PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION, 515 



changes the wood admits of at ordinary temperature before it is 

 used. Any organic matter that is subjected to a low temperature 

 for a while will have the equilibrium of its affinities disturbed. 

 This is eiFectually accomplished in a plan devised by him, viz : 

 By distilling the wood until all the changes in the chemical 

 constitution of the wood, are brought about, which occur at 

 ordinary temperatures. This result is partially attained by kiln- 

 drying it in a heat of 180", as is done with wood used in the 

 manufacture of pianos, melodeons, &c. The third process is by 

 using chemical reagents to act upon the more unstable organic 

 compounds and convert them into more stable substances. The 

 fourth process is by partially fossilizing the wood — filling the 

 pores with some inorganic matter, and leaving it in a mineral 

 state in the pores of the wood. In building he found it necessary 

 to use wood that had been exposed to every vicissitude of tempe- 

 rature, during at least one season after being squared. The 

 principal object to be obtained is to keep out the water. Fossi- 

 lizing, kyanising, &c., were so expensive that they had to be aban- 

 doned. The most economical plan is to steep wood well in run- 

 ning water to wash out the sap, and then to pile it up so that 

 the air could pass freely through it, and the heat of the sun and 

 weather may act upon it, 



Mr, Veeder did not think coal tar was a preservative for wood. 

 He stated that he had his house shingled in 1840 with perfectly 

 dried shingles, and they are perfectly sound now. Sometime 

 later he built an addition to his house, and when shingling it he 

 had a man to cover them with coal tar ; those shingles are now 

 rotten and will have to be removed. There are on his ground 

 several stumps of trees, the history of the cutting down which 

 has passed away. The ground where they now stand was for- 

 merly wet ground. 



Chairman. — What kind of wood is it ? 



Mr, Veeder. — Yellow pine. In planting posts he was in favor 

 of using a covering of asphalte, but should be laid on when the 

 timber is perfectly seasoned, 



Mr. Seely said that Mr. Hedrick was right when he said that 

 if we remove the odor we remove creosote ; coal tar is offensive 

 to ever)^ one. What we mean by creosote here is that portion 

 of the coal tar which contains the most creosote. Coal tar has 

 a remarkable penetrating power. Take two pieces of timber, 



