Specific Inductive Capacity of Sulphur and Spermaceti. 421 



Here app. i. retained 164°, having lost 270° in communi- 

 cating 162° to app. ii.j and the capacity of the air apparatus 

 is to that of the sulphur apparatus as I to 1 '66. 



1276. Then the sulphur apparatus was charged first, thus: 



App. i. App. ii. 



.... 0° 

 0° . . . . 



.... 395 



.... 388 

 Charge divided. 

 237 ... . 



.... 238 

 . . . . after discharge. 



. . . . after discharge. 



Here app. ii. retained 238°, and gave up 150° in communi- 

 cating a charge of 237° to app. i., and the capacity of the air 

 apparatus is to that of the sulphur apparatus as 1 to 1'58. 

 These results are very near to each other, and we may take the 

 mean 1*62 as representing the specific inductive capacity of 

 the sulphur apparatus; in which case the specific inductive 

 capacity of sulphur itself as compared to air = 1 (1270.) will 

 be about or above 2'24. 



1277. This result with sulphur I consider as one of the 

 most unexceptionable. The substance when fused was per- 

 fectly clear, pellucid, and free from particles of dirt (1267.), 

 so that no interference of small conducting particles confused 

 the result. The body when solid is an excellent insulator, 

 and by experiment was found to take up, with great slowness, 

 that state (1241. 1242.) which alone seemed likely to disturb 

 the conclusion. The experiments themselves, also, were free 

 from any need of correction. Yet notwithstanding these cir- 

 cumstances, so favourable to the exclusion of error, the result 

 is a higher specific inductive capacity for sulphur than for any 

 other body as yet tried; and though this may in part be due 

 to the sulphur being in a better shape, i. e. filling up more 

 completely the space o^o^ (fig. 1.) than the cups of shell-lac 

 and glass, still I feel satisfied that the experiments altogether 

 fully prove the existence of a difference between dielectrics as 

 to their power of favouring an inductive action through them ; 

 which difference may, for the present, be expressed by the 

 term specific inductive capacity. 



1 278. Having thus established the point in the most favour- 

 able cases that I could anticipate, I proceeded to examine 

 other bodies amongst solids, liquids, and gases. These re- 

 sults I shall give with all convenient brevity. 



1279. Spermaceti. — A good hemisphere of spermaceti being 



