EXPANSION. 107 



Q. What are the SPAEKS OF FIRE, which 

 burst from the WOOD ? 



A, Very small pieces of wood red hot, 

 separated from the log by the force of the 

 air, as it bursts from its confinement. 



Q. Why does DEAL make more snapping than 

 any OTHER WOOD ? 



A. The pores of deal are very large, 

 and contain much more air than wood of 

 a closer grain. 



Q. Why does DRY WOOD mak&more SNAPPING 

 than GREEN WOOD ? 



A. In green wood the pores are filled 

 with sap, and therefore contain very little 

 air ; but in dry wood the sap is dried up, 

 and the pores are filled with air instead. 



Q. Winy does DRY wood BURN more easily 

 than GREEN or wet wood ? 



A. Because the pores of dry wood 

 are filled with air, which supports com- 

 bustiorf; but the pores of green or wet 

 wood are filled with vapour, which 

 extinguishes flame. 



Q. Why does VAPOUR EXTINGUISH FLAME ? 

 1st Because the coat of water (which 

 wraps the fuel round) prevents the 



