COAL 219 



best conveyed by the statement that it is very ancient 

 "peat," compressed and naturally changed by chemical 

 action and retaining little or no trace of its original 

 structure. Peat, as we know it from the low land of 

 English and French river valleys and the bogs of Scotland 

 and Ireland, is formed by the annual growth and death 

 of " mosses " of several kinds and of other accompanying 

 vegetation. It retains the woody forms of the vegetable 

 growths which constitute it, and they are often but loosely 

 adherent to one another. Peat may be merely a growth 

 of the past five years, but is sometimes many thousand 

 years old. Older than peat, and more caked and com- 

 pressed, is lignite, or brown coal, which occurs on the 

 Continent of Europe, also in South Devon and elsewhere, 

 in geological strata newer than those which yield our black 

 coal. Then we have the most important class of black 

 coals which are known as " bituminous coals," because they 

 soften when heated and form hydrocarbons of both viscid 

 and gaseous nature. They are used for domestic pur- 

 poses, and wherever flame is desired. They are, in fact, 

 the " lumps of coal " familiar in our scuttles. The 

 " bituminous coal " with the greatest amount of hydrogen 

 in it is the cannel or candle coal, so called from its bright 

 flame when burning. This kind is especially valuable for 

 gas-making, and of smaller value as fuel. The term 

 " anthracite " is reserved for a hard, stone-like coal which 

 is very nearly pure carbon (ninety per cent). This class 

 of coal burns with a very small amount of flame, gives 

 intense heat, and no smoke. It is used in drying malt 

 and hops. 



Like all woody matter, that from which peat is formed 

 consists of a combination of the elements carbon, hydrogen 

 and oxygen ; and these remain in somewhat changed 

 chemical union in the brown coal, bituminous coal, and 

 anthracite. The carbon and a varying and small propor- 



