224 On the Rhode- Island Coal. 



cross fracture is conchoidal, and the sides of its natural 

 divisions are sometimes covered with a ferruginous 

 earth. It burns slowly, producing an intense heat, 

 without smoke, and with a very light lambent flame ; 

 but emits no sulphureous or bituminous vapour, and, 

 when perfectly burnt, leaves a very small quantity of 

 grey ashes. The unconsumed particles of it retain their 

 original colour and lustre. 



Specific gravity, from 1,450, to 1,750. 



From the above description, little doubt can remain 

 of the true character of this coal ; but, in order to ascer- 

 tain, with precision, the quantity of ingredients which 

 it contained, I examined it according to the rules so 

 ably laid dpwn by Kirwan, and, as my object was prin- 

 cipally to determine the proportion of carbon which it 

 contained, as the substance upon which all its good 

 qualities depend, I repeatedly deflagrated it with certain 

 proportions of nitre, and uniformly found, when the 

 experiment was made with proper attention, that 100 

 parts of coal contained from 90 to 94 of carbon ; and 

 in order to compare it, in this respect, with the charcoal 

 in common use here, I found that it required more 

 charcoal to saturate a given proportion of nitre, than it 

 did of Rhode- Island coal. These experiments were 

 also confirmed, by submitting 100 grains of the coal to 

 an intense heat in a crucible, which, after five hours, 

 were reduced to six grains of ashes; those ashes, which 

 consisted, perhaps, of an oxyd of iron and an earth, 1 

 had not leisure to examine ; nor was it of much conse- 

 quence in the main object which I had in view, which 



