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XVII. On the Electrical Condition of the Atmosphere. 

 By Reuben Phillips, Esq.* 

 182. TTAVING in former papers proved that the friction of 

 J- A air against water produces electricity, and having 

 shown that the origin of atmospheric electricity can be found 

 in the friction of wind on drops of rain, I inferred that the upper 

 regions of the air were left by the descent of rain in a negative 

 condition. I look upon the following as a direct proof of the 

 existence of this negative state of the atmosphere, which leads 

 to some other conclusions. 



183. The positive electricity which the earth receives from 

 lightning and rain must rapidly find its way back to the atmo- 

 sphere, for the earth is electrically neutral under ordinary cir- 

 cumstances, as is known by comparing its state with the abso- 

 lute electric zerof- Again, the atmosphere when explored by 

 rods or kites gives a positive charge when the air is clear ; there- 

 fore the air itself, so far as the modes of exploration extend, is 

 positively electrified. But since the earth is neutral, the upper 

 regions must be negative ; or we have a quantity of positive 

 electricity existing in the atmosphere, and its equivalent of ne- 

 gative electricity nowhere — which latter supposition the whole 

 body of electrical science forbids. 



184. The atmosphere, then, may be regarded as consisting of 

 two spherical orbs, the lower one positively, and the upper one 

 negatively electrified ; and these two orbs induce towards each 

 other, leaving the earth neutral. Now the positive electricity 

 will, both from conduction and convection, continually travel 

 upwards. This seems to explain the fact, that the positive elec- 

 tricity is stronger at some distance than at I lie surface of the 

 earth. 



185. Since the positive and negative orbs of the atmosphere 

 induce towards each other, they must mutually attract. This 

 attraction is counterbalanced by the elasticity of the atmosphere ; 

 consequently it is difficult not to admit that the atmosphere is 

 condensed by the electric force between the mutually attractive 

 volumes. There are not, so far as I am aware, any data whereby 

 to determine what the absolute intensity of the electrical state 

 of the atmosphere is, and it is therefore impossible to assign any 

 value to the amount of condensation thus effected. Aurora may, 

 perhaps, sometimes be occasioned by electricity forcing its way 

 along and between these oppositely electrified orbs, as well as 

 by its coming to the earth. The general tendency of the air to 

 rise in the warmer, and, as a concomitant result, its downward 

 tendency in higher latitudes, is possibly not without its effect in 



* Communicated by the Author. 



t Faraday. Phil. Mag. vol. xxix. p. 257. 



