle as 

 glass. Silver and gold produce brittleness in a less degree. An alloy of 5 parts 

 of silver -with 100 of aluminium is capable of being -worked like the pure metal, but 

 it is harder, and therefore susceptible of a finer polish ; -whilst tho alloy, containing 

 10 per cent, of gold, is softer, but, nevertheless, not so malleable as the pure metal. 

 Tho presence of even ^^jth part of bismuth renders aluminium brittle in a high 

 degree. 



These statements by Tissier, 8 however, require confirmation ; for Debray states that 

 aluminium remains malleable and tough when containing as much as 8 per cant, of 

 iron, or 10 per cent, of copper, but that a larger quantity of either of these metals 

 renders it brittle. 



It is curious that only 3 per cent, of silver are sufficient to give aluminium the 

 brilliance and colour of pure silver, over which the alloy has the great advantage of not 

 being blackened by sulphuretted hydrogen. 



On the other hand, small quantities of aluminium combined with other metals 

 change their properties in a remarkable manner. Thus copper alloyed with only 

 ^th of its weight of aluminium has the colour and brilliance of gold, and is still very 

 malleable (Tissier) ; and when the aluminium amounts only to |th (i.e. 20 per cent.) 

 the alloy is quite white (Debray). See ALUMINIUM BRONZE. 



An alloy of 90 parts of copper and 10 of aluminium is harder than common 

 bronze, and is capable of being worked at high temperatures easier than tho best 

 varieties of iron. Larger quantities of aluminium render the metal harder and 

 brittle. Debray.* 



An alloy of 100 parts of silver with 5 of aluminium is as hard as the alloy 

 employed in the silver coinage, although the other properties of the silver 

 remain unchanged (Tissier). Similar alloys have likewise been prepared by 

 Dr. Percy. 4 



Messrs Calvert and Johnson describe 6 an alloy of 25 parts aluminium to 75 of 

 iron, which has the valuable property of not oxidising by exposure to moist air. 



Uses of Aluminium. No very important application of aluminium has yet been 

 made : although, at the time M. Deville's experiments were commenced, sanguine 

 hopes were entertained that aluminium might be produced at a price sufficiently 

 low to admit of its practical application on a large scale, these anticipations have 

 not been realised ; and as yet, on account chiefly of its high price, tho applications 

 which have been made of this interesting metal are but few. 



Its low specific gravity, combined with sufficient tenacity, recommends it for many 

 interesting uses. Tho fractional weights used by chemists, which are made of plati- 

 num, are so extremely small that they are constantly being lost ; their much greater 

 volume in aluminium renders this metal peculiarly suitable. In the construction of 

 the beams of balances, strength combined with lightness are desiderata ; and M. 

 Deville has had very beautiful balance-beams made of this metal ; but at present its 

 high price has prevented their extensive adoption. 



These same qualities render this metal suitable for the construction of helmets and 

 other armour ; but at present these are but curiosities, and are likely to remain so, 



1 Journal pr. Chem. Ixvii. 493. * Journal pr. Chem. Ixvii. 494. 



C. and J. Tissier, Comptes llendns, xliii. 885. * Comptee Kendus, xliii. 925. 



' Proceedings of the Koyal Institution, March 14, 1856. Phil. Mag. x. 245. 



