M. Pouillet on the Electricity of Elastic Fluids. 47 



of valetudinarians, for writing dhout what he may chance not to 

 understand so well as his neighbours. 



FuNCHAL, Madeira, \Oth February 1829- 



Art. VII. — On the Electricity of Elastic Flmds, and on one 

 of the causes of the Electricity of the Atmosphere. By M. 

 Pouillet*. 



Since the discovery of Franklin respecting the electricity o^ 

 the atmosphere, there have been made in all civilized countries 

 numerous observations upon the phenomena which are depen- 

 dent upon this natural electricity. Thesebbservations have prov- 

 ed that stormy clouds are strongly electrified, the one positively, 

 and the other negatively ; that ordinary clouds have almost 

 always one of the two electricities, but too weak a charge to 

 produce the explosion of thunder ; — in short, they have found 

 that in a sky pure and cloudless, the air itself has a certain 

 electric intensity, and that this intensity seems to increase in 

 proportion as we rise in the higher regions. 



During the storms of our climates, and particularly during 

 the most violent storms of the tropics, the electricities of the 

 atmosphere recompose themselves in great quantities, and 

 destroy one another ; for lightning, it is well known, is a re- 

 composition of contrary electricities. It must, therefore, during 

 the course of a year, reproduce as much electricity in the at- 

 mosphere as was destroyed by the storms and by the other 

 electrical phenomena. Hypotheses without number have 

 been made upon the origin and upon the formation of this 

 prodigious quantity of electricity ; but the hypothesis of Volta 

 seems to be the only one which has any foundation. He sup- 

 poses that bodies become electric in changing their condition, 

 and that in consequence, the vapours of water which rise in- 

 cessantly upon the continents and upon the seas, ought to be 

 electrified by the single fact of its passage into the state of an 

 elastic fluid. This opinion has been but seldom contradicted, 



• Translated from the Ann. de Chim. torn, xxxv.p. 401. 



