ELECTRICITY IN THUNDER-STORMS. 689 



is actually accomplished by the operations which I have here dis- 

 closed. 



A certain organic substance expands under chemical composition, 

 and afterward contracts under chemical decomposition. Its disintegra- 

 tion is incited by the dynamical influences of the medium ; its reinte- 

 gration is brought about by its own inherent chemical affinity, which 

 affinitive power effects its combination with complemental material 

 furnished by the medium. 



In pursuing the inquiry here begun, the next step would be to show 

 how complications of these sundry phases of the one central fact of 

 motility lead to definite organization in various directions, and to the 

 rise of sensation. 



** 



ELECTEICITY IN THUNDEB-STOEMS. 1 



Br ELISHA FOOTE. 



THE great development of electricity in thunder-storms has been a 

 subject of much speculation. Its explanation, however, is still an 

 unsettled question. Some views on this subject are presented in this 

 paper. 



We have no evidence that the production of fogs or clouds the 

 change from invisible to visible vapor, or from combined to uncombined 

 moisture produces any electricity. All experiments to establish such 

 a supposition have had a negative result. 



These particles of vapor we may suppose to be small spherules, each 

 with its normal portion of electricity that surrounds or occupies the sur- 

 face of the sphere. "When two of these particles unite and form one, 

 the combined particle will have twice the electricity of either of the sepa- 

 rate parts, but not twice the surface. There will then be an accumulation 

 of electricity upon the surface of the combined particle; and still more 

 will this be so when thousands of these spherules unite to form a drop of 

 water. 



We may well conceive, therefore, that a cloud forming water should 

 become surcharged with electricity, that will escape in violent explosions 

 when the accumulation is too rapid or the circumstances are unfavor- 

 able to its being carried off by the surrounding moist air. 



It is not, then, the formation of vapor, but its condensation to rain, 

 that produces thunder and lightning. And this, it is believed, accords 

 with all our experience. Clouds are constantly forming and disap- 

 pearing; fogs and vapors are accumulated in some places in great abun- 

 dance, but no electrical excitement has ever been observed. But, on 

 the other hand, there is never a flash of lightning without a manifest 



1 Paper read before the Philosophical Society of Washington. 

 roL. xiii, 44 



