310 Forestry Quarterly 



able a series of useful results from the experience with such 

 wood. 



Of oils, creosote products are the only ones which are used to 

 any great extent. Since the pure creosote was too high-priced, it 

 was mixed with an aqueous salt solution, chloride of zinc and 

 others. These processes had no important results whatsover. 

 In spite of the mixture the cost was very high. Moreover, the 

 durability was not increased to the extent anticipated. Today we 

 know, what at that time was to a considerable extent overlooked, 

 that in the mixing as at that time practised, one material inter- 

 fered with the penetration of the other and that the oil formed 

 scarcely more than an outer veneer. Now, if the solutions are 

 very weak, or if salts of slight efifectiveness are taken, it is nat- 

 urally, not to be wondered at if the treated wood does not have 

 any remarkable resistance. An oil treatment can bring economic 

 results only when the mine can produce the oil itself in its own 

 business as a by-product. 



Very many mines are satisfied with mere brush treatment of 

 the wood. This, however, is entirely non-efifective. Painted 

 wood lasts little longer than unpainted. It has been suggested 

 that the results would be more satisfactory if the wood were left 

 submerged in the oil for a longer time. It is, however, necessary 

 to warm the oil until the salt dissolves, since otherwise it does not 

 penetrate into the wood. A beginning of such dipping in creo- 

 sote (open tank method) has been made in German mines. 



Lastly we must mention the forcing in of oil, in cylinders, 

 under pressure. From the technical standpoint this is the best 

 method, since it alone ensures a true impregnation of the wood 

 and a really permanent protection. The best plant of this type 

 has been operated for many years by the Lothringen Mine in 

 Gehrte in Westphalia. This treatment costs $2.84 per hundred 

 cubic feet of wood. In comparison with this the Plesse manage- 

 ment had to pay $6.31 per hundred cubic feet for treatment by 

 the Riitgers works, and the Fuchs Mine as high as $8.52 in- 

 cluding freight. Without question, the life of wood is extra- 

 ordinarily lengthened by the treatment under pressure in cylin- 

 ders, while painting is entirely worthless and the results of dip- 

 ping (conducted according to the methods of Giussani and Krus- 

 kopf) are at least problematical. The economic value for mine 



