THE RAPID AGEING AND FIREPROOFING OF WOOD. 291 



XXXV. The Iiapid Ageiny and Fireproojiny of Wood.^ 



The preservation of wood was formerly accomplished by drying 

 and covering it with coatings designed to prevent the entrance of 

 air and moisture. But these have now given place to numerous 

 plans for the introduction of antiseptic liquids. 



The decomposition of wood commences soon after it has been 

 felled and exposed, whether in logs or pieces, to the air, to 

 moisture and to vai-iations of temperature. It is also destroyed 

 by being buried in the ground. Cut up into planks, and dried in 

 the open air, it warps and cracks, causing considerable reduction 

 in its value. At 300° C. (572" Fahr.) all wood, dry or pre- 

 served by antiseptics, is carbonised without production of flame ; 

 but if subjected to a red heat or to the action of a burning body, 

 as in fire, the pieces of wood are completely destroyed, even if 

 they are covered with a coating opposing a certain resistance to 

 the fire. Whence the multitude of processes made use of for 

 more than a century for increasing the durability of wood. 



Not only are the chemical and physiological causes of the 

 changes of wood now understood, but a remedy has been found 

 for the evil. It has been known for a long time that dry wood is 

 much less subject to decomposition than moist wood, which is still 

 impregnated with sap. This knowledge has led to submitting the 

 wood before use either to natural or to artificial and rapid 

 desiccation. 



Until within the last few years the first or natural method, the 

 most simple, that of exposure to the air for a time, aflfbrded good 

 results ; but natural drying, which occupies a good deal of time, 

 especially for hard species and for considerable thicknesses, 

 necessitates a very large surface for piling the wood, and the loss 

 by waste due to splits at the extremities increases the cost of dry 

 wood. This explains the numberless methods employed for 

 securing the rapid drying of the wood under the best possible 

 conditions. 



Paulet describes one hundred and seventy-three methods, most 

 of which have been patented, and which may be distributed in the 

 three following groups : — 



1. By natural infiltration or displacement, applicable to stand- 

 ing wood or to that) recently cut down. 



^ Condensed from the translation of an article from the Revue de Ohemie 

 Iitdustriellc, printed in the Scientific American and the IndAan Forester. 



