FORESTRY. 675 



Notes on wood preserving, J. S. Thompson (Amer. Inventor, 12 (1904), No. 22, 

 pp. 476, 477). — A discussion is given of the theory of wood preserving. The method 

 of treatment of timber is largely determined by the use to which the timber is put. 

 Most processes in preserving timber may be classed under two groups, those depend- 

 ing on the injection of solutions of metallic salts and those relying on the hydrocarbon 

 oils. 



For the first the salts of mercury, copper, and zinc have been most extensively 

 used. While the salts of all three metals protect timber against both animal and 

 vegetable attacks, they are subject to the disadvantage of being soluble in water, and 

 treated timber which is subject to the action of or immersed in water will after a 

 time have the protective salts removed. In order to overcome this difficulty it has 

 been proposed to render the salt insoluble by electrolysis, or to inject a second salt, 

 which would form an insoluble compound with the other metal. 



The second method of treatment depends on the injection of hydrocarbon oils, 

 and for this purpose those obtained from the distillation of wood, coal, or petroleum 

 have given the best results. Of the coal-tar products, creosote is preferred, and its 

 action is held by different authorities to lie due to different properties. By some, 

 naphthalene, which occurs in the creosote, is claimed to be the preservative agent, 

 acting by filling the pores of the wood and by repelling attacks of animals by its 

 strong odor. Timbers examined after from 14 to 23 years of exposure have been 

 found to retain little or no naphthalene. 



Others consider the preservative action due to the phenolic bodies present in 

 creosote oil, but these can not be found present after 15 years' exposure. The third 

 class of bodies present in creosote are of an alkaloidal nature, the best known of 

 which is acridene. These bodies are claimed by a number of investigators to have 

 strong antiseptic properties, and although present to the extent of only about 2 per 

 cent in ordinary creosote, their presence in treated timber can be detected after 29 

 years' exposure. 



Based upon these conclusions, the author believes it possible to formulate an ideal 

 process for the preservation of timber, which would consist of careful seasoning and 

 then impregnating with a mixture of some solid hydrocarbons and alkaloidal bodies, 

 dissolved in some of the more volatile hydrocarbons. 



Railroads and the cross-tie question (Tradesman, 52 (1904), No. 5, p. 74). — An 

 account is given of the experiments being carried on by the Santa Fe Railway for the 

 testing and preserving of railroad ties. Stations have been located by the railway in 

 Texas, New Mexico, and Arizona, where ties are chemically treated with preserva- 

 tives. The experiments so far have been carried out along lines of cheap and efficient 

 methods of creosoting the ties, but up to the present time no practical method has 

 been discovered. 



At present the treatment employed is that of injection with zinc chlorid. This 

 treatment materially lengthens the life of the tie, which varies with the climate in 

 which it is used. Railway ties will last from 11 to 12 years in the dry atmosphere 

 of New Mexico, while in portions of Texas where there is a heavy rainfall the use- 

 fulness of a tie is ended in 4 or 5 years. 



In Texas the principal source of railway ties is the Texas pine, while on the Pacific 

 coast and eastward for some distance Oregon fir is most extensively used. 



Experiments are being carried on with a form of plate to protect the tie against 

 abrasion by the rail, and one made of hard wood grown in Australia has so far proved 

 very satisfactory. It has been found cheaper than the iron plates in use on many 

 railways and is almost as serviceable. 



