48 PROPERTIES OF WOOD. 



fungi, hence the natural scent of a wood is a proof of its 

 soundness ; when decay sets in, the odour given off is either 

 very disagreeable, or the opposite. 



The scent of certain woods renders them commercially 

 valuable, especially as a strong scent keeps off insects and 

 renders the timber more durable. Pencil-cedarwood (Juni- 

 perus virgmiana, J. bermudiana and J. chinensis), owing to its 

 pleasant scent and fine grain, is preferred for pencils. Cedrela- 

 wood from Cuba and Central America is used for cigar-boxes 

 on account of its fine scent and lightness. Indian sandalwood 

 (Santalum album] preserves its strong, agreeable scent for years. 

 Violet-wood (Acacia homolophylla, from Eastern Australia), 

 when used for parquet-flooring, as in the castle of Herren- 

 chiensee, emits a fine violet-scent. 



Teak, olivewood, pulley- wood (Guaiacum), Buxus and Sam- 

 bucus emit a strong odour of caoutchouc. Some woods, such as 

 freshly cut stinkwood from South Africa (Ocotea bullata), have 

 a disgusting odour. Mathey adds that of Gustavia tetrapetala 

 from Guiana. 



4. Hardness. 



As wood is not homogeneous, it offers a resistance to its 

 penetration by tools, that differs according to the direction of 

 the penetrating force. Hence its hardness depends on the 

 following : 



1. Direction of the force. The greatest resistance is 

 offered to forces acting across the wood-fibres ; the least 

 resistance is along the fibres and also in the planes of the 

 medullary rays, that is in the radial direction, so that wood 

 is most easily split radially. 



2. Use of implements. Nails, knives, axes, saws, augers, 

 planes, etc., act so differently that the same wood exhibits 

 various degress of hardness to the different implements. It is 

 however true that hard wood is always more difficult to deal 

 with than soft wood. 



3. The degree of wetness of the wood. All woods have 

 greater tenacity and looser texture when they are wet. In 

 hard woods, this looseness of texture is more important than 

 the tenacity produced by wetting, so that hard woods are more, 



