30 



radiation, give to charcoal its special value. Igniting wood for 

 charcoal in caverns is wasteful, through the great access of 

 air. 



By the method of carbonising wood in ovens, tar and other 

 volatile products can be secured. The wood chosen for coal, 

 intended for gunpowder, is chiefly that of willows, poplars, 

 alder and lime. It must be healthy, and is preferred from 

 young trees. Woods which contain a good deal of hygroscopic 

 salts such as that of elms, firs, oaks are not adapted for the 

 purpose. Extreme degrees of heat in producing coal for gun- 

 powder or blasting powder should be avoided, otherwise the 

 best wood will not serve the purpose, because the powder 

 would be less ready to ignite. The yield of this coal is 16 

 to 17-100ths from the wood. Local powder-mills are sure to 

 be established here, especially as sulphur is readily obtainable 

 from New Zealand. The increase of manufactures is also cer- 

 tain to augment the demand for wood and coal hereafter. 

 For many industrial purposes charcoal is far preferable to 

 fossil coal. Coals from various kinds of Victorian woods are 

 placed before you. 



It was my intention, while explaining the industrial resources 

 of the forest, to show also how tar, vinegar and spirits might 

 be obtained by heating wood in close vessels, at a temperature 

 of 300 to 350 centigr., under a process called dry distillation. 

 But I must reserve this subject for another occasion; for 

 however simple the procedure may be regarded, as far as the 

 actual performance of this artisan's work is concerned, yet the 

 chemic processes, which are active in this form of decomposi- 

 tion, are of the greatest complexity; they present, moreover, 

 according to the wood employed and according to the degree 

 of heat applied, some peculiarities, which as yet have not 

 been fully investigated, holding out hope for the discovery of 

 some new dyes and other educts. It will be scarcely credited 

 by most of this audience, that the paraffin, which now largely 

 enters into the material for the candles of our households, is 

 not only obtainable from bituminous slates, turf and fossil 

 coal, but is also produced by the heating of wood under 

 exclusion of air. This substance is furthermore a hydro- 

 carbon of great purity ; and its cheap preparation, along with 

 other substances from our native wood, may possibly become 

 a local source of immense wealth. For obtaining information 

 on the products from heated wood, and the various apparatus 

 employed in dry distillation, reference may be made to the 

 great work, Chemistry Applied to Arts and Manufactures, by 



