6 DR. FARADAY'S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XI.) 



position of the existence of an electric fluid or fluids. It may be impossible to have 

 the one fluid or state in a free condition without its producing by induction the 

 other, and yet possible to have cases in which an isolated portion of matter in one 

 condition being uncharged, shall, by a change of state, evolve one electricity or the 

 other : and though such evolved electricity might immediately induce the opposite 

 state in its neighbourhood, yet the mere evolution of one electricity without the other 

 in the Jirst instance, would be a very important fact in the theory which assumes a 

 fluid or fluids : these theories as I understand them assigning not the slightest reason 

 why such an effect should not occur. 



11 76. But on searching for such cases I cannot find one. Evolution by friction, as 

 is well known, gives both powers in equal proportion. So does evolution by che- 

 mical action, notwithstanding the great diversity of bodies which may be employed, 

 and the enormous quantity of electricity which can in this manner be evolved (37 1 . 

 376. 861. 868.) The more promising cases of change of state, whether by evapora- 

 tion, fusion, or the reverse processes, still give both forms of the power in equal pro- 

 portion ; and the cases of splitting of mica and other crystals, the breaking of sulphur, 

 &c. &c., are subject to the same limitation. 



1177. As far as experiment has proceeded, it appears, therefore, impossible either 

 to evolve or make disappear one electric force without equal and corresponding 

 change in the other. It is also equally impossible experimentally to charge a por- 

 tion of matter with one electric force independently of the other. Charge always im- 

 plies induction, for it can in no instance be effected without ; and also the presence 

 of the two forms of power, equally at the moment of development and afterwards. 

 There is no absolute charge of matter with one fluid ; no latency of a single electricity. 

 This though a negative result is an exceedingly important one, being probably the 

 consequence of a natural impossibility, which will become clear to us when we un- 

 derstand the true condition and theoiy of the electric power. 



1178. The preceding considerations already point to the following conclusions: 

 bodies cannot be charged absolutely, but only relatively, and by a principle which is 

 the same with that of induction. All charge is sustained by induction. All pheno- 

 mena of intensity include the principle of induction. All excitation is dependent on 

 or directly related to induction. All currents involve previous intensity and there- 

 fore previous induction. Induction appears to be the essential function both in the 

 first development and the consequent phenomena of electricity. 



^ iii. Electrometer and inductive apparatus employed. 



1 179- Leaving for a time the further consideration of the preceding facts until they 

 can be collated with other results bearing directly on the great question of the na- 

 ture of induction, I will now describe the apparatus I have had occasion to use ; and 

 in proportion to the importance of the principles sought to be established is the ne- 

 cessity of doing this so clearly, as to leave no doubt of the results behind. 



