54 BURNING OR OXIDATION 



and many devices have been introduced to prevent rusting. 

 A coating of paint or varnish is sometimes applied to iron in 

 order to prevent contact with air. The galvanizing of iron is 

 another attempt to secure the same result; in this process 

 iron is dipped into molten zinc, thereby acquiring a coating of 

 zinc, and forming what is known as galvanized iron. Zinc 

 does not combine with oxygen under ordinary circumstances, 

 and hence galvanized iron does not rust. 



Decay is a process of oxidation! The tree which rots slowly 

 away is undergoing oxidation, and the result of the slow burn- 

 ing is the decomposed matter which we see, and the invisible 

 gases which pass into the atmosphere. The log which blazes 

 on our hearth gives out sufficient heat to warm us; the log 

 which decays in the forest gives out an equivalent amount 

 of heat, but the heat is evolved so slowly that we are not 

 conscious of it. Burning accompanied by a blaze and intense 

 heat is a rapid process; burning unaccompanied by fire and 

 appreciable heat is a slow, gradual process, requiring days, 

 weeks, and even years for its completion. 



Still another form of oxidation occurs daily in the human 

 body! The human body is an engine whose fuel is food; the 

 burning of food in the body furnishes the heat necessary for 

 bodily warmth and the energy required for thought and action. 

 Oxygen is essential to burning, and the food fires within the 

 body are kept alive by the oxygen taken into the body at 

 every breath by the lungs. We see now one reason for an 

 abundance of fresh air in daily life. 



How to breathe. Air, which is essential to life and health, 

 should enter the body through the nose and not through the 

 mouth. The peculiar nature and arrangement of the mem- 

 branes of the nose enable the nostrils to clean, to warm, and to 

 moisten the air which passes through them to the lungs. Float- 

 ing around in the atmosphere are dust particles which ought 



