100 CALORIFIC POWER OF FUELS. 



grams carbon produce 2100 grams carbonic oxide, requiring 

 1 200 grams oxygen. 1200 grams oxygen occupy 839 litres. 

 50 grams hydrogen produce 450 grams water, and require 

 400 grams oxygen. These 400 grams oxygen occupy 279 

 litres. But the coal itself contains 50 grams oxygen, occupy- 

 ing 35 litres. 



We have, then, 839 + 279 35 = 1083 litres of oxygen 

 required, and to calculate the amount of air needed multiply 

 by 4.77. This gives 5163 litres of air needed for the incom- 

 plete combustion of I kilogram of carbon. These 5163 litres 

 contain 4080 litres of nitrogen. 



To obtain the total volume of gases produced by the 

 incomplete combustion, we may add to the volume of the air 

 introduced the volume due to the formation of carbonic oxide, 

 and this is equal to the volume of the oxygen used, or 839 

 litres. We have, then, 5163 + 839 = 6002 litres. But a 

 quantity of oxygen has disappeared corresponding to the 

 formation of the water, or 279 35 244 litres (35 litres 

 exists in the coal as above), and 6002 244 =5758 litres of 

 gas produced by the incomplete combustion of I kilogram of 

 coal. 



Now, then, 5163 litres of air contain 4079 litres of nitro- 



gen, which would form - -?, or 70.8 per cent of the total 



gas. All these numbers are at o and 760 mm. pressure.* 



Generally gasogenes contain less nitrogen, different causes 

 producing diminution, among which are the use of a lower 



*One pound of coal would be 6300 grains carbon, 350 grains oxygen, 

 and 350 grains hydrogen; 0.90 Ib. carbon produces 2.1 Ibs. carbonic oxide, 

 and needs 1.2 Ibs. oxygen; 1.2 Ibs. oxygen occupies 13.44 cu. ft.; 0.050 Ib. 

 hydrogen produces 0.450 Ib. water, and needs 0.400 Ib. oxygen, or 4.48 cu. 

 ft. The 0.05 Ib. of oxygen in the coal occupies 0.56 cu. ft. Then 13.44-+- 

 4.480.56 = 17.36 of oxygen required 17.36X4.77 = 82.81 cu. ft. of air, 

 containing 65.41 cu. ft. nitrogen. Total gases, 82.81 -f- 13.44 ~ 39 2 = 9 2 -33 

 total volume of gas, and 



65 41 



= 70.8 per cent. 

 92-33 



