OIL AND GAS AS FUEL 123 



damper for a few minutes ; this secures the immediate escape 

 of the harmful gases. Meanwhile the smothered fire has 

 burned so low that it does not produce more coal gas than 

 can escape through loose outlets in the chimney flue. If the 

 fire is hot, the chimney damper must be left wide open for a 

 short time after shutting off the air inlet and smothering the 

 fire with dead coals. If the fire is low, coal gas does not 

 form after " banking," because the temperature is too low to 

 produce the dangerous gas even though the air is shut off. 



The bugbear of every wood and coal fire is ashes. They must 

 be removed and the stove must be cleaned if the fire is to burn 

 satisfactorily. Why do we have ashes ? Because the vegeta- 

 tion from which coal comes does not consist solely of oxygen, 

 hydrogen, and carbon, but of these substances along with 

 small quantities of other substances which will not burn. 

 These foreign substances are largely minerals, and they are not 

 driven off in the decomposition, neither are they burned up in 

 the fire, but they remain to plague the fire tender. Occa- 

 sionally some of these foreign substances fuse together and 

 form clinkers, another abomination of the housekeeper. 



It is a well-known fact that silver tarnishes more readily in 

 winter than in summer, but few housewives understand why 

 this is true. Coal almost always contains a small amount of 

 sulphur. Some of this sulphur escapes from the heated coal 

 along with the other gases and sulphur unites with silver, form- 

 ing a black film. In steam and hot-water heating, less sulphur 

 compounds reach the rooms than in hot-air heating, and there 

 is less tarnishing of the household silver. 



Oil and gas as fuel. In summer homes in the country, in 

 vacation camps, and in small towns and villages, oil is largely 

 used for fuel. Those of us who live in cities where coal can al- 

 ways be purchased or where gas is available for stoves in every 

 house, large or small, expensive or cheap, have no idea how 



