SMOKE; ITS CAUSE AND PREVENTION 95 



TABLE III. COMPOSITION OF SOLID FUELS 



IV. SMOKE; ITS CAUSE AND PREVENTION 



109. The Cause of Smoke. Because of the high percent- 

 age of volatile matter in soft coal, it is likely to produce much 

 black smoke unless precautions are used to prevent it. The 

 principles concerned in smoke production are identical with 

 those explained in connection with the smoking candle and 

 the oil lamp. Hydrocarbons produced by the heated coal are 

 decomposed more or less completely into hydrogen and 

 carbon. Failure of the carbon to meet a sufficient supply of 

 oxygen at or above the kindling temperature of the carbon, 

 causes more or less of the carbon to be carried up the chimney 

 unburned, making its appearance as black smoke. Even 

 though the temperature of volatile matter is kept sufficiently 

 high until it meets oxygen, if the supply of the latter is in- 

 sufficient, the carbon will be incompletely burned at .best. 

 It may be burned to CARBON MONOXIDE instead of CARBON 

 DIOXIDE. This means a loss of heat, since less than one-third of 

 the energy of the carbon is liberated as heat if it is burned to 

 carbon monoxide instead of carbon dioxide. 



110. Some of the Evils of Smoke. The Smoke Nuisance. 

 The production of black smoke means, not only poor combustion 

 of the coal and hence a loss of heat, but also injury to health 

 and property. People who are compelled to live and work 



