264 ELECTRICITY OF THE AIR ; LIGHTNING. 



such as water, metals, moist earth, fee, which 

 readily carry it, and are therefore called conductors. 

 Through these latter it passes easily, and always 

 gathers itself upon their surfaces, if, by being sur- 

 rounded by non-conducting matters, it is hindered 

 from going farther. You must remember, too, 

 that, according to the views of many naturalists, 

 there are supposed to be two electric fluids, the 

 positive and the negative, each of which, indeed, 

 taken by itself, seems to have exactly the same 

 properties as the other; but that there is this 

 great difference between them, that, while bodies 

 charged with the same sort of electricity — for in- 

 stance, with the positive — drive each other away, 

 two that are charged with the different electricities, 

 that is, the one with the positive, the other with 

 the negative, are always drawn together. 



A body is said to be electrised when it is 

 charged with one or the other of the electricities. 

 All bodies commonly, that is, when not in the 

 electric state, contain the two electricities equally, 

 each of which therefore exerts, on things around, 

 its own peculiar action, which, being neutralised 

 by the other, is not to be perceived. If, however, 

 an electrised body is placed near one that is 

 excited, that electricity in the latter, which is 

 the same as that of the former, is driven away 

 from the neighbouring electrised body, and the 



