520 AUXILIARY FOREST INDUSTRIES. 



the wood was frequently boiled in antiseptic liquids, steam 

 being introduced into the vessel in which the wood was 

 immersed until the liquid in it boiled. Blue vitriol, borax 

 solution, etc., were thus injected, but the liquid must be kept 

 at the boiling point for 10 or 12 hours. 



Kecently H. Liebau, in Magdeburg, has attempted to intro- 

 duce the liquid from the interior of the pieces of wood instead 

 of externally, in order to protect the heartwood from decay. 

 This method can be used only for stakes, piles, etc., the axis of 

 which is bored through after they have been driven into the 

 ground, and tar-oil, pitch, etc., poured into the cavity. Nothing 

 as yet can be said regarding the efficacy of this method. 



[Boppe states * that in France, mining pit-props are immersed 

 for about 24 hours in solutions of 1J Ibs. per gallon (150 gr. 

 to 1 liter) of sulphate of iron, or in wood-tar heated to a tem- 

 perature of 278 F. (140 C.), in order to render them more 

 durable. It is found that -if the immersion is continued for 

 a longer period, the wood becomes brittle, and that chloride 

 of zinc, blue vitriol or creosote poisons the wood and renders 

 it dangerous to the miners. Tr.] 



Another plan is to place telegraph-posts in a glazed, burned 

 clay tube filled with sand and tar; or cement and tar are 

 poured round the base of the wood in the ground. 



W. Powell, of 6, Stanley Place, Liverpool, noticed that 

 dry rot never occurs in the wood used in sugar-refineries, 

 and in 1903 invented a process in which timber is saturated 

 with a solution of sugar, and then the moisture evaporated 

 rapidly by stoving at a high temperature. The process requires 

 2 or 3 days only. Powell finds that this processed timber 

 cannot be infected with dry rot. He experimented with 

 paving blocks, 3 inches by 5 inches by 9 inches, of red pine, 

 poplar, beech and red-gum, and found that the}^ gained 

 respectively 1 lb., 5 Ibs., 4 Ibs. and ^ lb., their original 

 weights being 4 Ibs. 12 ozs., 4 Ibs. 11 ozs., 7 Ibs. 7 ozs., and 

 8 Ibs. 13 ozs. 



As regards absorption of water, beech in a natural 

 state absorbs 1 pint of water per block, but processed beech 



* " Technologic Forestiere," p. !7, 



