IN CHEMISTRY. 107 



34. Ought we to leave open the doors or windows of a 

 burning house ? 



(See Chemistry, page 93.) 



No. Open doors or windows will make draughts of air 

 to feed the flame. 



35. Why does a street gas-light burn blue on a windy 

 night ? Is the light then as intense ? The heat ? 



O is mingled with the flame in sufficient quantities to 

 burn the H and C simultaneously. Thereby the heat is 

 increased, but the light diminished. The principle is that 

 of Bunsen's burner. 



36. Why does not the lime burn in a calcium-light? 

 Lime is a burned body; its symbol is CaO. 



37. Why is a candle-flame tapering? 



(See Chemistry, page 88.) 



The currents of air rushing toward the flame from all 

 sides give it the conical form. 



38. Why does a draught of air cause a lamp to smoke ? 



It lowers the heat of the flame below the point of union 

 between C and O, and thus the C is precipitated. 



39. What makes the coal at the end of a candle-wick ? 



The wick at the edge of the flame comes in contact 

 with the O of the air, and therefore burns. 



40. Which is the hottest part of a flame? 



Toward the point of the cone, where the gaseous en- 

 velopes meet and make a solid flame. 



