TARNISH. 259 







Q. Why does ornamental STEEL (of a purple or 

 LILAC colour) rust more readily than polished 

 WHITE steel ? 



A. Because the lilac tinge is pro- 

 duced by partial oxidation; and the 

 process which forms rust has, therefore, 

 already commenced. 



Q. How can lilac STEEL be kept FREE from 

 RUST? 



A. By keeping it in a very dry 

 place; for then no additional oxygen 

 will come in contact with it, to increase 

 its amount of rust. 



Q. Do any OTHER metals (besides iron) 

 combine rapidly with oxygen ? 



A. Yes ; copper, lead, mercury, and 

 even silver to some extent. 



Q. Wliy does COPPER TARNISH? 



A. The tarnish of copper is caused 

 by its oxidation; that is, the oxygen of 

 the air combines with the surface of the 

 copper, and instead of rusting it, covers 

 it with a dark tarnish. 



Q. Why does LEAD lose its BRIGHTNESS, and 

 become DULL and of a DARKER hue, by being 

 exposed to the air ? 



A. The vapour of the air combines 



