250 The Farm Woodlot 



puts them beyond the farmer's reach. Only such simple 

 and inexpensive processes as have been found best suited 

 for use on the farm will be considered here. 



Preservative materials 



The most effective, cheapest and most easily secured 

 material according to the United States Forest Service is 

 creosote, dead oil of coal tar, a by-product of coke ovens 

 and gas factories. The higher the specific gravity, the 

 better the results obtained. The price varies from 10^ in 

 the East to 27 i in the Rocky Mountains, and 15^ on the 

 Pacific coast. Timbers treated with this material have 

 often had their length of service increased tenfold. 



Copper sulphate, zinc chloride, mercuric chloride, car- 

 bolineum and many patent solutions make more or less 

 inferior materials on account of cost, solubility or diffi- 

 culty in applying. 



There are three practical methods of applying the pre- 

 servative : painting it on with a brush ; dipping the 

 timbers in a tank of the preservative; or putting them 

 through what is known as the open-tank process. 



Brush method 



The advantage of the brush method is that it requires 

 no tank, and the application is consequently cheap. The 

 creosote should be kept at a maximum temperature of 

 150° F. especially if the weather is cold, for it quickly 

 solidifies at a low temperature. The hot liquid is spread 

 evenly on the thoroughly peeled and seasoned post with a 

 large brush. Great care should be taken to get it into all 

 the cracks. When the first coat has dried, the second 



