EECEEATIYE SCIENCE. 



289 



Luganure Lead Mine, County Wicklow, Ireland. 



LEAD IN TWO PAETS. 



PAET I. — THE MOUTH OF THE MINE. 



If we want a substance wliicli shall be suffi- only can be employed. 



clently fusible to admit of its being readily 

 cast into any required form, which shall be 

 flexible enough to make into long tubes, 

 tenacious enough to form large sheets, and 

 possess at the same time the important pro- 

 perty of resisting aqueous and atmospheric 

 action, we shall find, on looking over the 

 twelve or fourteen metals which have been 

 provided for us, that there are but two 

 which combine in themselves all these ad- 

 vantages. 



These two metals are tin and lead. Now, 

 tin is expensive, for it does not occur in large 

 quantity in nature, so that we are obliged to 

 fall back upon its more abundant relation. 

 There are some purposes, moreover, for which 

 tin would be unfitted, and for which lead 

 Vol. I.— No. 9. 



19 



In some of these 

 cases, the peculiar property which is taken 

 advantage of is its easy fusibility, rendering 

 it possible to recast any objects which may be 

 imperfectly formed. If we had not lead, we 

 might still, like the Chinese, be printing from 

 wooden type. In others it is its peculiar 

 softness which constitutes its superiority for 

 some given object over any other metal. No 

 other substance, for example, is so perfectly- 

 suited for forming projectiles for rifled fire- 

 arms, as even tin bullets would soon, by 

 tearing the interior of the bore, impair the 

 accuracy of the weapon. It is this very 

 softness, too, which has recently been taken 

 advantage of in the construction of shells for 

 the Armstrong gun, the projectiles being 

 coated with lead, which, by the explosion of 



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