164 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



how different preservations keep out and destroy destructive 

 germs. 



The fresh sapwood of white pine is 50 per cent, water 

 (of which 60 per cent, is sap, 35 per cent, is in the cell walls, 

 and 5 per cent, is in the cell contents). The heart-wood 

 contains a much smaller percentage of water, but what is 

 there is sealed in so that it is difficult to eliminate. Preliminary 

 soaking in water accelerates the rate of air-drying by removing 

 much gum and mineral matter. Though the primary objects 

 of seasoning are to cut down the food supply of decay fungi 

 and render the wood more receptive to preservative chemicals, 

 the reduction in weight is an important consideration from the 

 point of view of freight costs. 



Very careful temperature control is necessary with kiln drying, 

 and the dried timber should be impregnated at once, to prevent 

 reabsorption of moisture. 



A prolonged series of measurements by the United States 

 Forest Service shows that the external circumference of poles 

 is practically unaffected by seasoning, even where there is 

 heavy checking. 



Oil paint protects a smooth dry pole against decay, but the 

 paint is easily broken through, and does more harm than good 

 to imperfectly seasoned poles by entrapping moisture. Tar 

 gives a more elastic coating and some antiseptic effect, but 

 the penetration is poor, and internal decay occurs almost as 

 badly as with oil paint. Concrete sheathing is costly but 

 effective, apparently owing to absorption of salts from the green 

 concrete. Charring is uncertain in action, weakens the pole, 

 and increases the fire risk. 



There are two groups of antiseptics, viz. mineral salts and 

 oils. The great disadvantage of the mineral antiseptics is that 

 they are soluble in water and are quickly leached out. The 

 author discusses the characteristics of creosotes from other 

 sources than coal tar, and describes the high pressure " full 

 cell" and the "empty cell" methods of applying preservative. 

 A table is given comparing standard specifications for various 

 creosotes. Notes are included on the methods and special 

 features of all other preservative treatments now in common 

 use. 



Methods are described for repairing poles already decayed 

 at the ground line. Whether the old pole is repaired or a new 



