SPECIFIC INDUCTIVE CAPACITY OF SULPHUR — SPERMACETI. 33 



case the specific inductive capacity of sulphur itself as compared to air = 1 (12/0.) 

 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 perfectly clear, pellucid, and free from particles of 

 dirt (1267.)j 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 circumstances, 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 alto- 

 gether 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. 



1278. Having thus established the point in the most favourable cases that I could 

 anticipate, I proceeded to examine other bodies amongst solids, liquids, and gases. 

 These results I shall give with all convenient brevity. 



1279. Spermaceti. — A good hemisphere of spermaceti being tried as to conducting 

 power whilst its two surfaces were still in contact with the tin foil moulds used in 

 forming it, was found to conduct sensibly even whilst warm. On removing it from 

 the moulds and using it in one of the apparatus, it gave results indicating a specific 

 inductive capacity between 1*3 and 1*6 for the apparatus containing it. But as the 

 only mode of operation was to charge the air apparatus, and then after a quick con- 

 tact with the spermaceti apparatus, ascertain what was left in the former (1281.), 

 no great confidence can be placed in the results. They are not in opposition to the 

 general conclusion, but cannot be brought forward as argument in favour of it. 



1280. I endeavoured to find some liquids which would insulate well, and could be 

 obtained in suflftcient quantity for these experiments. Oil of turpentine, native 

 naphtha rectified, and the condensed oil gas fluid, appeared by common experiments 

 to promise best as to insulation. Being left in contact with fused carbonate of po- 

 tassa, chloride of lime, and quick lime for some days and then filtered, they were 

 found much injured in insulating power ; but after distillation acquired their best 

 state, though even then they proved to be conductors when large metallic contact 

 was made with them. 



1281. Oil of turpentine rectified. — I filled the lower half of app. i. with the fluid ; 

 and as it would not hold a charge sufficiently to enable me first to measure and then 

 divide it, I charged app. ii. containing air, and dividing its charge with app. i. by a 

 quick contact, measured that remaining in app. ii. : for, theoretically, if a quick con- 

 tact would divide up to equal tension between the two apparatus, yet without sen- 



MDCCCXXXVin. F 



