WOODY FIBRE. 361 



their property of entering into fermentation, putre- 

 faction, or decay.* 



But the decay of woody fibre is very much accel- 

 erated by contact with alkalies or alkaline earths ; 

 for these enable substances to absorb oxygen, which 

 do not possess this power themselves ; alcohol, 

 gallic acid, tannin, the vegetable coloring matters, 

 and several other substances, are thus affected by 

 them. Acids produce quite an opposite eflfect ; they 

 greatly retard decay. 



Heavy soils, consisting of loam, retain longest the 

 most important condition for the decay of the vege- 

 table matter contained in them, viz., water ; but 

 their impermeable nature prevents contact with the 

 air. 



In moist sandy soils, particularly such as are com- 

 posed of a mixture of sand and carbonate of lime, 

 decay proceeds very quickly, it being aided by the 

 presence of the slightly alkaline lime. 



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 hydrogen 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 C^% ff^, 0^^, the 22 equiv- 

 alents of oxygen, with 11 equivalents of carbon, and 

 22 equivalents of hydrogen, which are supposed to 

 be oxidized 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 carbon, which must remain 

 unchanged, since carbon does not combine with 

 oxygen at common temperatures. 



But this final result is never attained in the decay 

 of wood under common circumstances ; and for this 

 reason, that with the increase of the proportion of 



* See an account of the process for *' kyanizing" timber in the Farm- 

 er's Register, Vol. III. p. 368. 



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