104- 



PROPEETIES OF WOOD. 



The wholesale destruction of most woods in hot countries by termites, or 

 white ants, is well known, and the number of woody species in India which 

 resist their attacks is very limited. Even deodar wood, in spite of the oil 

 with which it is saturate 1, is sometimes attacked by them, and the sapwood 

 of every wood is eaten away very rapidly. The heartwood of sal (fthnrca 

 i-olmxttt}, teak, tun (_Cedrela Too /M), ebony, sissu (/A///V/V//V/ Sissoo') and some 

 other hard woods resist their attacks, but in the case of building-timber it is 

 always best to saturate it with r/y/r/V/^-oil, extracted from Dipterocarpw 



Fig. 43A. The Teredo. (After Boppe). 



turlinatus. Engineeis in India should be careful to erect or- ly solid masonry- 

 walls, and not leave crevices in them up which the white ants may ascend to 

 the roof of a building ; also they may mix arsenic with their mortar with 

 advantage. 



It has often been suggested that softer woods if injected with creosote, 

 sulphate of iron or zinc, or corrosive sublimate (bichloride of mercury), would 

 be found to resist the attacks of white ants, but no serious attempts have as 

 yet been made in India to utilise injected wood. Termites occur everywhere 

 in India, up to altitudes of about 4,000 feet above sea-level. 



Fig. 44. Borings of the Teredo. (After Boppe). 



In order to preserve museum wood-specimens from insects, it is best to dip 

 them in a solution of one part of corrosive sublimate to twenty parts of water. 



Ethereal oils in woods, especially in those that are strongly scented, protect 

 them from insect-attacks, though the presence of resin is not always a 

 protection. 



Wood immersed in fresh-water is very durable, even beechwood lasting for 

 centuries. In the year 1858, twelve oak piles of the lloman bridge near Aargan 

 came to the surface, and the wood was hard enough to be made into toys. 



Wood used in sea-water at shipping ports and stores of wood kept under 

 water at these places, are subject to the attacks of ceitain animals. Some 



