4kf 

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



SO as to keep it in a constantly uninsulated state. This was a very convenient form 

 of apparatus, and the results with it were the same as those described. 



1223. In another case the ball B was supported by a shell-lac stem, independently 

 of the excited cylinder of shell-lac, and at half an inch distance from it ; but the 

 effects were the same. Then the brass ball of a charged Leyden jar was used in 

 place of the excited shell-lac to produce induction ; but this caused no alteration of 

 the phenomena. Both positive and negative inducing charges were tried with the 

 same general results. Finally, the arrangement was inverted in the air for the pur- 

 pose of removing every possible objection to the conclusions, but they came out ex- 

 actly the same. 



1224. Some results obtained with a brass hemisphere instead of the ball B were 

 exceedingly interesting. It was 1*36 of an inch in diameter, (fig. 7-)? ^^^ being 

 placed on the top of the excited shell-lac cylinder, the carrier ball was applied, as 

 in the former experiments (1218.), at the respective positions delineated in the 

 figure. At i the force was 112°, at k 108°, at / 65°, at m 35°; the inductive force 

 gradually diminishing, as might have been expected, to this point. But on raising the 

 carrier to the position n the charge increased to 87° ; and on raising it still higher to a, 

 the charge still further increased to 105°: at a higher point still, j9, the charge taken 

 was smaller in amount, being 98°, and continued to diminish for more elevated posi- 

 tions. Here the induction fairly turned a corner. Nothing, in fact, can better show 

 both the curved lines or courses of the inductive action, disturbed as they are from 

 their rectilineal form by the shape, position, and condition of the metallic hemisphere ; 

 and also a lateral tension, so to speak, of these lines on one another : — all depending, 

 as I conceive, on induction being an action of the contiguous particles of the dielectric 

 thrown into a state of polarity and tension, and mutually related by their forces in all 

 directions. 



1225. As another proof that the whole of these actions were inductive I may state 

 a result which was exactly what might be expected, namely, that if uninsulated con- 

 ducting matter was brought round and near to the excited shell-lac stem, then the 

 inductive force was directed towards it, and could not be found on the top of the 

 hemisphere. Removing this matter the lines of force resumed their former direction. 

 The experiment affords proofs of the lateral tension of these lines, and supplies a 

 warning to remove such matter in repeating the above investigation. 



1226. After these results on curved inductive action in air I extended the experi- 

 ments to other gases, using first carbonic acid and then hydrogen : the phenomena 

 were precisely those already described. In these experiments I found that if the gases 

 were confined in vessels they required to be very large, for whether of glass or earthen- 

 ware, the conducting power of such materials is so great that the induction of the 

 excited shell-lac cylinder towards them is as much as if they were metal ; and 

 if the vessels be small, so great a portion of the inductive force is determined 



