FORESTRY AND CONSERVATION 401 



treated, or 0.6 gallon per post if the top also is impregnated. The 

 best treatment is that which will give, with a reasonable absorption, 

 the deepest possible penetration of the oil into the wood in the 

 shortest time. 



Woods which are naturally durable in contact with the ground, 

 such as cedar, locust, white oak, and black walnut, were also 

 included in the experiments. In general, a heavy treatment is re- 

 quired to impregnate their sapwoods, and their heartwoods can 

 not be successfully treated. Though preservative treatment some- 

 what prolongs the life of these species, they are not only too expen- 

 sive to be treated with economy, but even without treatment they 

 are likely to cost more than cheaper and equally satisfactory posts 

 that can be had by creosoting an inferior wood. 



In California, posts of different species of eucalyptus were creo- 

 soted. A three-hour bath in hot oil was a sufficient treatment for 

 green posts, but the oil penetrated very irregularly. When the posts 

 were inverted after butt treatment, the free oil followed the large 

 ducts in the wood and appeared on the top of the post. A few tests 

 also were made on quaking aspen, boxelder, Douglas spruce, and 

 silver maple. Quaking aspen will probably require a treatment 

 similar to that recommended for cottonwood. The heartwood of 

 Douglas spruce is impenetrable by open-tank treatments, but the 

 sapwood may be easily impregnated. Boxelder and silver maple 

 absorb creosote readily, but the penetration at the ground line is 

 relatively small. Therefore, whenever a choice of species is possible, 

 only the woods best adapted to preservative treatment should be 

 used. 



The procedure in treating may be summarized as follows: (1) 

 Raise the temperature of the hot bath to 220 F. before putting the 

 posts in the tank. Maintain this temperature throughout the path. 

 Have sufficient oil in the tank to submerge the butts 6 inches higher 

 than the ground line when the posts are set. (2) If only one tank 

 is used, the oil will be absorbed by the posts during the cooling bath, 

 and more should be added to keep them submerged to the proper 

 depth. (3) If two tanks are used, liquefy the cold bath by heating. 

 The best temperature is from 100 to 120 F. Transfer the posts 

 from the hot to the cold bath as quickly as possible. At least that 

 portion of the post which has been heated should be immersed 

 quickly in the cold bath. 



Cost of Treatment. General cost figures are valueless, but the 

 cost under any specified conditions may be readily ascertained. 

 Apparatus and oil are the two most important items of expense. 

 The charge per post for the apparatus should not exceed 1 cent 

 when a serviceable outfit is used and its permanency is considered. 

 Labor and fuel charges are usually ignored in fence-post treatments, 

 and hence are omitted in the examples of cost given below. If, 

 however, it is desired to include them, the number of posts treated 

 daily is important. Of course the size of the post affects the cost. 



The cost of creosote by the barrel varies widely according to 

 locality. In the Eastern States it costs 12 to 15 cents per gallon; 



