(•.70 ANTISKITIC JJtEATMKNT OF TIMHER. 



Owintr, however, to the injury done to timber by drying it artificially 

 at temperatures up to 250° F., the action of stoves in closed cham- 

 bers, or of superheated steam, is very prejudicial ; he therefore con- 

 siders 230° F. as the limit of safety for heating timber intended for 

 engincoiing purposes. Boulton has therefore patented a process 

 depending on the different boiling points of water (212° F.) and of 

 heavy tar-oils (350° F. to 700' F.) ; the creosote is admitted at a 

 tempemture slightly over 212° F. and the action of the air-pump 

 contiiniod, so that any water in the logs is converted into steam and 

 drawn off by the air-pump through a condensing worm in a dome on 

 the top of the injecting cylinder. The creosote is still liquid at 

 212° F. and rejdaccs the water in the log, which is not then subject 

 to any excessive heat and consequently its tissues arc uninjured. 

 Boulton also maintains that in the case of railway-sleepers to be used 

 in India and other hot countries, this injecting at a temperature of 

 212* F. fills all cracks in the wood with creosote ; as in India there- 

 fure the sleepers will not be subjected to &uch a heat in the ballast, 

 they will not crack an}' further there, which is not the case with 

 sleepers injected at a heat less than that they may experience in 

 Indian baliast.— Th.] 



"When heavy tar-oil is used for injecting purposes, the wood is 

 coloured dark black ; the hard, pitchy components of the tar 

 form a crust almost as hard as stone on the surface and fill all 

 the crevices of the wood. [In England about 50 gallons of 

 heavy tar-oil are used per load of 50 cubic feet, the oil weighing 

 11 lbs. per gallon. — Tr.] 



F. Lowenfeld has designed a portable apparatus for injecting 

 wood, which is based on the principle of first steaming the wood 

 and then injecting it by forcing-pumps in chambers deprived of air. 

 There are six of these chambers, which can be successively con- 

 nected with the steam-generator and in which the process of 

 injecting is carried on continuously, the sixth chamber being 

 removed and charged with wood, the first chamber steamed, and 

 so on. 



In Blythc's system (according to Gayer) the wood is first 

 artificially dried and then placed in boilers, where it is sub- 

 jected to a high pressure of steam containing heavy oil of creosote 

 in suspension. The wood is subjected to injection from G to 

 20 hours, and is completely injected, assuming a dark colour like 



