402 HORTICULTURE, FORESTRY, FLORICULTURE 



on the Pacific coast, 15 to 20 cents ; in certain localities in the Rocky 

 Mountain region it is as high as 30 cents. In the table the absorp- 

 tion of oil per post is stated for the recommended treatment. To 

 this must be added a certain quantity of oil which evaporates from 

 the hot bath. The amount of creosote which evaporates depends 

 mainly upon the grade used, but 20 per cent of the absorption is 

 accepted as the average. The quantity of oil consumed per post is, 

 therefore, one and one-fifth times the absorption. 



Value of Treatment. In portions of Maryland locust posts 

 cost 35 cents a piece, and are difficult to obtain even at this price. 

 A pine post, treated in the manner recommended will doubtless 

 equal one of locust in durability, and will cost only half as much. 

 In the prairie region of Minnesota willow posts of sufficient size to 

 last fifteen years cost 25 cents. Creosoted cottonwood posts could 

 be substituted for these, and would be considerably cheaper as well 

 as more durable. In sections of Idaho lodgepole pine posts are 

 extensively used. The following illustrates the annual saving af- 

 fected by creosoting such posts: 



In general, it may be said that any post properly creosoted will 

 last twenty years. To determine the exact length of life under va- 

 rious conditions, posts experimentally treated are being tested in 

 fences, and detail maps on which each post is numbered are made to 

 record the kind of post and its treatment. By means of such maps 

 it is possible to study the durability of the individual posts and the 

 effects of various treatments under different conditions. 



^ Prolonging the Life of Shingles. Wood used on the farm in 

 various forms other than post material may often be advantageously 

 preserved from decay by chemical treatment. The results obtained 

 assuredly justify the cost of treating all timbers used in foundations, 

 sills, beams, and planking, as well as the lower portions of board 

 fences, and the lumber used near the ground in sheds and barns. 

 The treatment of these is very similar to that given posts. Shingles, 

 however, form an important special class of material. 



With the grades of shingles obtainable nowadays exposure to 

 rain and sun commonly results in warping or curling. Water ab- 

 sorbed during a storm subsequently evaporates rapidly from the 

 upper surface and rather slowly from the lower surface. Conse- 

 quently, the upper part of the shingle shrinks more than does the 



