RUST. 257 



Q. Why does lightning strike the OAK-tree 

 more frequently than any OTHER tree ? 



A. 1st Because the grain of the 

 oak, being closer than that of any other 

 tree, renders it a better conductor : and 



2ndly The sap of the oak contains a 

 large quantity of iron in solution, which 

 is a most admirable conductor of lightning. 



Q. Why does AIR rust IRON ? 



A. The oxygen of the air combines 

 with the surface of the iron, and 

 produces oxide of iron, which is gene- 

 rally called rust. 



This rust is a species of combustion, 



Q. Why does hot iron SCALE and PEEL off, 

 when struck with a HAMMER ? 



A. The oxygen of the air very 

 readily unites with the surface of the hot 

 iron, and forms a metallic oxide (or 

 rust) which scales off when struck with 

 a hammer. 



Q. Does iron RUST in DRY air ? 

 A. No \ iron undergoes no change 

 in dry air. 



Q. Why do STOVES and FIRE-IRONS become 

 RUSTY, in rooms which are not OCCUPIED ? 



z 3 



