ELISHA MITCHELL SCIENTIFIC SOCIETY. 31 



The process of creosoting is carried out according to this gen- 

 eral plan. Good, '^saj)" or porous pine Ininher, with or with- 

 out previous charring, is run into the cylinder on a truck and made 

 fast in position by the screws outside. Th<- ends are then sealed 

 perfectly and the temperature raised gradually by su[>erheated 

 steam to al)out 550° F., the suction pumj) is applied and as near a 

 c()m[dete vacuum as possible produced and sustained for about 14 

 hours. This treatment serves to (]vy the wood thoroughly and 

 expands its pores to the fullest extent, leaving them em})tv for 

 the entrance of the fluid. The suction pump is disconnected then 

 and sufficient oil to fill the cylinders run in. The force pump is 

 next applied, with a pressure as high as 120 pounds per cubic 

 foot, which is sustained until the desired anjount of oil has beeii 

 injected. This is very easily calculated by knowing the capacity 

 of the cylinder less the charge of lumber and the cubic measure of 

 lumber, and as much more oil over the amount necessary to fill 

 <;ylinder as lias been consumed represents the amount injected 

 into wood. The oil stands at about 400° F., and the tempera- 

 ture of the cylinder is reduced to that degree. The oil being 

 injected, the surplus is withdrawn to tanks, the lumber run out 

 and is ready for shipment, the entire process usually requiring 

 about 24 hours. 



Many circumstances modify this general plan. It is by the 

 condition of timber that the time of drying is determined — 

 whether it is very green or seasoned; small planks or large tim- 

 bers; and as to duration of creosotijig, whether small planks or 

 large timbers, very porous or compact, and to the amount of oil 

 <lesired injected. Upon the careful manipulation of this process 

 <lepends the success of its product, and every precaution is taken 

 to insure it. The timbers may or may not be previously charred. 

 Any quantity of oil from 3 to 20 pounds per cubic foot may be 

 injected, and any size timbers handled from 1 to 20 inches in 

 diameter and up to 100 feet long. 



Previous charring is recommended as increasing the absorbing 

 power by at least 50 per cent. Twelve pounds of oil per cubic 

 foot is considered sufficient in all ordinary circumstances — more 



