122 FUELS 



out more quickly than hard coal, and the supply in the stove 

 has to be renewed frequently. 



Coke is a fuel which is growing in use. It is obtained by 

 the destructive distillation of soft coal. It is superior to soft 

 coal because it gives a hotter fire ; but it is inferior to hard coal 

 because it burns more quickly and requires more attention. 



In choosing coal we must consider the stove, because coal that 

 will burn well in one stove will be a failure in another. Hard 

 coal requires a strong draft underneath it and should not be 

 used in a stove which has a poor draft. Soft coal burns with 

 little draft under it, but requires a good draft over it to burn 

 the released gases. The stove or range must be studied and 

 tested, and coal which will suit it must be chosen. Then, too, 

 the householder is limited in his choice of fuel by the cost and 

 by the varieties which are available in his town. In some 

 countries briquettes are manufactured and used for fuel. They 

 are made in the shape of bricks and are composed of waste coal 

 dust and other substances. They are cheap and thoroughly 

 satisfactory. 



Coal gas, ashes, clinkers. Fires are usually banked at night 

 in order to keep the fire low until morning. But unless the 

 banking is carefully done a disagreeable odor of gas spreads 

 through the house. In banking a fire a blanket of coal sufficient to 

 last until morning is thrown on the glowing coals and the damper 

 that admits air and the exit damper in the chimney are closed. 

 If the fire is very hot, the burning coals are smothered from 

 above by fresh coal and are smothered from below by the closed 

 draft. The smothered coals undergo partial destructive dis- 

 tillation, and give off poisonous gases. Since the chimney exit 

 is closed, these dangerous gases accumulate in the furnace and 

 from there make their way through loose doors and joints into 

 the house. When this happens, the fire should have immediate 

 attention. Generally it is sufficient to open the chimney 



