420 Mr. Faraday's Researches in Electricity. {Series XL) 



very warm, was introduced into the apparatus, also warmed, 

 and experiments made with it as in the former instances 

 (1257. &c.). The general results were the same as with 

 shell-lac, i. e. glass surpassed air in its power of favouring 

 induction through it. The two best results as respected 

 the state of the apparatus for retention of charge, &c., 

 gave, when the air apparatus was charged first 1*336, and 

 when the glass apparatus was charged first I'^S, as the spe- 

 cific inductive capacity for glass, both being without correc- 

 tion. The average of nine results, four with the glass ap- 

 paratus first charged, and five with the air apparatus first 

 charged, gave 1*38 as the power of the glass apparatus; 1*22 

 and 1*46 being the minimum and maximum numbers with all 

 the errors of experiment upon them. In all the experiments 

 the glass apparatus took up its inductive charge instantly, 

 and lost it as readily ; and during the short time of each ex- 

 periment, acquired the peculiar state in a small degree only, 

 so that the influence of this state, and also of conduction upon 

 the results, must have been small. 



1274. Allowing specific inductive capacity to be proved 

 and active in this case, and 1*38 as the expression for the 

 glass apparatus, then the specific inductive capacity of flint 

 glass will be above 1*76, not forgetting that this expression is 

 for a piece of glass of such thickness as to occupy not quite 

 two-thirds of the space through which the induction is sus- 

 tained (1273. 1253.). 



1275. Sulphur. — The same hemisphere of this substance 

 was used in app. ii. as was formerly referred to (1242.). The 

 experiments were well made, i. e. the sulphur itself was free 

 from charge both before and after each experiment, and no 

 action from the stem appeared (1203. 1232.), so that no cor- 

 rection was required on that score. The following are the 

 results when the air apparatus was first charged and divided : 



App. i. Air. App. ii. Sulphur. 



Balls 280° 

 0° . . . 



.... 0° 

 438 .... 

 434 ... . 

 Charge divided. 

 .... 162 

 164 .... 



.... 160 

 162 ... . 



, . . . after discharge. 

 .... after discharge. 



