WHAT COAL SHALL WE USE IN THE HOME? 121 



But some manufacturers know that the unburned carbon 

 particles have a high fuel value. These manufacturers use 

 stokers, automatic devices which prevent the escape of unburned 

 carbon particles. The heat from these more than pay for the 

 stokers and the community is spared the smoke (Fig. 49). 



*4 



FIG. 49. The three chimneys which show no smoke are from furnaces equipped 

 with automatic stokers and large combustion chambers. By these devices it is 

 possible to consume the carbon of the fuel completely, thus preventing the es- 

 cape of black smoke. 



What coal shall we use in the home ? Generally speaking, 

 hard or anthracite coal is the most desirable for household use. 

 It burns with a pale blue flame, without smoke or disagree- 

 able gases. An inexperienced person has greater difficulty in 

 starting a fire from hard coal than from soft cpal, because hard 

 coal is more difficult to ignite ; but when hard coal is once 

 ignited and the fire is successfully made, less care is necessary 

 than with any other solid fuel. Soft or bituminous coal burns 



