GASEOUS FUELS. IOI 



hydrogen coal than we have taken, and the decomposition of 

 the fuel in the body of the furnace with a certain quantity of 

 aqueous vapor formed during the combustion, or from the 

 moisture in the air supplied. 



Mahler determined the heat of combustion of a sample of 

 gas from the Follembray glass-house, and found its composi 

 tion per volume, using coal from Bethune, to be : 



Marsh gas 2 



Hydrogen 12 



Carbonic oxide 21 



Carbonic acid 5 



Nitrogen 60 



100 

 The heat of combustion calculated from its composition is: 



Marsh gas 0.02 X 10038= 200.8 



Hydrogen O.I2X 3091= 370.9 



CO 0.2 1 X 3043 = 639.0 



1210.7 

 With the bomb he found 1212 calories. 



WATER GAS AND MIXED GAS. 



Water gas is produced when water is decomposed at high 

 temperatures by fuels containing but little hydrogen, such 

 as anthracite, charcoal, or coke. Mixed with hydrocarbon 

 vapors, added to enrich it, or which may have been decom- 

 posed with the aqueous vapor, it serves for the illumination 

 of a great number of cities, principally in America. But this 

 is not its only use, as it is used for heating, and also for gas- 

 engines. Mixed with producer gas, it has become a powerful 

 means of heating, especially where high temperatures are 

 wanted. 



Water gas contains but little nitrogen : this is its main 

 distinction from producer gas, and that which gives it a 

 special value from an economical heating point of view. 



