550 AUXILIARY FOREST INDUSTRIES. 



Japanese charcoal (Quercus serrata) is 82*9 ; of beech char- 

 coal, 38*5 ; spruce, 31/5 ; boxwood, 81*7. Hassenfratz's 

 figures are too low. Good charcoal should be bluish black, 

 with an oily lustre ; it should not split, but have a conchoidal 

 fracture, should have a metallic ring when struck, and exhibit 

 clearly the structure of the wood. It should be hard and 

 without taste or colour, burn with a short, blue flame, without 

 smoke or odour, without crackling or emitting sparks. Good 

 charcoal is highly absorptive of gases ; beech charcoal absorbs 

 35 times its volume of C0 2 , 90 times its volume of ammonia. 

 Charcoal is antiseptic, it prevents a mouldy scent and hinders 

 decomposition ; it has an immense durability. 



SECTION III. THE COMBUSTION OF WOOD. 



As regards the utilisation of the combustion of wood 

 for heating purposes, this is dealt with in the next chapter on 

 the industrial uses of wood ; here, changes in the substance 

 of wood by combustion in order to obtain useful materials 

 from soot and ashes are considered. 



Lampblack is prepared cbiefly where there are supplies 

 of resinous conifers used for making turpentine and rosin. 

 The residue after making oil of turpentine and the resinous 

 roots of pines supply the raw material, which is burned with 

 admission of oxygen sufficient to maintain a weak, reddish, 

 smoky flame. The soot is collected from the smoke in 

 chambers covered internally with wool. Lampblack is 

 obtained also from coal-tar. 



Ashes, manure-ash and potash were obtained formerly, 

 when wood was without any value, by burning the wood 

 with complete exposure to the air. Such a practice is now 

 confined to remote forests only. But in modern artificial 

 forests there is still much unsaleable material from which 

 ashes may be obtained profitably. Branch-wood and top-and- 

 lop, the almost worthless materials from cleanings and early 

 thinnings, rotten wood and stump- wood attacked by fungi is best 

 burned, so that it may not increase danger to the forest from 

 insects, fungi and fires. The ashes thus obtained are rich in 

 potash, and when mixed with humus si*pply!splendid garden- 



