226 TUNGSTEN, ZINC 



In Canada the production of molybdenite is rapidly increas- 

 ing, and both wolfram and schulite are found in the Malay 

 States. 



Great factories have now been erected at Widnes, in South 

 Lancashire, for refining the ores and obtaining tungsten, and 

 within our own empire we can produce sufficient quantities for 

 our needs. 



ZINC is a comparatively modern metal, its usefulness not 

 having been fully discovered until early in the nineteenth 

 century. When pure it is of a bluish-white colour, but when 

 exposed to the atmosphere it loses this brilliancy and becomes 

 coated with a greyish film, though, as in the case of lead, after 

 this first tarnishing little further action takes place, so that 

 zinc is very useful for coating objects which are to be exposed 

 to a damp atmosphere. ' 



Aloysis Galvani of Bologna in the eighteenth century 

 discovered a new method of coating one metal with a dissimilar 

 one by means of electricity, and iron coated with zinc is now 

 called galvanized iron, though at present the coating is generally 

 accomplished in a similar manner to that used in the tin- 

 plate industry, i. e. by plunging the iron, when perfectly 

 cleaned and polished, into a bath of melted zinc. 



Zinc is harder than -lead or tin, but not so hard as brass 

 (an alloy of copper and zinc). At ordinary temperatures it 

 is rather brittle, but when heated to the temperature of 

 300 to 320 F. it becomes malleable and ductile. It was the 

 discovery of this property which led to its extensive use in 

 sheets. 



The ores of zinc, namely blende, or sulphide of zinc, and 

 calamine, or carbonate of zinc, frequently occur with lead ores. 



SOURCES OF SUPPLY. In Britain zinc ores are found in Cum- 

 berland, North Wales, Leadhills (in Lanarkshire), and the Isle 

 of Man, but the amount of zinc produced is small. 



In the production of zinc, as of lead, Australia stands first 

 in the empire, enormous quantities being mined at Broken 

 Hill (N.S.W.) and at other places, notably in Tasmania. 



