ELECTRICITY. 



Graphite at 22* C. (I.) (Matthiessen) 0'0023& 



(If.) 00378 



(111.) ,, 0-0418 



Bunsen's battery coke at 26 C. ,, 0672 



Gas coke at 25' C. ,, 0'00428 



Gas coke at O 3 C. (Siemens) 00702 



N.B. The resistance of the different varieties of carbon varies 

 very much, it decreases about -^V^r for every 1 C. through which 

 the sample is heated between C. and 100 C. It also decreases as 

 the pressure increases. 



(83) SPECIFIC RESISTANCE OF INSULATORS IN B.A. UNITS X lo' ! 

 (MEGOHMS NEARLY). 



Ice at - 12-4 C. (Ayrton and Perry) 2240 



- -2C. ,, ., ' 284 



Glass (soda-lime A2'54) at 20 C. (Foussereau) 9'1 X 10 7 



at 61-2 C. 



Glass (crystal A 2 '94) below 40 C. , , 



at46C. 



, at 105 C. 



Glass (Bohemian), resistance 10 to 15 times that of 

 common glass at the same temperature 



(Fousserau) 



Glass (white French) at 200 C. (Beetz) 104'3 



6-182 X 10 !) 

 1-16 X 10? 



at 350 C. 

 (green bottle) at 200 C. 



at 350 9 C. 

 (heavy lead) at 200 C, 



at 350 C. 



(from J. Clerk Maxwell) 



Glass at 200 C. 

 at 250 C. 

 at 300 C. 

 ,, at 400 C. . 



Mica at 20 C. (Ayrton and Perry) 

 Shellac at 28 C. ,, 



Paraffin at 46 C. 

 Ebonite at 46 C. 



Gutta Percha at C 



at 24 C. (J. C. Maxwell) 



(Latimer Clark) 4'5 X 10 8 



,, minimum (F. Jenkin) 2'5 X 10 7 



,, maximum ,, 5 X 10 8 



,, covering of 2nd Atlantic cable 3'42 X 10- 



Hooper's composition at C 3'2 X 10 10 



at24C. (1.) 1-5 X 10 10 



(II.)(Persian Gulf cable) 7 '5 X 10 9 



0-33 

 31-1 



0-128 

 323-8 



0-84G 

 22-7 

 1-39 

 0-148 

 0-0735 

 8-4 X 10 7 

 9 X 109 

 3-4 X 10- 

 2 8 X 1C 10 

 7 X 10 y 

 3-53 X 10 8 



