292 THAXSACTIOXS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



2. By pressure in the open air, applicable to wood in its bark ; 

 or by pressure in an enclosure, applicable to dry wood. 



3. By superficial application of antiseptic agents (by carbonisa- 

 tion, immersion and coating), applicable to all kinds of wood. 



In the first group may be mentioned rafting, which consists in 

 immersing the pieces in water. This allows of drying the wood 

 more rapidly ; for the sap having been partially driven out by the 

 water, which has replaced it, the latter will evaporate more 

 readily than the sap. For instance, oak for flooring, which would 

 require two years of drying in the open air, may be dried in four 

 months after having been subjected to the action of the water. 

 Wood is immersed in a stream or basin for three or four months. 

 If the circumstances allow of raising the temperature of the 

 water to 30° C. (86° Fahr.), the time of immersion may be 

 reduced to fifteen or twenty days. 



Steam also afforded good results so far as the drying is con- 

 cerned, but unfortunately the fibre is affected to some extent and 

 the wood becomes much less tenacious. In the Leclerc process the 

 operation is conducted by steam, followed by drying in a current 

 of warm air. The wood is arranged in a close chamber of 

 masonry, and the steam is brought in for forty-eight hours by 

 perforated pipes. Under the action of the condensed water a part 

 of the sap comes from the cells of the wood, and the other part is 

 coagulated. Thus the result is not complete. The wood is 

 afterwards dried by causing a current of warm air (30°-35° C. = 

 86°-95° Fahr.) to circulate in the same chamber for a fortnight 

 in the case of planks of ordinary thickness. The wood is piled 

 upon the open-work floor of the chambei-, inclining it sufiiciently 

 to cause the sap to flow. Each piece is sejjarated from its 

 neighbours, and this allows the air and steam to circulate freely 

 over the whole surface. For drying, the warm air is introduced, 

 at one time from above, at another from below, and alternately 

 at one or the other extremity of the chamber. It is drawn in 

 through the wood and drawn out by a ventilator working at the 

 opposite extremity. 



Boucherie's processes, which belong to the first and second 

 groups, utilise at one time the vital osmatic force of growing 

 trees ; at another they effect the infiltration of a liquid, or the 

 displacement of the sap by this liquid, on the tree recently felled. 

 In the first case, one or two saw cuts are made at the base of the 

 trunk, or several deep holes are drilled into it. An earthen band, 



