16S IXDrsTKTAL USES OF WOOD. 



jiossible, however, to obtain the best matciiiil, and wood of all 

 kinds is used for both i)urposes. 



Firewood is still emi)loyed in factories, which may be classified 

 according as they require hardwoods, as in soap-making, laundries, 

 and all factories employing boilers ; or softwoods, producing a 

 quickly radiating intense heat, as in bakeries, potteries, brick- 

 kilns, lime-kilns, &c ; finally charcoal, the heat of which is not 

 only quick and intense but also very enduring, as for the work 

 of locksmiths, blacksmiths, glass-makers, Sec. 



The carbonisation of wood is described in the third part of the 

 present work. [Charcoal of alder, dogwood, &c., is used in 



2. ComhuHtloii of Wood in order to produa' certain Snhstaiices 

 ichicJi are either Intermediate or llesidind. 



The intermediate substances are obtained during wood-car- 

 bonisation, as for instance pyroligneous acid, wood-gas, tar, 

 pitch, lamp-black, &c. ; the residual substances remain after 

 the wood has been more or less completely consumed, as for 

 instance potash, &c. 



The manufacture of pyroligneous acid, which is used to form 

 several chemical compounds, has in many places been undertaken 

 on a large scale. Woods which yield the best fuel are most 

 productive in this respect, and above all those of beech and birch. 

 A cord (216 cubic feet) of sound beechwood will yield 25 cwt. of 

 distilled products (tar, acetic acid, water, kv.), and 1^. 2 cwt. of 

 pyroligneous acid. 



Most illuminating gas is made from coal, but exceptionally 

 from strongly resinous red pinewood [in N. America from saw- 

 dust. — Tr.]. Wood-gas can be more easily and thoroughly 

 purified than coal-gas. Although tar is obtainable from all 

 kinds of wood, broad-leaved woods are less suited and far less 

 productive than conifers. Eed pine and spruce are chiefly em- 

 l)loyed. In the north of Europe, in some forests, the whole 

 stem of these trees is thus utilized, and the trees are stripped 

 standing of all their bark, except a small strip in order to en- 

 hance the flow of turpentine. In other forests, where timber is 

 more valuable, only pine-roots arc thus utilized, and these only 

 rarely, as coal-tar has almost driven wood-tar out of the market. 



