FENCING 229 



post into crude oil or in coal tar or to apply a coating of 

 either with a brush. This is not so satisfactory as the 

 other methods. 



The growth of the bacteria can be prevented by treat- 

 ment of the lower part of the post with zinc chloride, copper 

 sulphate, or bichloride of mercury. These solutions are 

 cheap, but they are soluble in water and have little value 

 if the posts are exposed to moisture. Heavy oils of coal 

 tar and petroleum are not affected by moisture, and are 

 poisonous to the fungi. Most of these oils have as a basis 

 creosote, a by-product of coal, secured in the manufacture 

 of illuminating gas. On account of its cheapness and the 

 ease with which it can be secured, creosote is considered 

 the most effective solution for the treatment of posts. The 

 method of using it is to set up one circular tank 3^ feet in 

 diameter and 3^ feet deep and a rectangular tank 4 by 4 

 by 8 feet in dimensions. The oil in the circular tank is 

 heated to 220 Fahrenheit and that in the rectangular tank 

 to no°. The posts, which have been peeled and seasoned, 

 are set upright, butt* down, in the hotter oil and left for a 

 time, depending on the species of wood. They are then 

 submerged in the cooler oil for another period, after which 

 they are taken out and piled to dry. The seasoning of the 

 wood removes the water, and the peeling saves the oil 

 which would be taken up by the bark. The bath in the 

 hotter oil drives out much of the air, so that the cooler oil 

 is drawn into the wood as the air which still remains con- 

 tracts. Oak, cottonwood, willow, and pine take this treat- 

 ment very readily. Basswood, maple, and birch receive 

 only a slight penetration. All species treated are of equal 

 durability. The cost of the treatment in 19 13 was from 

 10 to 15 cents, and a post made of wood which would cost 

 8 cents could be made to have a life of twenty years at a 

 total cost of 20 cents if treated at a cost of 12 cents. 



Setting wood posts. Posts should be selected which will 

 last as long as the wire which is placed upon them, as the full 



