106 ANSWERS TO PRACTICAL QUESTION'S 



that the H burns first, and thus heats up to the lumi- 

 nous point the particles of C as they float outward to 

 the air, causes the illuminating power of the hydro- 

 carbons. 



28. Is there a gain or a loss of weight by combustion ? 



The products of combustion weigh as much as the fuel 

 and the O which enters into combination with it. 



29. Why does snuffing a candle brighten the flame ? 



Because it removes the charred wick, which diminishes 

 the heat of the flame both by conduction and radiation. 



30. Why is the flame of a candle red or yellow ', and that 

 of a kerosene oil-lamp white ? 



(See Philosophy, page 225.) 



The heat of a candle-flame is much less than that of 

 kerosene, and thus the colors characteristic of a lower 

 temperature are produced. 



31. Why does blowing on a light extinguish it? 



Because it lowers the temperature of the flame below 

 the point of union between O and C. 



32. Why will water put out afire? 



(See Chemistry, page 93.) 



Partly by absorbing the heat of the fire, and partly by 

 shutting out the O. 



33. What should we do if a person's clothes take fire t 



The best course is to wrap the person in a blanket, 

 carpet, coat, or even in his own garments. This smothers 

 the fire by shutting out the O. 



