.VOL^ XLV.] PHILOSOPHICAL TRANSACTIONS. 479 



Exper. 4. As the tube, when strongly excited, will not only attract, but 

 afterwards repel any light bodies brought near it; in like manner the cork-ball 

 will be endued with the same property ; so that a smaller ball will first be attracted 

 towards it, and then repelled from it, the same as the leaf-gold in exp. 1, and on 

 touching any other body it will be again attracted; and this may be repeated se- 

 veral times, when the smaller ball is much less than the larger one, though the 

 effect will constantly be weaker and weaker, as every time the less ball is attract- 

 ed, it carries off with it some of the electric virtue, and is also endued with the 

 same properties as the larger ball. 



Mr. Gray, Mr. Dufay, and others have observed, that this electrical quality is 

 not only to be excited in glass, but in most solid bodies capable of friction (metals 

 excepted) ; though in some it will be scarcely sensible, and that it is found to be 

 strongest in wax, resins, gums, and glass: and as glass is the easiest procured of 

 a proper form, it has generally been used in majcing these experiments. It has 

 been further observed, that those bodies in which the electrical quality is capable 

 of being excited the strongest by friction, will receive the least quantity of it from 

 any other excited body, and therefore are properly made use of to support any 

 body designed to receive the electrical virtue. The truth of this will sufficiently 

 appear from the following experiment. '■> iJuniid) 



Exper. 5. Hang up two lines, one of silk, and the other of thread; that of 

 thread will be attracted by the tube at a much greater distance than the silk. 

 Again; fasten to each string a feather, or other light body; if the tube be brought 

 to the feather fastened to the silk, it will be first attracted, and afterwards re- 

 pelled: and from the virtue communicated to it from the tube, the several fibres 

 of the feather will strongly repel each other. But when the tube is brought to 

 the feather fastened to the thread, the feather will be strongly attracted, and con- 

 tinue to be so without ever being repelled, the virtue passing off by the thread it 

 is hung to. If a glass ball be hung to the silk line, it will be weakly attracted by 

 the tube ; but one of cork or metal much stronger. 



Exper. 6. Let a rod of iron be sustained by silk lines, and by means of a glass 

 sphere (which can be more regularly and constantly excited than a tube) be made 

 electrical, it will be found to have all the properties of the excited tube mentioned 

 in exp. 1. A stream of light will come from the end of it, if it be pointed; it will 

 attract, repel, and communicate this virtue to any other non-electric body; on 

 the approach of a non-electric, a spark of fire, with a snap attending it, will 

 come from it; which spark will be greater or less, as the bodies approaching it 

 have more or less of the electrical quality residing in them ; and there will like- 

 wise be the same offensive smell as was observed of the tube. 

 ; From these experiments, containing the principal phenomena of electricity, 

 may justly be drawn the following conclusions: 1st. That these remarkable phe- 

 nomena are produced by means of effluvia; which, in exciting the electrical body. 



