COST OF FENCING IN NORTH CENTRAL STATES. 23 



Service of the United States Department of Agriculture and by 

 various State experiment stations, with a view to determining the 

 best preservative materials and the effect of the treatment of post 

 timbers with them. It has been found that creosote, a by-product in 

 the manufacture of coal tar, is the cheapest and most efficient pre- 

 servative, and that naturally short-lived timbers treated with it will 

 withstand decay as long as the most durable woods. 



In many localities there is an abundant supply of cheap timber 

 which in its natural state is of little value for fence posts, but which 

 may be treated with a preservative so that its life will be greatly 

 prolonged. 



The treatment is very simple, and can easily be done on the farm. 

 The equipment necessary for the work is not expensive, but depends 

 to some extent on the number of posts to be treated and the amount 

 of time available for this work. If it is the intention to treat a few 

 posts at a time, only one tank will be needed. 



The posts that are to be treated should be thoroughly seasoned 

 and the bark should be removed from them so that the preservative 

 will be able to penetrate into them. A good time of the year to cut 

 them is in the spring after the buds begin to swell. They will peel 

 very readily at this time, and should season in time for treatment 

 in the late summer or early fall. After the posts are cut and peeled 

 it is well to place them in piles so that the air will circulate through 

 them, but so that they will not season so rapidly as to check. 



The method of treatment depends somewhat on the number of 

 posts that are to be treated and the time available for this work. 

 The posts are first placed in a tank of creosote which has been heated 

 to a temperature of about 220° F. They are left in this tank until 

 the creosote has penetrated through the sapwood of the post. The 

 time required to accomplish this depends upon the kind of timber 

 being treated. Soft woods will be more readily penetrated and 

 absorb more creosote. When the post has been in the hot creosote 

 the desired length of time it is then placed in a cold creosote bath, 

 where it should be left for several hours. While in the hot creosote 

 the fibers of the wood expand and force out the air and moisture 

 present. When placed in the cold creosote they contract and form 

 a partial vacuum, thus drawing a quantity of the preservative into 

 the wood cells. If only a limited number of posts are to be treated, 

 or if it is not necessary to complete the work in a short time, the 

 posts may be left in the tank of hot creosote until alter it has cooled. 

 If tliis method is employed, at the most, only two batches may be 

 treated in a day. II' many posts are to be treated, it is necessary to 

 have an additional tank for cold creosote. The posts may be taken 

 1V< in the tank of hoi creosote and immediately dipped in the cold. 

 This permits a continuous process to be carried on. 



