244 MR. HARRIS ON SOME ELEMENTARY LAWS OF ELECTRICITY. 



hypothesis of Franklin and ^pinus, many acute inquirers have contended, on the 

 authority of the Earl of Stanhope *, that the recession of electrified bodies is depen- 

 dent on atmospheric attraction, and that such recession would not occur in a void ; 

 whilst others, in accommodating electrical divergence to the hypothesis of the French 

 philosophers, endeavour to show, that although greatly dependent on the presence of 

 an atmospheric medium, it still arises out of a repulsive force existing in the elements 

 of the electrical principle itself-f-. It was upon the above statements that I adopted, by 

 way of precaution, the method of using the gold-leaf electrometer in experiment (f.), 

 fig. 12. My subsequent researches, however, with electrified bodies in receivers, more 

 or less exhausted of the contained air, led me to investigate this point very rigorously ; 

 and I am inclined to think that the following fact, taken in connexion with the pre- 

 ceding (44. 74. 75.), will go far to show, that any explanation of the phenomenon 

 of electrical divergence involving the necessity of an atmospheric action, upon any 

 principle of mechanism whatever, is likely to be quite fallacious. 



(x.) Two gold-leaves were suspended in free space from a stout brass wire supported 

 horizontally on a long insulating stem of glass : these being electrified so as to diverge 

 freely, were covered by a capacious receiver, made extremely dry, and somewhat warm 

 within ; the insulating glass stem also being varnished, was warmed with a stick of 

 burning charcoal. The leaves did not, under these circumstances, cease to diverge 

 when the receiver was exhausted of its air to the greatest extent which could be 

 effected by a moderately good air-pump of the common kind. Dr. Turner has been 

 so good as to repeat the experiment with a more perfect apparatus, and he finds the 

 divergence equally perfect when only -g-i^rth part of the air remains in the receiver. 



81. Experiments of this kind, demand the most perfect manipulation and the most 

 rigorous mode of investigation, without which we are extremely liable to be deceived 

 by appearances : thus, the slightest deposition of moisture on the insulations becomes 

 fatal to a delicate experiment in vacuo, as also the proximity of conducting bodies 

 (44.). Two bodies also will frequently seem to open by a sort of flotation, on admit- 

 ting air into the receiver, however carefully the operation be managed ; whilst, in the 

 electrization of bodies suspended from rods passing into receivers through brass 

 plates, the electricity is liable to dissipation from the causes above assigned (78.). 



82. Upon a careful review of these inquiries, it would seem, that the more imme- 

 diate cause of electrical phenomena may be traced to certain peculiar states or con-^ 

 ditions under which common matter may become placed in respect of an extremely 

 subtile and universally pervading agency ; from which results an attractive force, 

 and, in the absence of an equivalent resistance, electrical currents. When these 

 states, which, for distinction sake, we may term electrical, are incomplete, they are 

 made perfect by the process termed induction ; in which case the attractive effect im- 

 mediately ensues : when they already exist, they become still further increased by the 

 same process, and a similar result happens. When the tendency to produce these 



* Singer's Electricity, p. 24. f Hauy's Philosophy. 



