126 



INTRODUCTION TO GENERAL SCIENCE 



References : 



1. 1103:9. 



2. 1304:230. 



3. 1503:94-95. 



4. 1601:11. 



5. 1702:68-71. 



6. 1703:110-113. 



7. 1710:4. 



8. 1710:16-19. 



9. 1710:40-44. 



a. 1102:47-48. 

 6. 1102:159. 



c. 1312:349-351. 



d. 1709:177. 



e. 1903:49-51. 



Microscopical Impurities in the Air. 

 'Other Constituents of the Atmosphere. 



Relation of Bacteria to Nitrogen and to 

 Plants. 



Composition of the Atmosphere. 



Other Constituents of the Atmosphere. 



Other Constituents of the Atmosphere. 



Constituents of the Air. 



Substances in Suspension in the Air. 



Sources of Contamination of the Atmos- 

 phere. 



The Dust of the Atmosphere Colors of 

 the Sky. 



Dependence of Cloud Condensation on 

 Dust. 



Composition of the Atmosphere. 



The Carbon-Oxygen and the Nitrogen 

 Cycle. 



Bacteria in the Air. 



92. ATMOSPHERIC ELECTRICITY 



Lightning is the greatest manifestation we have of atmos- 

 pheric electricity, and the aurora is a close second in grandeur, 

 if not in energy. The aurora may owe its origin to the elec- 

 trical energy which the earth receives from the sun, but the 

 source of atmospheric electricity is not known, unless friction 

 causes it. 



Electrification is produced by two different layers of air 

 rubbing upon each other; by drops of water falling on water, 

 or on a solid; and by snowflakes slipping by one another. 

 All these conditions increase their effect with increasing wind 

 velocity. Nevertheless, these effects all combined do not 

 account for the enormous charges which accumulate in the 

 clouds, and which are induced in the earth. 



