70 THE REASON WHY. 



Lord, what is man that thou takest knowledge of him! or the son of man, 

 that thou makest account of him." PSALMS CXLIV. 



Because the melted grease runs down too rapidly, and at too low 

 a temperature to undergo combustion. It therefore reduces tka 

 Jieat, and extinguishes the flame. 



258. Why is it more difficult to blow out the flame of a 

 candle with a cotton ivick than one with a rush wick ? 



Because the cotton wick imbibes more of the combustible 

 materials, and holds in its loose texture the inijammable gases in a 

 state ready for combustion. 



259. Why does llowing sharply at a candle flame put it 

 out? 



Because the breath drives away the vapour of the grease which, 

 becoming gaseous, supports the flame. 



And because too rapid a flow of cold air reduces the temperature 

 below the point at which combustion can be maintained. 



260. Why will a gentle puff of breath, if given speedily 

 after the flame is extinguished, re-kindle it? 



Because the oxygen of the air combines with the carton and hydro- 

 gen that are still escaping from the heated wick, and re-lights it. 



261. Why will not a similar puff re-kindle the flame of 

 a rushlight? 



Because its wick retains but little heat, and holds a comparatively 

 small amount of combustible matter in a volatile state. 



262. Why is a flre, when it is very low, sometimes put 

 out by blowing it? 



Because the too rapid flow of cold air reduces the temperature of 

 the burning mass. 



263. Why will a piece of paper twisted like an 

 extinguisher put out a candle? 



Because, before the flame of the candle can ignite the paper, the 

 oxygen contained within it it consumed, and the flane i* 

 suffocated. 



