the different kinds of Coal. 65 



this purpose^ from the weight of 0.1 gramme employed, there is 

 subtracted the sum of the three quantities found for the carbon, 

 the hydrogen and the ashes. The remainder indicates the quan- 

 tity of oxygen. 



It is in this manner that M. Karsten has conducted the eleven 

 essays mentioned above. For example, he found that coal of 

 the first quality from the celebrated mines of Newcastle in Eng- 

 land, coal with intumesced coke, is composed for 100 parts in 

 weight as follows. 



Carbon, - * 84,263 



Hydrogen, - - 3,207 



Oxygen, - - 11,667 



Earthy parts or ashes, - 0,863 



Total, - 100. 



Whence there follows, that proportionally, and abstraction 

 made of the contents in earths, this same coal, considered then 

 as a pure combustible, would )be composed of 



Carbon, - - 84.99 



Hydrogen, - . 3.23 



Oxygen, - - 11,78 



/ Total, 100. 



If the results of all these analyses be glanced over, it is imme- 

 diately remarked, that the relation of the quantity of carbon to 

 the quantity of oxygen and hydrogen, which occurs in the dif- 

 ferent species of mineral combustibles, decides nothing with re- 

 spect to the nature of the charcoal that is obtained as a residuum 

 of their distillation. The contents in carbon are seen rising from 

 76 to upwards of 96 per cent. 



Thus in the varieties of coal, such of their constituent parts as 

 are not carbon may remain under four per cent., and that with- 

 out the combustible ceasing to present the regular characters of 

 coal. It might even be said, that the combustible, in its ex- 

 ternal appearance, approaches so much the more to brown coal, 

 or lignite, that its contents in carbon diminish. 



In order to present a more distinct view of the relations in 

 which the oxygen and hydrogen stand to the carbon, in the dif- 

 ferent species of coal, the author has put together the substances 

 analyzed in a table, indicating, with rpgard to each of them, how 



APRIL— JUNE 1827. E 



