Allen — The Insulating Properties of Erinoid. 



341 



Table 5. 



Red fibre. Sheet form. Thickness, 1 cm. 

 Temp. 16° C. 



Immediately after these values were taken , a test was made to ascertain 

 whether any dielectric absorption was present. This was done by passing the 

 current through the sample in the same direction as in the preceding test 

 namely from the mercury on which the sheet floated, through its thickness, 

 to the mercury on the top surface of the sheet walled round by paraffin wax, 

 and applying a voltage of 590 to the sample for three minutes while noting 

 the deflection D. The latter was found to remain steady at 330. 



This voltage was then suddenly reversed and 1) was found to start at 358 

 then gradually rise to 368 after two minutes and 370 after three minutes 

 Eeversing again the following values were obtained : — 



t being the time in minutes. 



Eeversing, the value of D only changed from 368 to 365 in three minutes. 

 The next reversal gave : — 



and at a final reversal D only fell from 370 to 367 in four minutes. 



Throughout this test the temperature remained steady at 16°C. and the 

 applied voltage at 590. 



3i2 



