336 



Scientific Proceedings, Royal Dublin Society. 



a few minutes, and its resistance measured as before for the same set of 

 temperatures. The values obtained were as follows : — 



By graphing the values of resistance after immersion against temperature 

 an approximate straight line is obtained. This suggests that the absorbed 

 water is distributed more or less uniformly throughout the material as the 

 graph of the resistance before immersion, against the temperature, is not a 

 straight line. 



The change of resistance due to the immersion of erinoid in different 

 liquids for two weeks was found at the National Physical Laboratory to be 

 as follows : — 



Specific insulation resistance of erinoid and fibre at ordinary temperatures. 



The insulation resistance of erinoid and fibre at ordinary temperatures 

 was found for samples in the form of tubes and plates. The tubes were 

 turned in a lathe, but the surfaces of the plates were unprepared in any way. 

 The latter were fitted on one face with a bounding ridge of paraffin wax 

 3 or 4 cms. in width by 1 or 2 cms. in depth. The other face was placed in 

 contact with mercury in a dish, and the receptacle on the upper face was 

 partly filled with mercury. 



In some cases the mercury at the top and bottom of the plate was 

 replaced by water so as to test whether better contact was made between the 

 material and its water electrodes than in the case of mercury. 



A test was made on both fibre and erinoid to determine whether the 

 surface leakage between the electrodes of the sample had an appreciable 

 effect on the resistance being measured, and it was found that this effect was 

 negligible. 



