Allen — The Insulating Properties of Erinoid. 



351 



The internal diameter in this case was l - 3 cms., and the external diameter 

 2 - 6 cms. For the following cases the internal diameter was l - 55 cms., and 

 the effective length of the sample tube in every case 4;6 cms. 



Table 13. 



White erinoid; thickness, - 32 cm. 

 <r = 80 E. 



This sample was heated up to 110° C. and the values of the three highest 

 temperatures of the table were obtained. It was then allowed to cool, and 

 the next day values were taken for the ascending temperatures up to 65'5° C. 

 given in the table. 



In the previous heating the sample was exposed to a temperature of 100 

 to 110° C. for about one hour, and at the end of the test of the second day 

 was observed to be very slightly discoloured, due to a little burning of the 

 material. 



The insulation resistance as judged by the results of the other samples of 

 white erinoid was practically unaltered by exposure to this high temperature. 



