84 OF WOOD IN GENERAL. 



air-drying or steaming will obviate this. Various temperatures 

 are employed in kiln-drying ; but it is stated that at 100 to 

 120 F., Oak, Ash, and other hardwoods can be seasoned in dry 

 kilns without any of the loss of strength often alleged to result 

 from artificial heat. Poplar planks are dried in kilns in America 

 at 158 F. to 180 F. ; but Oak, Ash, Maple, Birch, Sycamore, etc., 

 are first air-seasoned for three to six months, and are then exposed 

 to these temperatures for six to ten days for 1-inch stuff. Pine, 

 Spruce, Cypress, and Cedar of the same dimensions are dried for 

 four days immediately after being felled and sawn up. Such 

 temperatures are more than sufficient to kill and prevent fungus 

 growth, and the fact that well-ventilated seasoned wood is seldom 

 attacked shows that the amount of moisture then left in the wood 

 is insufficient to support fungus growth. Walnut gun stocks are 

 desiccated in the rough by a current of air at 90 or 100 F., pass- 

 ing over them at such a rate as to change the whole volume of air 

 every three minutes, and it is found possible in this way to save a 

 year of seasoning. Temperatures of 250-300 F. are almost 

 certainly detrimental to the wood. Such desiccated timber must 

 not be exposed to damp before being used or it will re-absorb 

 moisture, and coloured woods are said to lose colour and lustre 

 under this treatment. 



Seasoning by passing the smoke-laden products of combustion 

 from the furnace through the timber pile has been found success- 

 ful, and has an important preservative effect. A modification of 

 this, known as M'Neile's process, consists in exposing the wood to 

 a moderate heat in a moist atmosphere charged with the products 

 of the combustion of fuel. 



Boiling timber in water has much the same effect as steaming, 

 but is costly, and probably weakening in its effects. 



Seasoning by immersion in water is a slow method that answers 

 well for wood to be used in water or in damp situations. It 

 reduces warping, but renders the wood brittle and less elastic. 

 It is important that the submergence be total, as otherwise there 

 is great danger of fungus attack along the water-line. Two or 

 three weeks' water-seasoning is often a good preparation for air- 



