THE TIMBERS OF COMMERCE 



*' A tree attaining a height of 70 to even 100 ft. by 24 inches in 

 diam." (49). Splits with great difficulty. 



Authorities. Nordlinger (86), vol. vii. p. 52. Hough (49), vol. 

 iii. p. 25. Sargent (100), No. 184. Wiesner (131), L. 12, p. 991. 



Colour. " Heart-wood dark or nearly black, only developed in 

 very old specimens" (100). Sap-wood whitish-brown: brown: grey: 

 usually with a cast of grey or greyish-green in irregular patches. 

 " Very thick, upwards of 100 rings" (49). This sap-wood is the 

 wood commonly met with in commerce. 



Anatomical Characters. Transverse section : — 



Pores. Readily visible in the pore-ring, rather fine, size 4, 

 very variable : scattered uniformly or rather more numerous in 

 the Spring wood in wide rings : few, 7-25 per mm. : here and 

 there united in short radial lines of 2-5 pores together : appear 

 light against the dark ground. 



Rays. Just visible, fine, size 5, uniform : long, tapering very 

 gradually : very numerous about 12 per mm. : direct but running 

 round the larger pores : very little denser than the ground. 



Rings. Clear on account of a coarser-pored Spring zone : 

 contour well-rounded. 



Soft-tissue. Obscurely and narrowly encircling the pores and in 

 exceedingly fine, close, continuous, concentric lines, like fine shad- 

 ing at right-angles to the rays. 



Pith. Yellowish, about 1 mm. wide. 



Radial Section. Usually much lighter in shade than the trans, 

 sec. Apparently coarser in grain owing to the pores being often 

 exposed in parallel pairs, darker than the ground : rays visible 

 in certain lights as minute flakes : rings only indicated by the 

 recurring bands of pores : soft-tissue abundant in excessively 

 fine vertical, whitish lines (lens). 



Tangential Section. As the Radial, but the pore-bands appear 

 finer and the Rays are indistinguishable with lens (need micro.). 

 The rings are more or less vague loops and the soft-tissue runs 

 in horizontal waved lines. 



Type specimens from commercial sources and also authenti- 

 cated by Hough. 



No. 131. MARBLE EBONY (Madagascar) Dios- 



pyros sp. 

 Plate X. Fig. 85. 

 Natural Order. Ebenacese. 



Physical Characters, etc. Recorded dry-weight 49 lbs. per cu. ft. 

 Hardness Grade 3, compare Blackthorn. Smell none: taste 

 slightly astringent. Burns well and quietly : embers glow 

 brightly in still air : no resin expelled by heat. Solution with 



150 



