98 CALORIFIC POWER OF FUELS. 



One kilogram of carbon burnt to carbonic oxide disen- 

 gages 2489 calories, while I kilogram of carbon burnt to car- 

 bonic acid generates 8137 calories. There is lost, then, in 

 burning carbon to carbonic oxide in a gasogene about 30 per 

 cent of the available calories. 



At first sight this method of working seems irrational, but 

 for obtaining high temperatures there are practical advantages, 

 whose importance far exceeds the loss of heat in the gaso- 

 gene. It permits much more elevated temperatures, and the 

 recovery of a large portion of the heat, which in direct sys- 

 tems of heating in high temperature furnaces passes to the 

 chimney as complete loss. There is actually an economy in 

 the ordinary metallurgical methods even with this loss. 



By means of gasogenes, we produce three kinds of gaseous 

 fuel : the gas called producer or air gas, formed by the incom- 

 plete combustion of the fuel, with production of a mixed gas 

 containing carbonic oxide and hydrogen compounds ; the gas 

 called water gas> from the decomposition of water by carbon at a 

 high temperature, with production of carbonic oxide, hydrogen, 

 and hydrogen compounds; and the gas called mixed gas, 

 from the mixture of the two preceding ones by a process 

 which combines the production of the two gases in the same 

 furnace. 



PRODUCER OR AIR GAS. 



We have said that air gas results from incomplete com- 

 bustion, and that its formation causes a loss of one third of 

 the calories resulting from the complete combustion of the 

 fuel. These gases contain, naturally, the nitrogen of the air 

 used, to which must be added that of the air necessary to 

 change the carbonic oxide and the hydrogen to carbonic acid 

 and water. 



The heat of combustion and the composition determined 

 ' ^. by different experimenters varies considerably, showing that 

 v hey did not always work with average samples. 



