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



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 contact 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 argu- 

 ment in favour of it. 



1280. I endeavoured to find some liquids which would in- 

 sulate well, and could be obtained in sufficient quantity for 

 these experiments. Oil of turpentine, native naphtha rectified, 

 and the condensed oil gas fluid, appeared by common ex- 

 periments to promise best as to insulation. Being left in con- 

 tact with fused carbonate of potassa, chloride of lime, and 

 quick lime for some days and then filtered, they were found 

 much injured in insulating power; but after distillation ac- 

 quired 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 contact would divide up to equal 

 tension between the two apparatus, yet without sensible loas 

 from the conducting power of app. i. ; and app. ii. were left 

 charged to a degree of tension above half the original charge, 

 it would indicate that oil of turpentine had less specific in- 

 ductive capacity than air ; or, if left charged below that mean 

 state of tension, it would imply that the fluid had the greater 

 inductive capacity. In an experiment of this kind, app. ii. 

 gave as its charge 390° before division with app. i., and 175° 

 afterwards, which is less than the half of 390°. Again, being 

 at 17.5° before division, it was 79° after, which is also less 

 than half the divided charge. Being at 79", it was a third 

 time divided, and then fell to 36°, less than the half of 79°. 

 Such are the best results I could obtain ; they are not incon- 

 sistent with the belief that oil of turpentine has a greater spe- 

 cific capacity than air, but they do not prove the fact, since 

 the disappearance of more than half the charge may be due 

 to the conducting power merely of the fluid. 



