Chemical Change and Energy 341 



invisible, for it would give off no light if no energy were 

 released by the chemical change. Only electric lights 

 and heaters would continue to work, and even some of 

 these would fail. The electric motors in submarines 

 and electric automobiles would instantly stop ; battery 

 flashlights would go out as quickly as the fire ; no door- 

 bells would ring. In short, all forms of electric batteries 

 would stop sending currents of electricity out through 

 their wires, and everything depending upon batteries 

 would stop running. 



A fire gives out heat and light ; both are kinds of energy. 

 And it is the electric energy caused by the chemical 

 change in batteries that runs submarines, electric auto- 

 mobiles, flashlights, and doorbells. Since burning (oxida- 

 tion) is simply a form of chemical change, it is not 

 difficult to realize that chemical change releases energy. 



Why glowworms glow. When a glowworm glows at 

 night, or when the head of a match glows as you rub it 

 on your wet hand in the dark, we call the light phos- 

 phorescence. The name " phosphorus " means light- 

 bearing, and anything like the element phosphorus, 

 that glows without actively burning, is said to be phos- 

 phorescent. Match heads have phosphorus in them. 

 Phosphorescence is almost always caused by chemical 

 change. The energy released is a dim light, not heat 

 or electricity. Sometimes millions of microscopic sea 

 animals make the sea water in warm regions phos- 

 phorescent. They, like fireflies, glowworms, and will- 

 o'-the-wisps, have in them some substance that is slowly 

 changing chemically, and energy is released in the form 

 of dim light as the change takes place. Most luminous 



