166 



CALORIFIC POWER OF FUELS. 



The loss, then, is 1238.7 in 8000, or 15.48 per cent. 



If instead of knowing the proportion of the hydrocarbons 

 we know only that of carbon and hydrogen, the heat values 

 calculate separately. Then, instead of methane o. I, there 

 would be carbon 0.05, and hydrogen 0.2. Then the cal- 

 culation. would be 



0.2 X 0.089 = 0.0178; 

 0.05 X 1.073 = 0.0536; 

 o.i X 1.251 = 0.1251 ; 



0.0178x34500= 614.1 

 0.0536 X 8137 = 436.1 

 0.1251 X 2435 = 305.0 



1355.2 calories 



The difference, 1355.2 1238.7 = 116.5 calories, or 0.9 

 per cent of the calories lost, or 15.48 X .009 = 0.138 per cent 

 of the total calories of the coal, which is small compared with 

 other sources of error. 



By employing Table VII we may dispense with reducing 

 the volumes to weights, thus : 



Hydrogen 



Carbon vapor. . 

 Carbonic oxide 



o.2m 3 X 3091 = 

 0.05 X 8722 = 

 o. i X 343 = 



618 



436 

 304 



1358 



The preceding is an exaggerated case; as usually, with 

 ordinary working, the loss is from 2 to 7 per cent, rarely 

 exceeding the latter. Either method of calculation may be 

 used, then, without risk of causing an error of importance. 



4. CALORIES DUE TO THE SOOT. 



The soot in smoke consists of carbon with a trace of 

 hydrogen. It can be calculated as all carbon without appre- 

 ciable error and with the coefficient 8137. Knowing the 

 volume of gases produced by I kilogram and its content in 

 black (page 154), calculate the number of calories. Under 



