FUEL 



493 



heating 75 pounds of water from the freezing to the boiling point ; but when it has 

 been for some time exposed to the air, it contains at least 10 per cent, of water, which 

 is partially decomposed in the combustion into carburctted hydrogen, which causes 

 flame, whereas pure dry charcoal emits none. 



Winkler gives the following as the results obtained by him with charcoal from 



various sources : 



Charcoal from : 



Poundsof water heated 

 from to 100 Cent, 

 by 1 pound of charcoal 



Air required by per- 

 fect combustion 



Pounds of lead reduced 

 by 1 pound of charcoal 



Poplar . 



Sycamore 



Fir 



Ash 



Birch 



Oak 



Elm 



Willow 



Pine 



On an average 

 757. 



On an average 



293-5 cubic feet 



at 19 Cent. 



33-56 

 33-23 

 33-51 

 33-23 

 33-71 

 33-74 

 33-26 

 33-49 

 33-53 



A cubic foot of charcoal from soft wood weighs upon an average from 8 to 9 pounds, 

 and from hard wood 12 to 13 pounds; and hence the latter is best adapted to main- 

 tain a high heat in a small compass. The radiating heat from charcoal fires consti- 

 tutes one -third of the whole emitted. See CHARCOAL. 



The following Table gives the approximate values of given weights of wood. 



According to Landet, 'Polyt. Centr. 1854,' the value of fuel bought by volume cor- 

 responds to the product of the absolute heating power of fuel into the weight of a cer- 

 tain volume. 



These two factors have the following value with various kinds of fuel : 



Kind of Fuel 



Holm oak (wood in large pieces or logs) . . 10,000 



Bed beech (logs) 9,941 



Oak, both varieties in mixture (logs) . . . 9,763 



White beech (logs) 9,490 



Oak (logs) 9,448 



White beech (pieces and stumps in mixture) . 9,392 



Birch (logs) 9,260 



Birch (pieces and stumps, &c., in mixture) . . 9,224 



Birch (stumps) 8,836 



Pine (stumps) . 8,587 



Oak (both varieties in mixture) .... 8,342 



Eed beech (stumps) 8,214 



Alder (log-wood) 8,127 



Alder (pieces and stumps in mixture) . . . 8,070 



White beech (stumps) 8,030 



Red beech (branches) 7,953 



Pine (branches) 7,898 



Alder (stumps) . . .. . , 'v 7,849 



Pine (stumps) , - . , 7,808 



Pine (branches) 7,752 



White beech (branches) 7,644 



Pine (logs) 7,624 



Willow (pieces and stumps in mixture) . - , 7,584 



Birch (branches) 7,473 



Willow (branches) 7,344 



Aspen (pieces and stumps) 7,290 



Oak (both varieties in mixture) .... 7,288 



Pine (logs) 7,064 



Charcoal 7,000 



Turf dried at 100 C 4,800 



Turf containing 20 per cent, of water . . . 3,600 



Turf charcoal 5,800 



Mineral coal of a medium quality . . . 7,500 



Do., containing 15 per cent, of ash . . . 6,000 



Wood dried at 100 C 3,600 



Absolute heating 

 power 



Weight of 1 cubk 

 metre in kilos. 



380 

 380 

 371 

 370 

 359 

 338 

 381 

 332 

 318 

 312 

 317 

 314 

 293 

 291 

 313 

 304 

 287 

 283 

 283 

 281 

 298 

 377 

 285 

 269 

 276 

 273 

 277 

 256 



