282 COMMON ELECTEICITY. SECT. XXVIII. 



SECTIOX XXVIII. 



Common or Static Electricity, or Electricity of Tension A Dual Power 

 Methods of exciting it Attraction and Repulsion Conduction 

 Electrics and Non-electrics Induction Dielectrics Tension Law 

 of the Electric Force Distribution Laws of Distribution Heat of 

 Electricity Electrical Light and its Spectrum Velocity Atmos- 

 pheric Electricity Its cause Electric Clouds Violent effects of 

 Lightning Back Stroke Electric Glow Phosphorescence. 



ELECTRICITY is a dual power which gives no visible sign of its 

 existence when in equilibrio, but when elicited forces are de- 

 veloped capable of producing the most sudden, violent, and de- 

 structive effects in some cases, while in others their action, though 

 generally less energetic, is of indefinite and uninterrupted con- 

 tinuance. These modifications of the electric forces, incidentally 

 depending upon the manner in which they are excited, present 

 phenomena of great diversity, but yet so connected as to justify 

 the conclusion that they originate in a common principle. The 

 hypothesis of electricity being a fluid is untenable in the present 

 advanced state of the science ; we only know that it is a force 

 whose action is twofold ; that bodies in one electric state attract, 

 and in another repel each other ; in the former the electricity is 

 said to be positive, in the latter negative ; and thus regarding it 

 as a force, its modes of action come under the laws of mechanics 

 and mathematical analysis. 



Electricity may be called into activity by the friction of hete- 

 rogeneous substances, as in the common electrifying machine, by 

 mechanical power, heat, chemical action, and the influence of 

 magnetism. We are totally ignorant why it is roused from its 

 neutral state by these means, or of the manner of its existence 

 in bodies ; but when excited it seems to produce a molecular 

 polarity or chemical change in the ultimate particles of matter. . 



The science is divided into various branches, of which static 

 or common electricity comes first under consideration, including 

 that of the atmosphere. Substances in a neutral state neither 

 attract nor repel. There is a numerous class called electrics in 



