REID — ON THE ECONOMY OF TIMBER. 33 1 



When creosote which prevents decay in all albuminoid substances 

 was discovered in tar, the idea at once presented itself of using this 

 means, either as crude tar from wood, or from coal, which is simi- 

 lar, or their products. This is by far the best method yet known to 

 prevent decay. The tar cannot be made to permeate the wood, 

 and when applied externally it prevents moisture from escaping, 

 and in so far favors decay ; hence its use has been abandoned. A 

 crude, cheap, liquid creosote is obtained from tar by distillation, 

 which can be made to permeate timber, and has remarkable preser- 

 vative powers. It is now the substance most extensively used in 

 England for this purpose. 



If we could thoroughly permeate timber with creosote, tar, resin 

 of any kind, soap, paint, or oil, we can preserve the wood thus 

 acted on, but it is rendered more inflammable, and under any cir- 

 cumstances is costly. 



Many metallic salts when forced into wood, preserve it from 

 decay, and render it less inflammable. The most active agents are 

 Corrosive Sublimate, Sir Wm. Burnett's Chloride of Zinc, 

 Sulphate of Copper, JByrolignite of Iron and JPhosphate of 

 Baryta; but their cost greatly excludes their use. Sulphate of 

 Iron is cheaper, but of less value. 



Common Salt has great preservative power, and is much used 

 in shipbuilding, and might be much more used with good eflect to 

 ward ofl" decay. 



There are three ways of using these substances : 



1st. — Applied to the surface which is of little use. 



2nd. — A French Process of making a hole in the tree, and in- 

 troducing the substance in solution. By this method before the 

 tree dies the salt will thoroughly permeate it, and while preserving 

 the timber, will, with some salts stain it very beautifully. The 

 objection to this, apart from cost, is its impracticability on a large 

 scale where lumbering is carried on. 



3rd. — Placing the wood in large strong vats and forcing the 

 solution into it. This is the most available method. 



J^reserving from Fire, — In this country this result would be 

 even preferable to protection from decay., but the means which con- 

 fers the former does the latter as well. 



