234 



Profs. W. E. Ayrton and John Perry. [Mar. 21, 



ordinates of the points E, a, b, c, &c. . . . F, have the values given in the 

 following table : — 





Temperature. 



1 i Ei 



- loff - 

 £ Eo 



X 



in meg-ohms. 





49° 7 0. 



-0044 



8857 xlO 6 





51° *2 



-0050 



7794< xlO 6 



E 



52° *6 



"0122 



3195 x 1 6 



a 



Ore \J 



-0677 



57^ 7 x 1 c 6 



b 



54° ;65 



1620 



240 -6 x 10 6 



c 



55° -2 



3612 



107-9 xlO 6 



d 



57° -0 



1 7040 



22-88 xlO 6 



F 



58° -0 



3 -2776 



11 -90 x 10 6 





59° 



4 -1608 



9 -367 x 10 6 



Of the curve GCD, the part from G to C was obtained without 

 using the condenser, and for the part from C to D, the condenser was 

 employed. The co-ordinates of the points C, a, b, &c, . . . D are as 

 follows : — 





Temperature. 



t ° E 2 



in 



X 



megohms. 



c 



59° -8 C. 



-0065 



8 



•104 X 10 6 



a 



61° 5 



-0096 



5 



•487 x 10 6 



b 



62° -85 



-0097 



5 



•430 x 10* 



c 



64° -4 



-0126 



4 



•180 x10 s 



d 



66° -45 



-0138 



3 



•187 xlO 6 



e 



68° -5 



-0193 



2 



729 xlO 6 



f 



70° -2 



-0250 



2 



•107 x 10 6 



g 



72° -2 



-0267 



1 



•972 x 10 6 



h 



73° -8 



-0285 



1 



•848 x 10 6 



D 



75° -2 



0-0293 



1 



798 xlO 6 



Assuming that the paraffin is always in the same state when the 

 thermometer gives the same reading during a regular rise in tempera- 

 ture of the apparatus, we find, 



1 E 



_ log — without condenser for 59° C. to be 4 "36. 

 t & E, 



1 E 



_ log — - with condenser for 59° C. to be "0059. 

 t E 2 



Therefore the ratio of the relative conductivities measured without 

 and with the condenser, is about 740, and hence, assuming the specific 

 inductive capacity of paraffin does not change much with temperature, 

 and that the change of capacity of the pair of quadrants can be 

 neglected, we can calculate the specific resistance in megohms of a 

 cubic centimetre of paraffin wax from our time readings by the 



