ATMOSPHERIC ELECTRICITY. 347 



§ IV. Of the distribution of electricity in the clouds. 



Experiment shows that electricity is conveyed to the surface of con- 

 ducting bodies, and that it exhibits no trace of itself in their interior. 

 We may ask if it is the same with respect to clouds. Ought we to 

 regard the mass of vesicles which form a cloud as a single body, on 

 the surface of which all the electricity is distributed, or rather ought 

 we to admit that during the formation of a cloud each vesicle preserves, 

 in whole or in part, its atmosphere of electricity ? We are already ac- 

 quainted with the opinion advanced by M. Gay Lussac on this sub- 

 ject ; he supposed that the clouds which exhibit certain density are 

 similar to ordinary conductors and that the electricity is simply con- 

 veyed to their surface. M. Kaemtz* does not concur in this opinion. 

 In fact, if it were so, it would be difficult to explain how the clouds can 

 contain so great a quantity of electricity, as that which is observed in 

 storms ; how in this case the electricity does not neutralize itself by 

 a single explosion, or at least by a small number of explosions ; and 

 finally, how the charges of electricity ane reproduce so numerously 

 and so close to each other. Besides, the explosions ought to cease 

 with the first rain, since the communication which this establishes 

 between the cloud and the earth ought to allow the electricity to 

 escape freely. It appears more probable to M. Kaemtz that every 

 vesicle, whether it enters into the composition of a thunder-cloud or not, 

 preserves a portion of its electricity, and that this portion is greater 

 the nearer the vesicle is situated to the surface of the cloud. As to 

 the cause which might thus retain the electricity around each vesicle, 

 M. Kaemtz found it in the resistance which the electricity must experi- 

 ence in passing from one vesicle to another, a resistance which is 

 due to the imperfect conductibility of the air interposed. This 

 mode of considering the distribution of the electricity in the clouds 

 does not explain how the vesicles of vapor, electrified in the same 

 manner, form masses as limited as the clouds are, instead of diffusing 

 themselves uniformly by their mutual repulsion. 



M. Peltier t also regards the vesicles of vapor of which clouds are 

 composed as surrounded by an electric stratum. " A cloud," says he, 

 '■'■ is properly not a body such as is usually understood by this word ; 

 it is not a whole of which the particles are compacted as those of solid 

 bodies, nor even those of liquids by their adherence or proximity. 

 Held together with little force the particles of clouds do not readily 

 permit the propagation of electricity ; the s{)aces which separate 

 them maintain their isolation and their independence, and it is 

 only in their condensation, from whatever cause, that their masses 

 resemble in some slight degree ordinary bodies, and readily transmit 

 electrical changes. If these particles are widely separated, and 

 have consequently ]ireserved a great independence, they each re- 

 tain all their electric energy, the whole tension which they have 

 acquired, and the mass of vapor will act with a power propor- 



■-' Lebrlnich der Meteorologie, torn. II, page 414. 

 fComptes Eeudus, torn. X., pages 202 et 841. 1840. 



