46 CHEMICAL ACTION. 



Q. Why does a BLUISH FLAME sometimes 

 flicker on the surface of hot cinders ? 



A. Gas from the hot coals at the 

 bottom of the grate mixing with the 

 carbon of the coals above, produces 

 an inflammable gas (called carbonic 

 oxide), which burns with a blue flame. 



Q. Why is the FLAME of a good fire YELLOW ? 



A. Because both the hydrogen and 

 carbon of the fuel are in a state of perfect 

 combustion. It is the white heat of the 

 carboy which gives the pale yellow tinge 

 to the flaming hydrogen. 



Q. What is LIGHT ? 



A. Rapid undulations of a fluid called 

 ether, striking on the eye. 



Q. How does COMBUSTION make these 

 undulations of LIGHT ? 



A. The atoms of matter (set in 

 motion by heat) striking against this 

 ether, produce undulations in it; as a 

 stone thrown into a stream, would pro- 

 duce undulations in the water. 



Q. How can UNDULATIONS of ether produce 

 LIGHT ? 



A. As sound is produced by undula- 



