COST OF FEITCING IN NOETH 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 after it has cooled. 
If this method is employed, at the most, only two batches may be 
treated in a day. If many posts are to be treated, it is necessary to 
have an additional tank for cold creosote. The posts may be taken 
from the tank of hot creosote and immediately dipped in the cold. 
This permits a continuous process to be carried on. 
