OF WOODY FIBRE. 313 



Now let us consider the decay of woody fibre 

 during a very long period of time, and suppose 

 that its cause is the gradual removal of the hydro- 

 gen in the form of water, and the separation of its 

 oxygen in that of carbonic acid. It is evident that 

 if we subtract from the formula C36, H22, O22, 

 the 22 equivalents of oxygen, with 11 equivalents 

 of carbon, and 22 equivalents of hydrogen, which 

 are supposed to be oxidised by the oxygen of the 

 air, and separated in the form of water ; then from 

 1 atom of oak wood, 25 atoms of pure carbon will 

 remain as the final product of the decay. In other 

 words, 100 parts of oak, which contain 52*5 parts 

 of carbon, will leave as a residue 37 parts of car- 

 bon, which must remain unchanged, since carbon 

 does not combine with oxygen at common tempera- 

 tures. 



But this final result is never attained in the de- 

 cay of wood under common circumstances ; and for 

 this reason, that with the increase of the proportion 

 of carbon in the residual humus, as in all decomposi- 

 tions of this kind, its attraction for the hydrogen, 

 which still remains in combination, also increases, 

 until at length the affinity of oxygen for the hydro- 

 gen is equalled, by that of the carbon for the 

 same element. 



In proportion as the decay of woody fibre ad- 

 vances, its property of burning with flame, or in 

 other words, of developing carburetted hydrogen on 

 the application of heat, diminishes. Decayed wood 



