364? Mr. Faraday's Researches in Electricity. (Series XI.) 



sustained for fifteen or twenty minutes at about 500°, the re- 

 turn charge was equal to 95° or 100°, and was about fourteen 

 minutes arriving at the maximum effect. A charge continued 

 for not more than two or three seconds was here succeeded by 

 a return charge of 50° or 60°. The observations formerly 

 made (1234.) held good with this substance. Spermaceti, 

 though it will insulate a low charge for some time, is a better 

 conductor than shell-lac, glass, and sulphur; and this con- 

 ducting power is connected with its readiness in exhibiting 

 the particular effect under consideration. 



1241. Sulphur. — I was anxious to obtain the amount of 

 effect with this substance, first, because it is an excellent in- 

 sulator, and in that respect would illustrate the relation of the 

 effect to the degree of conducting power possessed by the di- 

 electric (1247.); and in the next place, that 1 might obtain 

 that body giving the smallest degi'ee of the effect now under 

 consideration, for the investigation of the question of specific 

 inductive capacity (1277.). 



1242. With a good hemispherical cup of sulphur cast solid 

 and sound, I obtained the return charge, but only to an 

 amount of 17° or 18°. Thus glass and sulphur, which are 

 bodily very bad conductors of electricity, and indeed almost 

 perfect insulators, gave very little of this return charge. 



1243. I tried the same experiment having air only in the 

 inductive apparatus. After a continued high charge for some 

 time I could obtain a little effect of return action, but it was 

 ultimately traced to the shell-lac of the stem. 



1244. I sought to produce something like this state with one 

 electric power and without induction ; for upon the theory 

 of an electric fluid or fluids, that did not seem impossible, 

 and then I should have obtained an absolute charge (1169. 

 1177.), or something equivalent to it. In this I could not 

 succeed. 1 excited the outside of a cylinder of shell-lac very 

 highly for some time, and then quickly discharging it (1203.), 

 waited and watched whether any return charge would appear, 

 but such was not the case. This is another fact in favour of 

 the inseparability of the two electric forces, and another argu- 

 ment for the view that induction and its concomitant phaeno- 

 mena depend upon a polarity of the particles of matter. 



1245. Although inclined at first to refer these effects to a 

 peculiar masked condition of a certain portion of the forces, 

 I think I have since correctly traced them to known prin- 

 ciples of electrical action. The effects ap})ear to be due to 

 an actual penetration of the charge to some distance within 

 the electric, at each of its two surfaces, by what we call con- 

 duction; so that, to use the ordinary phrase, the electric 



