A. Yes.
15. Q. About how many cubic feet of air is necessary for the combustion of a pound of coal in a locomotive fire-box?
A. About 300 cubic feet of air must pass through the grates and fire for complete combustion of one pound of coal.
16. Q. Why must air be heated before combining with coal?
A. Air, like coal and its gases, must be heated before they will unite to form what is known as combustion and so as not to reduce the temperature of the fire-box below the igniting point of the gases.
17. Q. Why is it necessary to provide for combustion a supply of air through the fuel in the furnace?
A. In order to supply the oxygen necessary for combustion.
18. Q. What is the effect upon combustion if too little air is supplied? If too much air is supplied?
A. If too little air is supplied, combustion is not complete, and only one-third as much heat is obtained. If too much air is supplied, combustion is complete; but the excess air must be heated, resulting in a lower temperature. If twice the amount of air required for complete combustion be supplied, the temperature of the fire-box will be about one-half as high.
19. Q. Give a practical definition of the igniting temperature.