In order to arrive at the money value of the various fuels heretofore
described a method of composition has been arrived at which gives
very accurately their comparative worth. The rule is too advanced for
this elementary work, but the following results are plainly to be
understood, and will be found to be of value.
Lbs. of Fuel. Temperature of Water 212°
Coal, 14.62 lbs of Water.
Coke, 14.02 „
Wood, 8.07 „
Wood; 25% of water, 6.05 „
Wood Charcoal, 13.13 „
Peat, perfectly dry, 10.30 „
Peat, with 25% moisture, 7.41 „
Peat, Charcoal (dry), 12.76 „
Tan, dry, 6.31 „
Tan, 30% moisture, 4.44 „
Petroleum, 20.33 „
Coal gas 1 lb. or (31-1/3 cub. feet) 47.51 „
The way to read this table is as follows: “one lb. coal has an average
evaporative capacity of 14.62 lbs. of water,” or
One lb. of peat with one-quarter moisture will evaporate, if _all_ the
heat is utilized 7.41 lbs. of water.
In practice but little over half of these results are attained, but for
a matter of comparison of the value of one kind of fuel with another
the figures are of great value; a boiler burning wood or tan needs to
be much larger than one burning petroleum oil.