PLYIMOUTM INSTITUTION. 231 



that had been dug out of the turf beds. The change which the 

 moss and herbage undergoes in forming turf was shewn, by its 

 solubility in cold solution of soda. It had become, in great part, 

 the substance known to chemists by the* name " Ulmine." 



Turf was stated to burn slowly, with a low even heat; and to be 

 particularly suited for processes requiring heat of that character ; 

 the lecturer suggested the establishment of a small pottery on 

 the moor, where good clay is found as well as turf. 



Turf might also be used for purposes requiring stronger heat; 

 by reducing it to charcoal ; which is nearly as good as wood 

 charcoal. He found, good dry Dartmoor turf yield 33 per cent, 

 of charcoal, on the small scale ; but of this 9 or 10 was ashes ; 

 leaving 23 or 24 per cent, of pure charcoal. In France, where 

 they use turf charcoal about the iron mines, they get 40 per cent. ; 

 but this is on the large scale; and the ashes are probably more 

 than in Dartmoor turf. 



He thought turf charcoal might be employed in the blowing 

 houses of the tin works; and that it would answer most of the 

 purposes of wood charcoal, with a little contrivance to dispose of 

 the ashes. 



He then passed to wood, stating that, when fresh hewn, it con- 

 tained 40 to 50 per cent, of water ; of which, one half dried 

 away by exposure or stacking. Fire wood might, therefore, 

 contain about |- of its weight of water; and, beside this, upwards 

 of a third of its weight of the elements of water, united with 

 carbon. The carbon amounted to about 37 per cent.; and to 

 this only was owing the heat produced in the combustion of 

 wood. 



The heaviest woods were the most economical burning ; 

 because the flames from light wood carry off much of the heat 

 up the chimney. 



Wood contrasts particularly with turf; givhig the most rapid 

 and unsteady heat of any fuel employed. 



The mode of making charcoal was then described ; and the 

 produce stated to be from 17 to 28- per cent., according to the 

 method, and the skill of the workmen. Common oak charcoal 

 was described as a strong, quick fuel ; but much less quick than 

 the cliarcoal made for gunpowder; which is prepared from light 

 woods by slow heating, and comes out very light and porous, 

 takes fire quickly, and is very soon consumed. 



He would not suggest any new employment for charcoal, as 

 our wood was already burning away too fast; but would 

 recommend turf and lignite charcoal to be used in its stead. 



