FRICTIONAL OR STATIC ELECTRICITY 189 



neys should have rods on them because soot is a good con- 

 ductor, as is also the vapor which arises when fires are 

 burning. 



Questions 



1. What is frictional electricity? 



2. Has frictional electricity industrial importance? 



3. What is a Leyden jar? 



4. Does frictional electricity cause any danger? Explain. 



5. How may this danger be removed? 



6. Describe an electric neutralizer. 



7. For what are humidifiers used in mills? 



8. Describe lightning. 



9. What dangers are attached to it? 



10. Name the different forms of lightning. 



11. Explain the relation of thunder to lightning. 



12. What is a lightning rod? 



