Specific Inductive Capacity of Shell-lac. 4* 17 



1264<. The shell-lac was then removed from app. i. and put 

 into app. ii. and the experiments of division again made. I 

 give the results, because I think the importance of the point 

 justifies and even requires them. 



App. i. Air. App. ii. Ijac. 



Balls 200°. 



° . . . . 0° 

 286 .... 

 283 .... 



Charge divided. 

 .... 110 

 109 ... . 



. . . . 0*25 after discharge. 

 Trace .... after discharge. 



Here app. i. retained 109°, having lost 174° in communi- 

 cating 110° to app. ii. ; and the capacity of the air app. is to 

 the lac app., therefore, as 1 to 1 '58. If the divided charge 

 be corrected for an assumed loss of only 3°, being the amount 

 of previous loss in the same time, it will make the capacity 

 of the shell-lac app. 1*55 only. 



1 265. Then app. ii. was charged, and the charge divided 

 thus: 



App. i. Air. App. ii. Lac. 

 0° . . , . 



.... 256° 



.... 251 



Charge divided. 

 \\Q . . . . 



.... 149 

 a little .... after discharge. 



. . . . a little after discharge. 



Here app. i. acquired a charge of 146°, while app. ii. lost 

 only 102° in communicating that amount of force; the capa- 

 cities being, therefore, to each other as 1 to 1*43. If the 

 whole transferable charge be corrected for a loss of 4° pre- 

 vious to division, it gives the expression of 1*49 for the capa- 

 city of the shell-lac apparatus. 



1266. These four expressions of 1*47, 1*50, \'55i and 1*49 

 for the power of the shell-lac apparatus, through the different 

 variations of the experiment, are very near to each other ; the 

 average is close upon 1 '5, which may hereafter be used as the 

 expression of the result. It is a very important result; and, 

 showing for this particular piece of shell-lac a decided supe- 

 riority over air in allowing or causing the act of induction, it 



Phil. Mafr. S. 3. Vol. 13. No. 84. Dec. 1838. 2 E 



