No absolute Charge of Matter, — All Inductive. 287 



other, and yet possible to have cases in which an isolated por- 

 tion 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 oppo- 

 site state in its neighbourhood, yet the mere evolution of one 

 electricity without the other in the Jlrst 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. 



1 176. 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 chemical action, not- 

 withstanding the great diversity of bodies which may be em- 

 ployed, and ihe enormous quantity of electricity which can in 

 this manner be evolved (371. 376. 861. 868,). The more 

 promising cases of change of state, whether by evaporation, 

 fusion, or the reverse processes, still give both forms of the 

 power in equal proportion ; and the cases of splitting of mica 

 and other crystals, the breaking of sulphur, &c. &c., are sub- 

 ject to the same limitation. 



1 1 77. As far as experiment has proceeded, it appears, there- 

 fore, impossible either to evolve or make disappear one elec- 

 tric force without equal and corresponding change in the 

 other. It is also equally impossible experimentally to charge 

 a portion of matter with one electric force independently of 

 the other. Charge always implies 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 nega- 

 tive result is an exceedingly important one, being probably 

 the consequence of a natural impossibility, which will become 

 clear to us when we understand the true condition and theory 

 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 

 thatof induction. AWchargeis sustained by induction. All phae- 

 nomena of intensity include the principle of induction. All 

 excitation is dependent on or directly related to induction. All 

 currents involve previous intensity and therefore previous in- 

 duction. Induction appears to be the essential function both 

 in the first development and the consequent ph;enomena of 

 electricity. 



