208 APPLICATION OIT ALUMltfltTM TO PRACTICAL PURPOSES. 



same way as gold or silver, and it can be drawn out into wire fine enough" 

 for the manufacture of lace. It is also easily run into metallic moulds, or, 

 for complicated objects, into moulds of sand. It is very finely susceptible 

 of what is technically called "matting," by being plunged into a weak 

 solution of caustic soda, and then exposed to the action of nitric acid. It is 

 also easily polished or burnished by a polishing stone steeped in a mixture 

 of rum and olive oil. When aluminium is soiled by greasy matters it can 

 readily be cleaned with benzine. Soiled by dust only, india-rubber or very 

 weak soap and water may be used. 



The process of soldering aluminium also is worthy of note. The solder 

 used is composed of zinc, copper, and aluminium, and the pieces of the 

 article intended to be joined must be "tinned," as in ordinary soldering 

 with tin, with the aluminium-solder itself. The pieces are then exposed to 

 a gas blow-pipe or other flame ; but in order to unite the solderings, small 

 tools of the metal itself must be used. Tools of copper or brass, such as are 

 employed in soldering gold and silver, are not permissible, as they would 

 form coloured alloys ; moreover, no flux whatever can be used, as all the 

 known substances employed for that purpose attack the metal, and prevent 

 the adhesion of the pieces. The use of the little tools of aluminium is an 

 art which the workman must aquire by practice, as at the moment of fusion 

 the solderings must have friction applied, the melting taking place 

 suddenly and completely. 



In comparing the price by weight of this with other metals, its greater 

 bulk must be borne in mind. Thus comparing it with silver, the bulk of a 

 given weight of aluminium is nearly four times that of the same weight of 

 silver, so that if one ounce of silver were required for an article, four 

 similar articles could be made of one ounce of aluminium Its lightness is, 

 as we have before observed, one of its principal qualities ; the specific 

 gravity of platinum is 21*5, of gold 19 - 5, tin 73, while that of aluminium 

 is only 2'6. The lightness which it communicates to the bronze, whose 

 durability, hardness, and immense strength nearly equal that of the best 

 steel, renders probable its future extensive use in the construction of build- 

 ings, the manufacture of ordnance, and other objects where strength and 

 lightness are required to be combined. 



Having witnessed how admirably the French have applied this metal to 

 ornamental and fanciful objects, it will be a matter of future interest to 

 watch the development of its applications, as a British manufacture, to 

 more solid and practical objects * — ' London Eeview.' 



* A very interesting paper on Aluminium, by Mr P. Le Neve Foster, will be found 

 in the Society of Arts Journal, vol. vii, p. 162. 



