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Why do Electrised Bodies Recede from each other ?*
By CHARLES Griffin, Esq., M.L.E.S. Read, in three parts, at the Electrical Society, Oct. 15th, Nov.5th and 19th, 1839.
I shall in this, my third paper, (being the second on the above question,) attempt a somewhat more particular and definite explanation of the singular phenomenon of recession, according to the propositions at the end of my last paper.
I shall not pretend to go so far as to assert that this phenomenon must be explained entirely after my own manner, but endeavour to point out a mode that may perchance enable some electrician, versed in mathematics, to reconcile the doctrine of one electric fluid with the fact of the recession, not only of negatively, but also of positively electrified bodies, from each other, on principles long well known and established, without resorting to the mere assumption of a power of repulsion.
I have thought it best, considering my own ignorance of mathematics and the abstruseness of my subject, to err on the side of prolixity rather than on that of brevity ; to risk saying something unnecessary, rather than leave anything necessary to my being understood, unsaid.
The greater portion of my second paper, read to the London Electrical Society, (published in the "Annals of Electricity," vol. 3, p. 126,) was contained in papers transmitted to the Royal Society, on the 7th of June, 1833. In the same papers was stated generally my opinion that the electric fluid possessed the power of homogeneous attraction, as also in a letter in the " Mechanics' Magazine of 3rd November, 1836, under the signature of “Corpusculum.” The inverted commas in my said second paper in the Annals were intended to indicate the parts comprised in the papers transmitted to the Royal Society, but those commas are unfortunately misplaced. They comprised the greater part of such second paper, particularly the 1st, 4th, 5th, 8th, 9th, 11th, 13th, 15th, 16th, and first seven words of the 14th propositions. I may be excused this note, in order to anticipate charges of plagiarism.-C. G.
Ann. of Elec.--Vol. VIII.--No. 1.--Jan., 1842.
(1.) Proposition 1.— I rest principally on the usual simplicity of natural operations, or paucity of causes employed in nature, to produce a multiplicity of effects.*
Prop. 2 and 3, I have before considered.
Prop. 7 is not essential to the principal question discussed in this paper.
(2.) To illustrate prop. 8, let the inner circles, abcd, plate 1, fig. 1, represent a portion of an indefinite line of metallic balls, equidistant, extending in each direction from the ball b, and supposed insulated, and the dotted circles their natural films or coatings of free electric fluid or liquid. The electricity of b is here attracted by the solid matter of its own ball, and also by the solid matter of a and c, and their solid matter is likewise attracted by the electricity of b and their other next adjacent balls, and the like of each ball throughout the series. Now, a b c d and the other balls being equidistant, and possessed of equal portions of free electricity, the electricity of either, as b for instance, cannot be attracted by the solid matter of its next adjacent balls, as a and c, in one direction more than another, the quantities of solid attracting matter in each direction being equal. Likewise, the solid matter of b, or any other ball, cannot be attracted in one direction more than another, the quantities of electricity attracting it in each direction being equal. Under these circumstances, the electricity of each ball may be termed free electricity quiescent.
(3). Prop. 9.-To illustrate this proposition, let b, fig. 2, be one of the line of metallic balls before mentioned, having more than its natural share of free electricity, and a c d other such balls, having each its natural share only. Here, the free electricity of b, having been increased, must become active, and exert increased attractive influence on the solid matter of the adjacent balls, as a and c, whose free electricity has not been increased, and give those bodies an increased tendency to approach b. The free electricity of b may then be called free electricity active.
(4.) Prop. 1o, fig. 2.—When the solid matter of b, which, in its
* When I say one fluid, I rather mean to deny that the positive and negative states are the separation of a vitreous from a resinous fluid, and not to assert that the common electric stream is composed but of one fluid. I think that that stream may be one principal fluid, (which I call electricity,) accompanied by or combined with caloric in a liquid state, or holding it, and perhaps very minute portions of metallic and other substances, in solution. It appears to me not improbable that the atmospheric atoms, as well as the surfaces of other bodies, are surrounded by films of liquid electricity and caloric, and perchance different strata of the two united in different definite atomic proportions; thereby giving rise to the varieties of colour, (as I endeavoured to shew some reasons for in the “Mechanics' Magazine” of 13th Ma 1837,) and also causing that elasticity, or expansion and recession from each other, of the atmospheric atoms, which is so confidently attributed to a power of homogeneous repulsion, a power assumed (most paradoxically) to belong to the same two particles of matter, when near together, which are known and admitted to possess that of homogeneous attraction when at a greater distance from each other.
natural or unelectrified state, exerts a certain force of attraction on the free electricity of c, is required to exert an attractive influence on an additional quantity of free electricity communicated to itself, it must lose some portion of its attraction for the free electricity
(5.) We might infer this by analogy, from the instance of a magnet; one, for instance, supporting a pound weight of iron, and capable of supporting that weight only. On the approach of another piece of iron, the magnet transfers a portion of its attractive influence to that approaching piece, and therefore drops the pound weight, and this although the aggregate forces exerted by the magnet on both pieces together, would be increased so as to equal more than a pound.
(6.) Were this otherwise, the attraction of two masses of matter (a piece of iron and a magnet, for instance,) would, to a considerable extent, increase in arithmetical proportion to the increase of one of them, and either of them support an enormous mass of the other.
(7.) Prop. 13, fig. 2.-[Referring to the words vice versa.] The natural quantity of free electricity of the ball c (adjacent to b), being required to exert a lessened amount of attraction in the direction b, is left at liberty to, and must, exert an increased attraction for the solid matter of the ball d. It will then have become free electricity active, as well as that of the ball b.
(8.) Prop. 14, fig. 2.—The solid matter of c, being called upon to exert an increased attraction by the added electricity of b, and thereby become active on that side of it, must lose some portion of its attraction for electricity in the opposite direction, (that of d, for instance,) and must have an increased tendency to approach the electricity of b, by the preponderance of the attraction in that direction.
(9.) As to the changes of attraction mentioned in the propositions 13 and 14, between a body (adjacent to an electrified body) and its own electricity, those propositions go too far ; they certainly contradict each other on that point. However, as I do not see my way clearly, and as the settlement of the point does not seem essential to the main question of recession, I pass it by for the present.
(10.) Prop. 15.—This appears by proposition 14 and fig. 2. The tendency of c to part with electricity to d, and to abstract it from b, and of d to part with electricity to e, and abstract it from c, and the like of every more remote ball, is evident.
(11.) A portion of electricity will have been removed further from its own ball, and consequently have diminished its attraction for that ball, while it will have approached nearer to the next more remote ball, and thereby have increased its attraction for that ball.
(12.) When this attraction for c, or any more remote ball, shall have been so far increased as to exceed the force of attraction of b, or the next ball towards b, and the homogeneous attraction of the