258 OXIDES. 



A. Because the air is damp; and 

 moist air oxidizes (or rusts) iron and 

 steel. 



Q. In what part of the year is it most 

 difficult to keep STOVES and FIRE-IRONS BRIGHT ? 



A. In autumn and winter; because 

 the capacity of the air for holding water 

 being on the decrease, its vapour is 

 deposited on every-thing with which it 

 comes in contact. 



Q. Why does GREASING iron prevent its 

 becoming RTJSTT ? 



A. Because grease prevents the 

 humidity of air from coming in contact 

 with the surface of the iron. 



Q. Why do not STOVES rust so frequently as 

 POKERS and TONGS ? 



A. Because stoves are generally 

 covered with plumbago, or black lead. 



Q. What is plumbago, or black lead ? 



A. A mixture of charcoal and iron 

 filings. 



A most excellent varnish to prevent rust is made of 

 1 pint of fat oil varnish, mixed with 5 pints of highly 

 rectified spirits of turpentine, rubbed on the iron or 

 steel with a piece of sponge. This varnish may be 

 applied to bright stoves and even mathematical 

 instruments, without injuring their delicate polish. 



