OTHER FUELS 161 



8. How may you test the amount of gas consumed per hour by 

 the different gas-consuming appliances? 



9. Test some appliance at home. 



10. Report on the condition of your gas meter as to a leak. How 

 may you determine such a condition? 



11. Why should gas burners be well adjusted? 



12. Why do gas burners sometimes " burn back"? How may 

 this be prevented? Why should one never allow a burner to 

 " burn back "? 



13. Find the gas pressure of your city in inches of water by 

 attaching a U-shape tube half full of water to a gas fixture. The 

 difference in the water level represents the gas pressure in inches. 

 A column of water 1 foot high weighs 0.434 of a pound per square 

 inch. Find the gas pressure in pounds in excess of the atmospheric 

 pressure. 



14. Why will a matoh go out if the match is held in such a posi- 

 tion that the burning head will be above the wood? 



15. Why must a fire be lighted at the bottom of the pile of wood? 



16. Why does a flame burn just above a log in a fireplace? 



17. Why may a candle be considered a gas generator? 



18. Why does a candle or lamp smoke for a moment after being 

 blown out? 



OTHER FUELS 



Water Gas. Water gas is used in some cities as an illuminant. 

 This gas is made by passing very hot steam over red-hot anthracite 

 coal or coke. This gas burns with a colorless flame; therefore, it 

 is necessary to mix some gas containing carbon with it in order to 

 produce an illuminant. Oil is used for this purpose. As water gas 

 is very poisonous, great care must be taken to prevent its escape 

 into the room. 



Natural Gas. A cheap and convenient gas has been obtained 

 from the earth. Natural gas is produced by the great heat within 

 the earth acting upon the vegetable and animal matter at great 

 depths. It is found in a highly compressed state in the pores of 

 rocks. Wells are drilled into the earth, and the gas piped to the con- 

 sumer. 



