Allen — The Insulating Properties of Erinoid. 



339 



agreement of results was always found. Thus the results of the leakage test 

 on a sample of black erinoid at 16°C. were found to be 



Exactly the same set of values were obtained when the direction of the 

 charging voltage was reversed. 



The leakage of the arrangement itself, that is the condenser and voltmeter, 

 was 0-4 volt in 120 seconds. 



From these results 



120 



B 



2 - 3 x 2 log, 



113 megohms. 



57-4 



The test was then made by the galvanometer method, using a direct 

 voltage of 134, and the value obtained for R was 110 megohms. In this 

 experiment the deflection of the galvanometer remained steady for several 

 minutes' observation, and was of the same value when the direction of the 

 applied voltage was reversed. 



The agreement between the galvanometer and the megger results was 

 also very close when testing the sample at higher temperatures. 



Voltage test of erinoid and fibre. 



Tests were made on a number of samples of erinoid, and also on one of 

 fibre, to determine whether the insulation resistance depended upon the value 

 of the applied voltage or not. 



Three similar tubes of white erinoid of different thicknesses were tested, 

 and the results obtained are given in Tables 3 and 4, in which E is the voltage 

 applied to the sample, and D the deflection of the galvanometer, which was 

 shunted in the case of the sample tested at 41°C. 



SCIEN. PROC. E.D.S., VOL XV., NO. XXIX, 



3 J 



