216 ALUMINIUM. 



up its oxygen, yet once given up, it manifests no great desire 

 to lay hold of that element again. To speak more plainly, it 

 does not rust by exposure to the air, even though the air be 

 moist. Some chemists assert that contact with boiling water 

 causes it to rust a little, whilst other chemists aver the state- 

 ment to be unfounded. From an impartial review of which 

 evidence one may safely arrive at the conclusion, that the 

 tarnishing of aluminium under these circumstances, if it take 

 place at all, must be exceedingly slight. 



Aluminium is a very light metal, its specific gravity only 

 amounting to 2'6 ; or, what will be still more comprehensible 

 to some people, supposing a vessel to be made large enough 

 to hold exactly one pound of water, it would hold one pound 

 and six-tenths of a pound of aluminium. This extremely 

 low specific gravity of aluminium, superadded to toughness 

 and malleability, renders it applicable to many useful pur- 

 poses. For example, watch-wheels have been made of it, 

 and instrument-makers talk of using it for the construction 

 of arms or beams of delicate chemical balances. Services of 

 plate have been made of it ; and no doubt when aluminium 

 is capable of being produced in still larger quantities, the 

 latter application of this most beautiful metal will be greatly 

 extended. 



Perhaps, however, the most extraordinary consideration 

 in reference to aluminium, is the enormous* amount of it this 

 world of ours contains, and its ubiquity. So far as we can 

 ascertain, about one-eighth of the earth's crust consists of 

 alumina; and alumina, as we have seen, holds more than 

 fifty per cent of aluminium. 



At this rate, no less than one-sixteenth of the solid mineral 

 portion of our planet consists of this beautiful metal. 



Clay, or the matter of clay, may be said to exist every- 

 where; and wherever clay exists, there is a storehouse of 

 aluminium. Do we wish to collect gold or silver ? we must 

 proceed to certain favoured localities to Australia, California, 



