1 62 CALORIFIC POWER OF FUELS. 



The same result can be reached more quickly by taking 

 the ratio of the specific heats to the volume (Table VIII). 



N 8125X0.306 = 0.249 



CO 2 1308 X 0.426 = 0.055 



CO 0083 X 0.306 = 0.002 



0484 X 0.310 = 0.015 



i.oooo 0.321 



0.321 X 130 X 8.938 = 372 calories. 



This may be still further simplified in practical work with 

 the combustion under normal conditions. Base the calcula- 

 tion on the proportion of carbonic acid, using 0.306 as coeffi- 

 cient for the remaining gases. Then 



C = (0.4261;+ o.io6R)(T-t] 



v CO, 0.1308 X 0.426 = 0.055 



R N, CO, and 0.8692 X 0.306 = 0.266 



0.321 



By means of the coefficients in Table IX we can still 

 further shorten the calculation. By this table we get directly 



0.321 X 130 X 8.938 = 372 calories. 



The loss of heat due to temperature of the waste gases 

 varies according to the condition of the boiler, its surface for 

 radiation, the grate surface, and the air supply. With the 

 most advantageous cases, and moderate combustion, the gas 

 temperature at the exit does not exceed 150 (302 F.), and 

 the loss, 5 or 6 per cent of the total heat of combustion. 

 It may reach 10 per cent, and in some cases even more. 



2. HEAT OF THE HYGROSCOPIC AND COMBUSTION WATER. 



During combustion, coal furnishes a quantity of aqueous 

 vapor from its hygroscopic water and its hydrogen ; the latter 



