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CHAPTEE IV. 



THE SEASONING AND PRESERVATION OF TIMBER. 



THE larger the proportion of nitrogenous or albuminoid 

 substances contained in any kind of wood, the more likely it 

 is to be attacked by insects and saprophytic fungi, which are 

 the chief causes of decay, and whose attacks are facilitated 

 when timber is exposed to rapid alternation of dampness and 

 dryness, especially if combined with warmth. If the albumen 

 can be sterilised or so altered as to be made unfit for the food 

 of insects and fungi, the woody fibres then become strongly 

 protected against both of these destructive agencies, and also 

 against the action, thus obviated, of dissolving ferments de- 

 veloping under their operation. Some kinds of timber, and 

 notably hardwoods as compared with softwoods, and very 

 resinous as compared with only slightly resinous Conifers, have 

 more or less of natural protection from substances contained in 

 their tissue (e.g., tannic acid in Oak, strong resinification in 

 Larch and Pine, &c.) ; but all timber is much more durable if 

 utilised in dry and airy places, or if entirely submerged in 

 water, or buried in the ground where atmospheric oxygen is cut 

 off and there are practically no alternating changes from wet to 

 dry. The weight of a piece of wood gives of itself no reliable 

 indication of its durability e.g., Beech used, say, for fencing 

 decays much sooner than Larch ; but for any one particular 

 kind of wood (Oak, Ash, Beech, Larch, Pine, Spruce, &c.), the 



