On the Rhode- Island Coal. 227 



poses where sulphureous or bituminous vapour would 

 be injurious, and where its tendency to caking or co- 

 hering would interrupt the current of air, and create 

 great irregularity in the temperature of the fire. 



In order, therefore, to deprive it of these volatile in- 

 gredients, it is first charred, and, by this means, con- 

 verted into coak, a substance resembling charcoal in 

 many of its properties, and in every respect nearly si- 

 milar to Rhode- Island coal. In this state, coak gives, 

 a veiy intense and durable heat, without flame, and is in 

 general use for blast or wind furnaces ; but it is much 

 less pure than charcoal; it requires a greater draft of 

 air, and is more apt to vitrify ; though, in one respect, 

 this, as well as Rhode-Island coal, is to be preferred, as 

 it bears the blast better, and, when urged by a strong 

 blast is not so easily blown away, nor does it consume 

 so rapidly. 



I have thus given a short view of the different species 

 of coals. It is the business of the artist or the manufac- 

 turer, to inform himself of their qualities, before he can 

 adapt them to their different uses. For all general 

 useful purposes, it will appear, that coals which contain 

 the most carbon, and the least sulphur or bitumen, 

 which burn slowly, and produce an intense heat, leav- 

 ing but a small residuum, are the most valuable and 

 economical. From the above description and analysis 

 of Rhode- Island coal, it will be seen, that it comes 

 nearer to the properties of pure carbon or charcoal, than 

 most others, and of course that, for most purposes in 

 which charcoal is used, it is equally applicable, and, for 



