100 



THE PRODUCTION AND USE OF HEAT 



continually by being carried into the furnace on the grate. 

 As the fresh coal approaches the zone of combustion, the 

 volatile matter is gradually distilled from the coal. There is 

 also provision for a supply of air ample to burn the volatile 

 matter as well as the fixed carbon or coke. 



FIG. 79. Mechanical stoker and a water-tube boiler. J5, Chain grate. 

 C, Fresh air. G, H, Baffle plates. * N, Water feed pipe. R, Blow off. S, 

 Steam dome. Y, Pressure gage. X, Safety valve. 



V. LIQUID FUELS 



113. The Burning of Liquid Fuels. The burning of kero- 

 sene and of gasoline has already been studied. It will be 

 remembered that, in each case, the liquid is first converted 

 into a vapor, and then the vapor is burned, using an adequate 

 supply of air. The same principle is used in burning liquid 

 fuels generally. Crude petroleum is burned by vaporizing 

 it by means of a jet of air or steam, after which the vapors are 

 burned in the proper supply of air. The gasoline in the 

 automobile is vaporized and mixed with the proper amount 



