Fuel

is made of all sorts of materials, from dried,., dung, to hydrogen gas, and its heating power is measured by the * unit ' or amount required to raise 1 lb. of water 1 F. The 4 calorific * power of fuel therefore represents the number of lbs. of water which can be raised 1? F. in temperature by the combustion of 1 lb. of the particular F. and it varies very greatly, dry wood having only; 7353 units, alcohol 12,330, coke 12,800, ordinary gas 21.344. and hydrogen 62,031. Consequently, wood is only used in countries which have little or no coal, c.g. Sweden. bom