GASEOUS FUELS. 



is less calorific by volume than the other hydrocarbons occur- 

 ring in illuminating gas. 



111 



A cubic metre of hydrogen develops 3091 calories 

 burning; a cubic metre of marsh gas develops 10038 calories; 

 a cubic metre of olefiant gas, 15250 calories. 



GAS OF GASOGENES. 



The gasogenes, instead of transforming the fuel into car- 

 bonic acid and water in a single combustion, produce this 

 change in two distinct burnings, the first being to make a 

 combustible gas and the second to burn this gas with air. 



In the first furnace, the coal, for example, is burnt in such 

 a manner by feeding with an insufficient supply of air that a 

 gaseous mixture is produced, containing principally carbonic 

 oxide, besides nitrogen from the air. As the combustion has 

 been well or poorly managed, it contains a less or greater 

 quantity of carbonic acid, the production of which is avoided 

 as much as possible. This is done by giving to the fuel only 

 just enough air to form carbonic oxide, and not enough to 

 form carbonic acid, even partially, and by making the bed of 

 fuel quite deep. 



The heat produced by this combustion is not used, and 

 consequently an important part of the calories of the coal is 

 lost, Gasogene gas is then lower in calories, and inferior to 

 coal gas, as commonly made by distillation. 



