220 LEAD 



but unlike copper, its tenacity is small, a wire of one-twelfth 

 of an inch in thickness being unable to support a weight of 

 20 Ib. 



Another useful property of lead is its fusibility at com- 

 paratively low temperatures, and for this reason it is used 

 with tin to form solder (from Latin solidus), an alloy for 

 uniting the surfaces of two metals less fusible than itself. 



Lead united with tin forms pewter, with tin and antimony 

 type metal. 



GALENA, or sulphide of lead, a compound of lead and 

 sulphur, is, like the pure metal, of a bluish-grey colour. It 

 is the commonest of lead ores, and was supposed to exert 

 a calming influence in cases of extreme suffering, hence its 

 Greek name, galene, tranquillity, stillness of the sea. 



Mixed with the galena is nearly always a certain amount 

 of silver, and after the sulphur and other impurities have been 

 removed, the silver has to be separated from the lead. 



SOURCES OF SUPPLY. The chief lead mines of Britain are in 

 the Crossfell district of the Pennines, in the Lake District, in 

 Derbyshire, and in Lanarkshire, in the Isle of Man, in North 

 Wales, and in Wicklow. There are smelting works at Alston 

 Moor, in Cumberland, at Holywell in Flintshire, but most of 

 the imported ore is smelted at Swansea. 



As in the case of some other minerals, the mines of Britain 

 supply us with but a small proportion of the amount we need. 

 Fortunately, however, our own Dominions have an abundance 

 of the metal, though at present we buy only about half our 

 imported supplies from them. 



In the west of New South Wales, near the border of South 

 Australia, 333 miles from Adelaide, and 809 miles from 

 Sydney, amid arid and desolate country stands Broken Hill, 

 at the southern extremity of the Barrier Range of mountains. 

 Here are the most important lead and zinc mines of the 

 British Empire, and with the lead occur large quantities of 

 silver. Thousands of .miners are employed here, and the town 

 of Broken Hill has a population of 33,900 people. At Port 



