ELECTRICITY. 



attending electrical attraction, we should 

 be provided with stands, from the ends 

 of which are suspended by their respec- 



Fig5. 



tive threads one or two pith balls, about 

 the size of a small pea, as shown in 



2. Distribution and Transference. 



(16.) If an excited electric be brought 

 near a pith ball suspended by silk, the 

 ball will, in the first place, approach the 

 electric (fig. 6.), indicating an attrac- 

 tion towards it, and if the position of 

 the electric will allow, the ball will come 

 into contact with it and adhere to it for 

 a short time ; but it will presently after- 

 wards recede from the electric, showing 

 that it is now repelled, (fig. 7.) If we 



Fig. 6. 



Fig. 7. 



now remove the electric, and present to 

 the ball which has thus touched it, a 

 second ball which has had no previous 

 communication with any electric, we 

 find that these two balls attract one 

 another, and come into contact. The 

 same actions are repeated between this 

 second ball and a third, which may be 

 presented to it ; and so on in succession, 

 but with a continued diminution of in- 

 tensity. This diminution plainly indi- 

 cates a diminished power, in conse- 

 quence, as it would seem, of its being 

 distributed among a number of bodies. 

 (17.) In the prosecution of these 

 experiments, therefore, the effects will 

 be more distinct, if, instead of small 

 pith balls, we employ a globe of metal 

 of larger size, which will allow of the 

 reception of a considerable quantity of 



this electric influence by contact with 

 the excited electric. A globe, suspended 

 by silk threads, as the pith balls are, 

 and which has extensively touched the 

 electric, will act upon these balls pre- 

 cisely in the same way as the original 

 electric would have acted upon them, 

 and may accordingly be substituted for 

 it in all these experiments. It is, indeed, 

 exactly in the same condition as the 

 globe rubbed by an electric, already 

 mentioned. ($ 11.) 



(18.) From the whole of these facts 

 we necessarily infer that the electric has 

 imparted to the ball or globe which 

 came in contact with it, properties ex- 

 actly similar to those which had been 

 excited in itself by friction. By repeated 

 contact with a number of bodies, an 

 excited electric is found to lose its elec- 

 trical powers in the same degree as 

 these powers have been acquired by the 

 bodies themselves ; and fresh excitation 

 alone can renew them. It is evident, 

 then, ,that the unknown agent, which 

 we have termed Electricity, is capable 

 of transference, in the same sense in 

 which we speak of heat being communi- 

 cated or transferred from one body to 

 another, and that, like heat, it is weak- 

 ened by diffusion among a number of 

 bodies. 



(19.) If the electrified ball be touched 

 with the finger, it will be deprived of 

 the whole of its electricity, which will 

 pass into the body of the person who 

 touches it. It is now reduced to its 

 original or natural state, and is again 

 susceptible of being attracted, either by 

 an excited electric, or by another body 

 to which electricity has previously been 

 communicated. 



If the electrified body, instead of 

 being touched with the finger, had been 

 touched by a rod of metal held in the 

 hand, the effect would have been the 

 same in both cases : hence we may 

 infer that the metallic rod is capable 

 of conveying away from the body the 

 whole of its electricity. But if a glass 

 rod be substituted, the result is very 

 different ; the body touched is found to 

 retain the whole of its electricity, not- 

 withstanding the contact of the glass 

 rod. We are thus led to the conclusion 

 that some substances, such as glass, 

 are incapable of conducting electricity ; 

 while others, such as the metals and 

 the human body, readily convey that 

 influence. 



(20.) It is invariably found that all 

 electrics are, at the same time, non-con- 



