Heat 91 



bituminous coal. Anthracite coal is found in mountainous 

 regions. 



Hard coal is especially desirable for household purposes since 

 it burns with little or no flame and is nearly pure carbon. Soft 

 coal is used largely for industrial purposes. It contains many 

 carbon compounds and burns with a yellow flame. As it pro- 

 duces much soot and smoke, it is not desirable for household 

 purposes, though it may be so used. 



Peat. -Peat is a substance of vegetable origin composed of 

 moss, twigs and roots of trees in various stages of decay. It is 

 found as a kind of turf in places that were once swamps or 

 the borders of lakes. Peat bogs are found in many parts of the 

 earth. Some of them in Ireland are said to be over forty feet 

 deep. The turf-like substance is dug out of the bog, dried, 

 pressed into blocks and used as fuel. Most of the carbon of 

 this former vegetation, which in the air would have been oxi- 

 dized into carbon dioxide, has been preserved under water in 

 the swamps and therefore makes good fuel. 



Charcoal. Charcoal is nearly pure carbon. It is made by 

 putting wood into closed, air-tight chambers, called retorts, and 

 subjecting it to heat. By this process the wood is changed into 

 a porous black solid, which burns very easily. When burned, 

 it produces intense heat. In making it, certain valuable by-prod- 

 ucts are yielded, among which is wood alcohol. 



Coke. Coke is manufactured from soft coal in much the 

 :same way that charcoal is made from wood. In producing it, 

 by-products are yielded, among which are illuminating gas, creo- 

 sote, benzene, carbolic acid and ammonia. Coke is largely used as 

 a fuel and in separating metals from the ore in which they are 

 ;found. 



Liquid Fuels. The liquid fuels, kerosene, gasoline, naph- 

 tha, fuel oil, and alcohol, are combustible materials called 

 hydrocarbons. They are compounds of carbon and are made from 

 petroleum, a crude, dark, bluish-brown, oily substance, obtained 

 from the depths of the earth. The petroleum is boiled and its 

 vapor collected and then condensed to liquid by cooling. You 

 can easily understand this by recalling how the steam of boiling 



