366 Traksactioks of the American Institute. 



•would savo this country $4,000,000 every year in railroad ties and 

 $50;000,000 in fencing and fvijm buildings. 



There are two situations, and only two, in which wood is not 

 attacked by decay ; where sound, well seasoned timber is kept per- 

 fectly dry, and where it is kept constantly immersed in water. The 

 timbers in the roof of Westminister Hall are known to be 450 years 

 old. The car\nngs on the stairs are 300 years old. Some of the inte- 

 rior of the Basilica at Rome has not been renewed for 1,000 years. 

 The piles of old London bridge are still soimd, though sunk in the mud 

 of the Thames 800 years ago. There stands in the altar of the old brick 

 church at Wetherby a table made from the oak of the first structure 

 for worship in the place. The trees furnishing this timber must have 

 been cut 230 years ago. But nineteen-twentieths of the timber 

 in constant use is subjected to alternations of moisture. When 

 those alternations are extreme, and no care is taken to preserve 

 the wood, with most kinds of timber rot begins in from three to five 

 years. A few instances are known iii which ^'ellow locust, red cedar 

 and mulberry have lasted as gate posts or in fences fifty years. From 

 inquiries of a great number of farmers, I think the average duration 

 of fence posts in this country is about fifteen years, and of rails about 

 twenty years. The aim of inventors has been to develop a process 

 for preserving ship timbers and wood used for manufacturing purpo- 

 ses. It is certain that no process can be of practical value to the 

 former which is nice or complicated or expensive. Hence the mode 

 by forcing copperas and zinc in solution into the pores of w'ood, 

 granting that it is effectual, will never benefit the farmer. 



Why Wood Decays. 

 • Wood is mainly made up of woody fibre, and a substance full of 

 nitrogen. The fibre is of itself able to resist decay for a long time. 

 But the nitrogenous matter is as liable to decay as cheese or the 

 white of an egg. Hence the first thing to be done is to dry up, or 

 to fix, or to expel, or to stiffen this nitrogenous matter so the air and 

 water will act upon it slowly or not at all. If wood is first soaked 

 in water and then thoroughly dried jt is found to last much longer. 

 Why is this? Because tlie decaying substances are partially dis- 

 solved in the water and soaked away. Drying afterwards carries off 

 the water, and if moisture can then be kept from it decay will 

 be greatly retarded. If the water in which wood is immersed is kept 

 boiling fur some time, this substance is stiffened like the white of a 



