CREOSOTING. 305 



this with creosote and heat it, to a little over 212 F. (to 

 evaporate the water still in the wood) ; then keep it at that heat 

 for about 24 hours (or more, according to size of wood), run off 

 the hot oil, and take out the creosoted wood when cool enough 

 to handle. For such purposes, an open oblong iron tank or 

 boiler and a furnace cost about .60. Beech and Scots Pine 

 absorb the oil most readily, and Spruce and Larch least 

 readily ; while softwoods and Conifers generally absorb 

 more readily than hardwoods. Scots Pine and softwoods 

 take easily about 8 to 9 Ibs., and even up to 10 to 11 Ibs. 

 (1 gallon) of creosote per square foot ; but neither Oak 

 nor Larch, the most durable woods without treatment, absorb 

 the oil well. Creosoted Beech fence-stobs last twenty years, 

 while untreated Beech only lasts about three years. In the case 

 of Scots Pine stobs, long immersion is a waste of creosote, as it 

 runs o.ut again on the stobs being stacked after treatment. As 

 absorption is not uniform, the cost of creosoting varies both 

 with the kind and the quality of the wood ; but with creosote 

 at 2Jd. a gallon, creosoting on the average usually comes to 

 about 4d. per cubic foot, or Id. per fence-stob 4j ft. x 3 in. x 

 3 in., and 9d. per 100 lineal foot of paling rails 4 x 1 in. (though 

 ranging up to 6d. and Is. 3d. respectively). 



When creosoting large quantities of wood, railway sleepers, &c., 

 in closed iron cylinders with injection under pressure, the 

 timber is packed as closely as possible, the air extracted by an 

 air-pump, and creosote heated to 1 20 F. run in ; and when full, 

 a force-pump is used to gradually produce whatever pressure is 

 desired (usually 100 to 120 lb., but sometimes more), until a 

 gauge attached to the creosote tank shows that absorption has 

 ceased. Softwoods can thus be made to absorb 10 to 12 Ibs. of 

 oil per cubic foot. At Welbeck a pressure-cylinder 30 ft. long 

 by 4| ft. diameter with self-contained pumps, which cost about 

 300 and is worked by a 2^ horse-power portable engine, takes 

 a charge of 450 cubic feet of small converted timber (gates, 



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