PHILIPPINE FIREWOOD. 



Table V. — Ultimate composition of different dry woods — Continued. 



Kind of wood. 



Carbon. Hydr°- 



Oxigen. 



Nitrogen. 



Ash. 



Available 

 calories. 



Main 

 calories. 



From GottUebA^ 



Oak 



Ash 



Hornbeam 



Beech: 



130 years old 



100 years old 



60 years old 



Birch 



Fir 



Spruce 



Per cent. Per cent. 

 50.22 5.99 



49.77 



6.26 



49.48 



6.17 



49.03 



6.06 



48.87 



6.14 



49.14 



6.16 



48.88 



6.06 



50.36 



5.92 



50.31 



6.20 



Per cent. 

 43.42 

 43.37 



43.77 



44.36 

 44.29 

 44.07 

 44.67 

 43.39 

 43.08 



Pa- cent. 

 0.09 

 0.07 

 0.06 



0.11 

 0.06 

 0.09 

 0.10 

 0.05 

 0.04 



Per ct. 

 0.28 

 0.53 

 0.52 



0.44 

 0.64 

 0.54 

 0.29 

 0.28 

 0.37 



4,600 

 4,710 

 4,730 



4,790 

 4,770 

 4,760 

 4,770 

 5, 025 

 5,080 



The chemical composition of wood is very complex, as the material con- 

 sists of both organic and inorganic bodies. The former are made up 

 chiefly of cellulose and lignin which are more or less united with each 

 other, together with the soluble and insoluble constituents of the dried 

 sap, such as sugar, dextrin, starch, fibrin, albumin or other nitrogen- 

 containing bodies, and often more or less tannin, dyes and different kinds 

 of resin. The relative amounts of these present in different woods, or 

 different parts of the same tree, vary or may vary with the age, condition 

 of the growth and physiological processes that have taken place, the soil 

 and physical conditions upon which and under which it is grown, the 

 time of the year, etc. However, the fact remains that the principal 

 compounds of all woods are the same, and those substances present in 

 smaller quantities contain the same elements — carbon and hydrogen. It 

 is the amount of carbon and the amount of hydrogen in excess of the 

 equivalent amount of oxygen which determines the calorific value. 



In general, the theoretical heating' value of a fuel, i. e., the amount of 

 heat produced by completely converting the carbon into dioxide and the 

 hydrogen into water, Avithout regard to the efficiency of the furnace in 

 which it is consumed, may be calculated from its elementar}^ analysis. 

 The difference in the way that the carbon, hydrogen and oxygen are 

 combined in the wood has no influence on the heating effect. The cal- 

 culation concerns only their percentages. The greater part of the hydro- 

 gen is left in the form of water by the breaking down of the complex 

 compounds and has no heating effect. 



From the analysis of wood it might be expected that the calorific value 

 of that part remaining after deducting the water and ash would be almost 



"Journ. f. prakt. Chem. N. F. (1883), 28, 385; J. B. (1886), 31, 355. 



