Report of Missouri Farmers' Week. 493 



75 cents per gallon in barrels of 52 gallons. 

 80 cents per gallon in barrels of 34 gallons. 

 80 cents per gallon in barrels of 25 gallons. 

 85 cents per gallon in kegs of 15 gallons. 

 90 cents per gallon, in kegs of 10 gallons. 

 $1.00 per gallon in kegs of 5 gallons. 

 Sample gallon cans $1.25 f. o. b. Milwaukee. 

 There is one other method, which, in spite of its first high 

 cost, is perhaps the best and most economical in the long run. 

 This is the so-called "open tank" process, using creosote as the 

 preservative. Creosote is a distillate heavier than water and is 

 obtained by the distillation of tar or a tar-like substance. There 

 are several kinds of creosote, depending on the kind of tar distilled. 

 Among them are: 



1. Coal-tar creosote. This is derived from coal tar which is 

 produced by the destructive distillation of bituminous coal at 

 temperatures of 1,500° to 3,000° Fahrenheit. It is a by-product 

 in the manufacture of coke and gas. 



2. Oil-tar creosote is derived from oil tar. Oil tar may be 

 obtained by the destructive distillation of petroleum in a gas 

 retort where oil gas is the main product and tar the by-product. 

 It may also be obtained from the manufacture of water gas. 



3. Wood-tar creosote comes from the distillation of wood tar. 

 Wood is destructively distilled leaving a residue of charcoal. Gases, 

 vapor and a liquid distillate are carried over. From this liquid 

 distillate may be obtained crude tar. 



4. Mixed creosotes are produced by mixing some other sub- 

 stance with creosote or by mixing tars of different sources. 



The general process of obtaining creosote from the tars is 

 practically the same. The tar is distilled in a metal retort, the 

 vaporjs collected and condensed. Those distillates which are 

 heavier than water form the creosote. The temperatures at which 

 they are obtained vary greatly, but are usually between 200° and 

 360° centigrade, depending upon the character of the residue de- 

 sired. The chief differences in creosotes is in the character of the 

 hydrocarbons, whether they belong to the paraffin or aromatic 

 series. 



Posts to be treated by the "open-tank" process are immersed 

 to a depth of about 30 inches in creosote which is held in some 

 form of a tank with an arrangement for heating. Heat expands 

 the air and water in the posts. As the preservative cools there is 



