Coal. 23 



is a tradition that a blacksmith first used it in 

 Liege as fuel. It was first used for manu- 

 facturing purposes about 1713. 



Coal is found laid down in great veins, 

 varying in thickness, in various parts of the 

 world in the upper strata of the Paleozoic 

 period. The age in which it was formed is 

 called by geologists the Carboniferous (coal- 

 bearing) age. 



Before going on to account for the deposits 

 of coal, let us stop a moment and consider 

 what it is. Chemists tell us that coal is 

 chiefly constructed of carbon, compounded 

 with oxygen, hydrogen, and nitrogen. There 

 are many varieties, but all may be classified 

 under two general headings bituminous and 

 anthracite. Bituminous coal contains a large 

 amount of a tarry substance, a kind of mineral 

 pitch or bitumen, which burns with a brilliant 

 flame and a black sooty smoke, exceedingly 

 rich in carbon. Anthracite coal is hard and 

 stone-like in its texture, burning with scarcely 

 any flame and no smoke. It produces a fire of 

 intense heat when it is once ignited. There 

 is another form of coal called cannel coal, 

 which is a corruption of "candle coal," so 

 called because a piece of this kind of coal 

 when ignited will burn like a match or pine 

 knot and give light like a candle. This is the 

 richest of all the coal deposits in gases that are 

 set free by heat, and for this reason is exten- 



