Heat 99 



The kindling temperature is the temperature at which a sub- 

 stance will take fire. 



Temperature is measured by means of an instrument called 

 the thermometer. 



The most important kinds of fuel are wood, coal, charcoal, 

 peat, alcohol, oils and certain gases. 



Wood, coal, charcoal, peat, and coke are composed largely of 

 carbon. 



Liquid fuels, such as kerosene, gasoline, naphtha, fuel oil, and 

 alcohol are combustible materials called hydrocarbons. 



The principal gaseous fuels are coal gas and water gas. 



The unit of heat measure is the calorie. It represents the 

 quantity of heat required to raise one gram of water one degree 

 centigrade. The large Calorie, used in measuring the heat values 

 of foods, represents the amount of heat required to raise 1,000 

 grams of water one degree centigrade or one pound of water 

 four degrees Fahrenheit. 



The dangers of uncontrolled fire are great. Fire exits, fire 

 drills, and other means of fire protection should be provided in 

 schools and in all buildings where large numbers assemble. 



Fire extinguishers are of two types, those which act as cool- 

 ing agents and those which form a blanket shutting out the air. 



FACT AND THOUGHT QUESTIONS 



1. Mention effects of heat you have noticed in your own home. 



2. How may heat be liberated without fire? 



3. What is meant by the kindling temperature? 



4. Describe several ways in which fire is produced. 



5. Explain the origin of coal. Of peat. 



6. How is coke produced? Charcoal? Coal gas? 



7. Complete, orally, the following statements: 



(a) A thermometer is . 



(b) A degree Fahrenheit equals of a centigrade degree. 



(c) The original source of heat is . 



8. Why are smoke and fire sometimes produced when we drive an auto- 

 mobile with brakes on? 



9. Why does the smoke of a fire decrease as the flame increases? 



10. Why does a smouldering fire blaze up when stirred? 



11. Give reasons for conserving fuel resources. 



12. Name avoidable causes of fire in buildings. 



